▼ SummaryObjective

Resistin is a secreted factor that is elevated in rheumatoid arthritis (RA) and believed to drive joint inflammation in vivo. This study was undertaken to determine if resistin is present in the joint following joint injury and to elucidate the role of resistin in cartilage degradation.

Methods

The level of resistin was measured in paired synovial fluid (SF) and serum samples from patients following joint injury (anterior cruciate ligament, ACL or meniscus tear). Localization of resistin was visualized by immunohistochemistry of synovial tissue and cartilage from healthy and OA donors. Mouse and human cartilage cultures were used to assess the effect of resistin on cartilage metabolism.

Results

In trauma patients, resistin levels declined with increasing time post injury. The resistin levels were highest in samples collected up to 1 week following traumatic injury (SF: 2980pg/ml, serum: 7901pg/ml) and lowest in samples collected 6–26 years post injury (SF: 686pg/ml, serum: 5682pg/ml). Resistin was shown to be expressed in macrophage-like cells in both healthy and OA synovial tissue. Treatment of mouse cartilage cultures with recombinant resistin led to a dose dependent loss of proteoglycan and induction of inflammatory cytokine and PGE₂ production. Recombinant resistin inhibited proteoglycan synthesis in human cartilage explants.

Conclusion

Resistin is elevated both systemically and locally in the weeks immediately following joint injury and has a direct effect on cartilage matrix turnover and cytokine production. Resistin may play a role in the early stages of trauma-induced OA and may represent a new therapeutic target to slow joint destruction in OA.

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Mechanical loads placed on connective tissues alter gene expression in fibroblasts through mechanotransduction mechanisms by which cells convert mechanical signals into cellular biological events, such as gene expression of extracellular matrix components (e.g., collagen). This mechanical regulation of ECM gene expression affords maintenance of connective tissue homeostasis. However, mechanical loads can also interfere with homeostatic cellular gene expression and consequently cause the pathogenesis of connective tissue diseases such as tendinopathy and osteoarthritis. Therefore, the regulation of gene expression by mechanical loads is closely related to connective tissue physiology and pathology. This article reviews the effects of various mechanical loading conditions on gene regulation in fibroblasts and discusses several mechanotransduction mechanisms. Future research directions in mechanoregulation of gene expression are also suggested.

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The majority of studies on cranial cruciate ligament (CrCL) disease to date have been carried out on dogs that already sustained a CrCL rupture, which is the end-stage of the disease. Investigations have recently been carried out to study humoral and cellular immunopathological mechanisms in predisposed dogs before clinical rupture of the contralateral CrCL. The cruciate ligaments are mainly composed of collagen type I, and immune responses to collagen have been suggested as a cause of CrCL degradation in dogs. None of these investigations showed evidence that anticollagen type I antibodies alone initiate CrCL damage. However, in predisposed dogs a distinct anticollagen type I antibody gradient was found towards the contralateral stifle joint that eventually sustained a CrCL rupture, suggesting that there was an inflammatory process present in these joints before detectable joint instability occurred. The importance of cellular reactivity to collagen type I in cruciate disease also remains unclear. Peripheral blood mononuclear cell proliferation to collagen type I was very diverse in dogs with cruciate disease whereas some sham operated dogs and healthy dogs tested positive as well. It is not yet determined whether cellular reactivity to collagen type I exists locally in the stifle joints nor whether this could initiate CrCL degradation.

Inflammatory processes within the stifle joint can alter the composition of the cruciate ligaments. In animal models of immune-mediated synovitis, the mechanical strength of the CrCL is significantly reduced. Immunohistochemical studies on synovial tissues from dogs with rheumatoid arthritis and dogs with cruciate disease revealed that the pathologic features are similar in both joint pathologies and that the differences are mainly quantitative. Joint inflammation induced by biochemical factors such as cytokines has been implied in CrCL degeneration. In several studies, the levels of pro-inflammatory and T helper cytokines were measured in dogs that sustained a CrCL rupture, but the exact role of the various cytokines in the pathogenesis of CrCL disease remains inconclusive. More recently, the levels of the cytokines have been investigated over time in predisposed dogs before and after CrCL rupture. IL-8 expression tended to be higher in stifle joints that will rupture their CrCL during the next 6 months than in those that will not, indicating an inflammatory process in these joints before clinical rupture.

This review provides a comprehensive overview of all possible implications of humoral and cell-mediated immune responses published in dogs with cruciate disease together with publications from human joint diseases. Furthermore, this review highlights recent findings on cytokines and proteinases in the accompanying joint inflammation.

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Muscle atrophy commonly follows anterior cruciate ligament (ACL) injury and surgery. Proinflammatory cytokines can induce and exacerbate oxidative stress, potentiating muscle atrophy. The purpose of this study was to evaluate the influence of prior antioxidant (AO) supplementation on circulating cytokines following ACL surgery. A randomized, double-blind, placebo-controlled trial was conducted in men undergoing ACL surgery, who were randomly assigned to either: (1) AO (200 IU of vitamin E (50% d-alpha-tocopheryl acetate and 50% d-α-tocopherol) and 500 mg ascorbic acid), or (2) matching placebos (PL). Subjects took supplements twice daily for 2 weeks prior to and up to 12 weeks after surgery. Each subject provided five blood samples: (1) baseline (Bsl, prior to supplementation and ∼2 weeks prior to surgery), (2) presurgery (Pre), (3) 90 min, (4) 72 h, and (5) 7 days postsurgery. Following surgery, inflammation and muscle damage increased in both groups, as assessed by increased circulating IL-6, C-reactive protein, and creatine kinase. During AO supplementation, plasma α-T and AA increased while γ-T concentrations decreased significantly (P< 0.05). At 90 min the AO group displayed a significant decrease in AA, an inverse correlation between AA and (interleukin) IL-8 (r²= 0.50, P< 0.05), and a significantly lower IL-10 response than that of the PL group. IL-10 was significantly elevated at 90 min and 72 h in the PL group. In summary, our findings show that circulating inflammatory cytokines increase and AO supplementation attenuated the increase in IL-10 in patients post-ACL surgery.

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Muscle atrophy commonly follows anterior cruciate ligament (ACL) injury and surgery. Proinflammatory cytokines can induce and exacerbate oxidative stress, potentiating muscle atrophy. The purpose of this study was to evaluate the influence of prior antioxidant (AO) supplementation on circulating cytokines following ACL surgery. A randomized, double-blind, placebo-controlled trial was conducted in men undergoing ACL surgery, who were randomly assigned to either: (1) AO (200 IU of vitamin E (50% d-alpha-tocopheryl acetate and 50% d-α-tocopherol) and 500 mg ascorbic acid), or (2) matching placebos (PL). Subjects took supplements twice daily for 2 weeks prior to and up to 12 weeks after surgery. Each subject provided five blood samples: (1) baseline (Bsl, prior to supplementation and ∼2 weeks prior to surgery), (2) presurgery (Pre), (3) 90 min, (4) 72 h, and (5) 7 days postsurgery. Following surgery, inflammation and muscle damage increased in both groups, as assessed by increased circulating IL-6, C-reactive protein, and creatine kinase. During AO supplementation, plasma α-T and AA increased while γ-T concentrations decreased significantly (P< 0.05). At 90 min the AO group displayed a significant decrease in AA, an inverse correlation between AA and (interleukin) IL-8 (r²= 0.50, P< 0.05), and a significantly lower IL-10 response than that of the PL group. IL-10 was significantly elevated at 90 min and 72 h in the PL group. In summary, our findings show that circulating inflammatory cytokines increase and AO supplementation attenuated the increase in IL-10 in patients post-ACL surgery.

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Objective: In this longitudinal MR study the early stages of joint pathology in two surgically-induced rabbit models of osteoarthritis (OA) were monitored by in vivo contrast-enhanced MRI at 7.1T. Qualitative and quantitative MR data were compared with macroscopic and microscopic findings.

Method: Scanning of mature, male New Zealand White rabbits (N=12) was performed before surgery, and at 2, 4, and 8 weeks after unilateral transection of the anterior cruciate ligament (ACLT), medial meniscectomy (ME), or sham operation. MR-images were simultaneously obtained of both knee joints after intravenous injection of Magnevist™. We implemented a 2D T1-weighted (T1w) coronal, fat-saturated gradientecho protocol (68×138μm², slice thickness 1mm). Additionally, consecutive 3D gradientecho images were obtained from two sham-operated and two rabbits of the ME group (234×273×234μm³). ACLT animals were sacrificed at 2 weeks (N=1), and 8 weeks (N=3), ME animals were sacrificed at 4 weeks (N=2), and 8 weeks (N=4), and sham-operated animals were sacrificed at 2 weeks (N=1) and 8 weeks (N=1), respectively.

Results: Both OA models reflected important characteristics of the clinical picture of OA. With MR we were able to monitor time dependently the decline of synovial effusion and the formation of osteophytes. Morphologic MR examination showed a moderate to high accuracy for detecting synovial effusion (75%), meniscus (86%) and cruciate ligament (91%) lesions, and osteophytes (88%) as assessed by macroscopic examination. False-negative MR findings for gross macroscopic changes were due to the relative high slice thickness in 2D scans and the fact that the slices only covered the main weightbearing area of the femorotibial joint. Contour abnormalities of articular cartilage were not reliably detected. Quantitative analysis revealed a statistically significant increase of cartilage signal intensity in medial tibial cartilage (48±9% ACLT, and 29±9% ME in 2D datasets) as compared to contralateral control knees in two-week scans. Signal enhancement persisted or increased at later dates.

Conclusion: With high-resolution contrast-enhanced MRI at 7.1T the time course of gross pathologic changes in rabbit knees with surgically induced OA can be monitored. Still insufficient spatial resolution and image contrast of the applied 2D protocols limit the sensitivity and prohibit detection of articular cartilage contour abnormalities. However, signal alterations in the cartilage layer indicate alterations of tissue composition at a very early stage of OA development.When used with 3D protocols, contrast-enhanced MRI offers a promising tool for qualitative and quantitative in vivo monitoring of OA in rabbit models.

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Bryant AL, Creaby MW, Newton RU, Steele JR. Dynamic restraint capacity of the hamstring muscles has important functional implications after anterior cruciate ligament injury and anterior cruciate ligament reconstruction.

Objective

The purpose of this study was to investigate the relation between knee functionality of anterior cruciate ligament deficient (ACLD) and anterior cruciate ligament reconstruction (ACLR) patients and hamstring antagonist torque generated during resisted knee extension.

Design

Cross-sectional.

Setting

Laboratory based.

Participants

Male ACLD subjects (n=10) (18–35y) and 27 matched males who had undergone ACLR (14 patella tendon [PT] grafts and 13 combined semitendinosus/gracilis tendon grafts).

Interventions

Not applicable.

Main Outcome Measures

Knee functionality was rated (0- to 100-point scale) by using the Cincinnati Knee Rating System. Using electromyography data from the semitendinosus (ST) and biceps femoris muscles, we created a mathematical model to estimate the opposing torque generated by the hamstrings during isokinetic knee extension in 10° intervals from 80° to 10° knee flexion.

Results

Pearson product-moment correlations revealed that more functional ACLD subjects generated significantly (P<.05) higher hamstring antagonist torque throughout knee extension. In contrast, more functional PT subjects produced significantly lower hamstring antagonist torque at 80° to 70° knee flexion, whereas no significant associations were found between hamstring antagonist torque and knee functionality for the ST/gracilis tendon subjects.

Conclusions

An increased hamstring antagonist torque generated by the more functional ACLD subjects, reflective of increased hamstring contractile force, is thought to represent a protective mechanism to compensate for mechanical instability. The restoration of anterior knee stability through ACLR negates the need for augmented hamstring antagonist torque.

▼ Muscle atrophy and weakness are predominant impairments after anterior cruciate ligament (ACL) surgical repair. We tested the hypothesis that vitamin E and C supplementation will improve recovery from ACL injury. Men undergoing elective ACL surgery were randomly assigned to twice-daily supplements of either antioxidants (AO; vitamins E and C, n=10) or matching placebos (n=10) from 2 weeks before until 3 months after surgery. Each subject provided several fasting blood draws, two muscle biopsies from the thigh muscle of the injured limb, and strength and thigh circumference measurements of the lower limbs. Muscle atrophy was apparent in both groups before and several days after surgery. Compared with baseline measurements, peak isometric force of the injured limb increased significantly (P<0.05) by 3 months postsurgery in both treatment groups; however, AO supplementation did not augment these strength gains. By contrast, baseline plasma ascorbic acid concentrations correlated (r=0.59, P=0.006) with subsequent improvement in the strength of the injured limb. In summary, vitamin E and C supplementation was ineffective in potentiating the improvement in force production by the injured limb; however, baseline vitamin C status was associated with beneficial outcomes in strength, suggesting that long-term dietary habits are more effective than short-term supplements.

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Wagemakers HP, Luijsterburg PA, Boks SS, Heintjes EM, Berger MY, Verhaar JA, Koes BK, Bierma-Zeinstra SM. Diagnostic accuracy of history taking and physical examination for assessing anterior cruciate ligament lesions of the knee in primary care.

Objective

To assess the diagnostic accuracy of history taking and physical examination for assessing anterior cruciate ligament (ACL) lesions in primary care.

Design

Cross-sectional diagnostic study.

Setting

Primary care.

Participants

Patients (N=134; age, 18–65y) who consulted their general practitioner (GP) within 5 weeks after injury.

Interventions

Not applicable.

Main Outcome Measures

Index tests were obtained with a questionnaire and physical examination. Magnetic resonance imaging (MRI) was used as the reference test. Logistic regression analysis was used to determine associations with ACL lesions. Diagnostic accuracy was determined by calculating sensitivity (Se), specificity (Sp), predictive values, and likelihood ratio (LR).

Results

MRI showed an ACL lesion in 28 of 134 included patients. “Effusion,” “popping sensation,” “giving way,” and “anterior drawer test (ADT)” showed associations with an ACL lesion (P<.05). Popping sensation showed Se, Sp, positive predictive value (PPV), and positive LR (LR⁺) of .63, .73, .39, and 2.3, respectively. Combining determinants from history taking (2 of 3 positive results regarding effusion, popping sensation, and giving way) improved diagnostic accuracy (Se, .71; Sp, .71; PPV, .42; and LR⁺, 2.5). The ADT added diagnostic accuracy to these combinations (Se, .63; Sp, .85; PPV, .52; and LR⁺, 4.2).

Conclusions

ACL lesions are seen frequently. Based on history taking (effusion, popping sensation, and/or giving way) and physical examination (ADT), GPs can screen for ACL lesions in primary care.

▼  SummaryObjective

Degeneration in cruciate ligaments results from abnormal biomechanical stress and the aging process. Such degeneration is a common outcome in patients with osteoarthritis (OA) of the knee and contributes to the progression of OA. However, to date, there are no specific markers that can predict the extent of ligament degeneration. We hypothesized that the extent of degeneration has correlations to increased chondrogenic potential.

Methods

Twenty anterior cruciate ligaments (ACLs) and 30 posterior cruciate ligaments (PCLs) from 30 knees of 28 adult patients with OA at the time of total knee arthroplasty were used for the study. Degeneration was histologically assessed using a grading system. Expressions of Scleraxis (as a ligament cell marker) and Sry-type HMG box 9 (SOX9) (as a chondrogenic marker) were immunohistochemically assessed in each grade.

Results

We found the opposite expression pattern between Scleraxis and SOX9 according to the grade. The percentage of Scleraxis-positive cells decreased significantly by grade (60.9±23.7 in grade 1, 39.7±30.5 in grade 2, and 13.9±27.1 in grade 3, P<0.0001). In contrast, the percentage of SOX9-positive cells increased significantly by grade (2.5±4.9 in grade 1, 17.5±13.4 in grade 2, and 50.9±27.1 in grade 3, P<0.0001). Furthermore, co-localized expression of both Scleraxis and SOX9 was demonstrated in chondrocyte-like cells.

Conclusions

This study indicates that chondrogenic differentiation is associated with the progression of degeneration in human ligaments. Our results suggest that the expression of SOX9 as a chondrogenic marker could be an indicator for the extent of degeneration in human ligaments. It remains to be elucidated whether suppression of chondrogenic differentiation can prevent progression of the degenerative process of cruciate ligaments in patients with OA.

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This study was designed to investigate the effects of rhein, the active metabolite of diacerhein, on the metabolic functions of human chondrocytes cultured in alginate beads.

Enzymatically isolated osteoarthritic (OA) chondrocytes were cultured in alginate beads in a well-defined culture medium for 12 days. Rhein was tested in a range of concentrations comprised between 10⁻⁷ and 4×10⁻⁵M, in the presence or absence of 10⁻¹⁰M IL-1β. Interleukin (IL)-6 and -8, macrophage inflammatory protein (MIP-1β), stromelysin-1 (MMP-3), aggrecan (AGG), tissue inhibitor of metalloproteinases-1 (TIMP-1), prostaglandin E₂ (PGE₂) and nitric oxide (NO) productions were assayed. Cyclooxygenase-2 (COX-2) and inducible NO synthase (iNOS) mRNA steady-state levels were also quantified. In the basal condition, 10⁻⁵M rhein increased by 46.5% the production of AGG, decreased by 17–30% the production of IL-6, MMP-3, NO and MIP-1β but enhanced by 50% the production of PGE₂. IL-1β increased IL-6, IL-8, MIP-1β, NO, PGE₂ and MMP-3 productions, but inhibited AGG and TIMP-1 synthesis. Rhein partially reversed the effect of IL-1β on TIMP-1 and NO production, had no effect on AGG, IL-6 and MIP-1β production, but up-regulated the IL-1β stimulated PGE₂ production. The COX-2 and iNOS mRNA levels and IL-8 production were not modified by rhein.

Overall, these results contribute to explain the clinical efficiency of rhein and give new information on its mechanisms of action.

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Osteoarthritis (OA) is a disease of high ethical and economical importance. In advanced stages, the patients suffer from severe pain and restriction of mobility. The consequence in many cases is an inability to work and often the substitution of the diseased joint with an artificial implant becomes inevitable. As cartilage tissue itself has only very limited capacities of self-renewing, the development of this disorder is chronic and progressive. Generally, OA is diagnosed in more advanced stages, when clinical and radiographic signs become evident. At this time point the options for therapeutic intervention without surgery are limited. It is, therefore, crucial to know about the basic incidents in the course of OA and especially in early stages to develop new diagnostic and therapeutic strategies. Numerous studies on human osteoarthritic tissue and in animal models have addressed various aspects of OA progression to get a better understanding of the pathophysiology of this disease. This review presents an overview on different aspects of OA research and the cellular and molecular alterations in degenerating cartilage.

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Tendon orientations in knee models are often taken from cadaver studies. The aim of this study was to investigate the effect of muscle activation on tendon orientation in vivo. Magnetic resonance imaging (MRI) images of the knee were made during relaxation and isometric knee extensions and flexions with 0°, 15° and 30° of knee joint flexion. For six tendons, the orientation angles in sagittal and frontal plane were calculated. In the sagittal plane, muscle activation pulled the patellar tendon to a more vertical orientation and the semitendinosus and sartorius tendons to a more posterior orientation. In the frontal plane, the semitendinosus had a less lateral orientation, the biceps femoris a more medial orientation and the patellar tendon less medial orientation in loaded compared to unloaded conditions. The knee joint angle also influenced the tendon orientations. In the sagittal plane, the patellar tendon had a more anterior orientation near full extension and the biceps femoris had an anterior orientation with 0° and 15° flexions and neutral with 30° flexions. Within 0° to 30° of flexion, the biceps femoris cannot produce a posterior shear force and the anterior angle of the patellar tendon is always larger than the hamstring tendons. Therefore, co-contraction of the hamstring and quadriceps is unlikely to reduce anterior shear forces in knee angles up to 30°. Finally, inter-individual variation in tendon angles was large. This suggests that the amount of shear force produced and the potential to counteract shear forces by co-contraction is subject-specific.

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Bell DR, Padua DA, Clark MA. Muscle strength and flexibility characteristics of people displaying excessive medial knee displacement.

Objective

To determine differences in strength and range of motion (ROM) between participants who exhibit medial knee displacement (MKD) during a squat that is corrected by a heel lift and those who do not.

Design

Case control.

Setting

Sports medicine research laboratory.

Participants

Thirty-seven healthy subjects (control, 19; MKD, 18) with no lower-extremity injury in the past 6 months volunteered to participate.

Interventions

Not applicable.

Main Outcome Measures

Peak force was measured in newtons using a hand-held dynamometer and passive ROM was measured in degrees with a goniometer. Separate multivariate analyses of variance were used to determine differences in strength and ROM between groups. Post hoc testing was used to elucidate differences between groups.

Results

The MKD group had the following: greater hip external rotation strength (P=.03), increased hip extension strength (P=.01), less plantarflexion strength (P=.007), and increased hip external rotation ROM (P=.008).

Conclusions

The MKD group exhibited tight and weak ankle musculature. Interventions focusing on improving strength and ROM of the ankle may improve kinematics during a squat.

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Chan DK, Lonsdale C, Ho PY, Yung PS, Chan KM. Patient motivation and adherence to postsurgery rehabilitation exercise recommendations: the influence of physiotherapists' autonomy-supportive behaviors.

Objective

To investigate the impact of physiotherapists' autonomy-supportive behaviors on patients' motivation and rehabilitation adherence after anterior cruciate ligament (ACL) reconstruction surgery.

Design

Retrospective study.

Setting

Outpatient orthopedic clinic of a university medical center.

Participants

Postsurgery ACL reconstruction patients (N=115; minimum postsurgery interval, 6mo; mean ± SD postsurgery interval, 1.77±0.8y).

Interventions

Not applicable.

Main Outcome Measures

Questionnaires measuring autonomy support from physiotherapists (Health Care Climate Questionnaire), treatment motivation (Treatment Self-Regulation Questionnaire), and rehabilitation adherence (adapted from the Sport Injury Rehabilitation Adherence Scale and the Patient Self-Report Scales of Their Home-Based Rehabilitation Adherence).

Results

Structural equation modeling analyses revealed that patients' treatment motivation mediated the relationship between physiotherapists' autonomy-supportive behaviors and rehabilitation adherence. Autonomy-supportive behavior positively predicted autonomous treatment motivation (β=.22, P<.05). Rehabilitation adherence (R²=.28) was predicted positively by autonomous motivation (β=.64, P<.05) and negatively predicted by controlled motivation (β=−.28, P<.05).

Conclusions

These preliminary findings are promising and provide an empirical basis for further research to test the efficacy of autonomy support training designed to increase patients' rehabilitation adherence.

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Background. Computer-assisted surgery is useful to increase the precision of anterior cruciate ligament (ACL) surgical procedure, but could be even more important in evaluating the global performance of reconstructed ACL. This paper describes a new protocol for an accurate and extensive computer-assisted evaluation of single- and double-bundle reconstructions of ACL.

Methods. The protocol consists of the acquisition of the leg axes, ACL and graft insertions by a navigation system, and tracking of the knee motion during the classical kinematic test of knee stability. These data are elaborated by computer software in order to compute graft biomechanical behaviour and the knee kinematics and estimate the performance of the intervention.

Findings. The proposed protocol was validated on three cadaver knees. It resulted minimally invasive, effective to describe graft kinematic performance and able to provide a 3D reliable description of the reconstructed knee.

Interpretation. The protocol is an extension of the present evaluation of computer-assisted packages and includes additional kinematic tests and computations. The scientist–reader can find important details on tested computations to implement a similar computer-assisted procedure for new applications in knee surgery, while the surgeon can find in this procedure a means to improve the evaluation of ACL reconstruction and identify the residual laxity.

▼ In competitive alpine ski racing, the knee joint is exposed to exalted loadings and therefore at high risk for overloadings, which is mirrored by the persistently high incidence of knee injuries. However, causative factors and mechanisms for specific knee injuries, e.g. anterior cruciate ligament (ACL) ruptures, are multifactorial. Indeed, previously performed strategies for prevention of especially ruptures of the ACL have not been successfully implemented in professional alpine ski racing to reduce the incidence of these injuries. It seems mandatory in the future, that novel approaches at different levels must be considered to overcome these complex problems.

▼ In competitive alpine ski racing, the knee joint is exposed to exalted loadings and therefore at high risk for overloadings, which is mirrored by the persistently high incidence of knee injuries. However, causative factors and mechanisms for specific knee injuries, e.g. anterior cruciate ligament (ACL) ruptures, are multifactorial. Indeed, previously performed strategies for prevention of especially ruptures of the ACL have not been successfully implemented in professional alpine ski racing to reduce the incidence of these injuries. It seems mandatory in the future, that novel approaches at different levels must be considered to overcome these complex problems.

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The aims of this study were to predict and explain the patterns of ligament forces in the stump of a left trans-tibial amputee during walking, and to study the effects of the prosthetic alignment. Musculoskeletal modeling and computer simulation were combined to calculate ligament forces. The prosthesis was aligned to be in optimal position for the subject and then changed by ±6° in the sagittal plane. The results showed most ligaments bearing the maximum tension forces around both heel-strike and toe-off. The PT force was the biggest in all of the ligaments which were studied. The load patterns of ACL and PCL were opposite in the gait cycle, but the load patterns of MCL and LCL appeared similar. The above results showed that the ligament forces increased at the incorrect alignment, because the incorrect alignment could break the relative translation of the femur and tibia, and that would generate the extra ligament strains. As a result, the ligament forces increased, and the long-duration fatigue occurred more easily. This finding suggests that the proper prosthetic alignment is very important for the normal activities of the stump ligaments.

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Hurley ST, Hatfield Murdock GL, Stanish WD, Hubley-Kozey CL. Is there a dose response for valgus unloader brace usage on knee pain, function, and muscle strength?

Objective

To examine whether there was a dose response for valgus unloader brace wear on knee pain, function, and muscle strength in participants with medial compartment knee osteoarthritis.

Design

In this single-group study, participants with medial compartment knee osteoarthritis were followed for approximately 6 months.

Setting

Recruitment was conducted in the general community, and testing was performed at a university laboratory.

Participants

A convenience sample of patients (N=32) who were prescribed a valgus unloader brace agreed to participate, met the inclusion criteria, and completed the baseline data collection. Twenty-four participants (20 men, 4 women) completed baseline and follow-up collections.

Intervention

Participants wore their valgus unloader brace as needed.

Main Outcome Measures

Knee extensor, flexor, and plantar flexor strength was tested at baseline and follow-up. Participants filled out Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Medical Outcomes Study 36-Item Short-Form Health Survey questionnaires to assess pain and function. Self-selected walking velocity and stride length were objective measures of function. Brace usage (dose) and activity (step count) were recorded at least 4 days/week for the study duration.

Results

Positive relationships existed between brace wear usage and percent change in step count (r=.59, P=.006) and percent change in hamstrings strength (r=.37, P=.072). At follow-up, there was significant improvement in hamstrings strength (P=.013), and trends toward improvements in WOMAC pain (P=.059) and WOMAC function (P=.089).

Conclusions

Our results indicate that greater brace use may positively affect physical activity level, but there was minimal effect of brace wear dosage on lower-limb muscle strength. Only knee flexion showed a positive relationship. Our finding of no decreased muscle strength indicates that increased brace use over a 6-month period does not result in muscle impairment.

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Achieving anatomical graft placement remains a concern in Anterior Cruciate Ligament (ACL) reconstruction. The purpose of this study was to quantify the effect of femoral graft placement on the ability of ACL reconstruction to restore normal knee kinematics under in vivo loading conditions. Two different groups of patients were studied: one in which the femoral tunnel was placed near the anterior and proximal border of the ACL (anteroproximal group, n=12) and another where the femoral tunnel was placed near the center of the ACL (anatomic group, n=10)

MR imaging and biplanar fluoroscopy were used to measure in vivo kinematics in these patients during a quasi-static lunge. Patients with anteroproximal graft placement had up to 3.4mm more anterior tibial translation, 1.1mm more medial tibial translation and 3.7° more internal tibial rotation compared to the contralateral side. Patients with anatomic graft placement had motion that more closely replicated that of the intact knee, with anterior tibial translation within 0.8mm, medial tibial translation within 0.5mm, and internal tibial rotation within 1°.

Grafts placed anteroproximally on the femur likely provide insufficient restraint to these motions due to a more vertical orientation. Anatomical femoral placement of the graft is more likely to reproduce normal ACL orientation, resulting in a more stable knee. Therefore, achieving anatomical graft placement on the femur is crucial to restoring normal knee function and may decrease the rates of joint degeneration after ACL reconstruction.

▼ 

Biomechanical stimuli have fundamental roles in the maintenance and remodeling of ligaments including collagen gene expressions. Mechanical stretching signals are mainly transduced by cell adhesion molecules such as integrins. However, the relationships between stress-induced collagen expressions and integrin-mediated cellular behaviors are still unclear in anterior cruciate ligament cells. Here, we focused on the stretch-related responses of different cells derived from the ligament-to-bone interface and midsubstance regions of human anterior cruciate ligaments. Chondroblastic interface cells easily lost their potential to produce collagen genes in non-stretched conditions, rather than fibroblastic midsubstance cells. Uni-axial mechanical stretches increased the type I collagen gene expression of interface and midsubstance cells up to 14- and 6-fold levels of each non-stretched control, respectively. Mechanical stretches also activated the stress fiber formation by shifting the distribution of integrin αVβ3 to the peripheral edges in both interface and midsubstance cells. In addition, integrin αVβ3 colocalized with phosphorylated focal adhesion kinase in stretched cells. Functional blocking analyses using anti-integrin antibodies revealed that the stretch-activated collagen gene expressions on fibronectin were dependent on integrin αVβ3-mediated cellular adhesions in the interface and midsubstance cells. These findings suggest that the integrin αVβ3-mediated stretch signal transduction might have a key role to stimulate collagen gene expression in human anterior cruciate ligament, especially in the ligament-to-bone interface.

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Knee laxity has been shown to increase during human pregnancy, and the laxity of the rabbit medial collateral ligament also increases during pregnancy. To determine whether the changes in tissue function could be related to alterations in the regulation of gene expression for a subset of relevant molecules in ligaments, RNA was isolated from the medial collateral(MCL) and anterior cruciate(ACL) ligaments of first time pregnant adolescent rabbits. Levels of mRNA for matrix molecules (collagen types I and III and the proteoglycans biglycan, decorin, verisican and lumican), proteinases and inhibitors (collagenase, urokinase, PAI-1 and TIMP-1, -2 and -3), growth factors (bFGF, IGF-I, TGF-β1 and ET-1), cytokines (IL-1β and TNF) and enzymes responsible for important tissue mediators (COX-2 and iNOS) were assessed by semi-quantitative RT-PCR. In the MCL, levels of transcripts for all of the matrix molecules, growth factors and TIMPs 1 and 2 were significantly depressed at 29 days of pregnancy compared to age-matched non-pregnant controls. In contrast, transcripts for PAI-1 were elevated during pregnancy, while those for collagenase (MMP-1), urokinase, TIMP-3, IL-1β, TNF, COX-2 and iNOS were not statistically altered. mRNA transcript levels rebounded by 7 days post-partum for most genes studied, indicating that the changes were rapidly reversible. For some molecules, transcript levels were again depressed at 18 days post-partum, indicating that regulatory mechanisms were still not stabilized. Analysis of mRNA from the ACL also revealed changes in the pattern of gene expression, with some similarilties and differences from the MCL noted. These results indicate that pregnancy induces reversible changes in mRNA for matrix molecules in ligaments, but differences in responsiveness exist between different ligaments. The complexity of the changes observed indicates that there is probably no simple cause and effect relationship between laxity changes and the molecular alterations during pregnancy.

▼ 

Despite recent attention in the literature, anterior cruciate ligament (ACL) injury mechanisms are controversial and incidence rates remain high. One explanation is limited data on in vivo ACL strain during high-risk, dynamic movements. The objective of this study was to quantify ACL strain during jump landing. Marker-based motion analysis techniques were integrated with fluoroscopic and magnetic resonance (MR) imaging techniques to measure dynamic ACL strain non-invasively. First, eight subjects’ knees were imaged using MR. From these images, the cortical bone and ACL attachment sites of the tibia and femur were outlined to create 3D models. Subjects underwent motion analysis while jump landing using reflective markers placed directly on the skin around the knee. Next, biplanar fluoroscopic images were taken with the markers in place so that the relative positions of each marker to the underlying bone could be quantified. Numerical optimization allowed jumping kinematics to be superimposed on the knee model, thus reproducing the dynamic in vivo joint motion. ACL length, knee flexion, and ground reaction force were measured. During jump landing, average ACL strain peaked 55±14ms (mean and 95% confidence interval) prior to ground impact, when knee flexion angles were lowest. The peak ACL strain, measured relative to its length during MR imaging, was 12±7%. The observed trends were consistent with previously described neuromuscular patterns. Unrestricted by field of view or low sampling rate, this novel approach provides a means to measure kinematic patterns that elevate ACL strains and that provide new insights into ACL injury mechanisms.

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An increasing number of anterior cruciate ligament (ACL) injuries are seen in children now than in the past due to increased sports participation. The natural history of ACL deficient knees in active individuals, particularly in children is poor. Surgical management of ACL deficiency in children is complex due to the potential risk of injury to the physis and growth disturbance. Delaying ACL reconstruction until maturity is possible but risks instability episodes and intra-articular damage. Surgical options include physeal-sparing, partial transphyseal and complete transphyseal procedures. This article reviews the management of ACL injured skeletally immature patients including the functional outcome and complications of contemporary surgical techniques.

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Zusammenfassung

Die gevierfachte Semitendinosussehne wird von einigen Autoren als gleichwertiger Ersatz zum Patellarsehnentransplantat zur Rekonstruktion des vorderen Kreuzbands empfohlen. Einige klinische Fehlschläge mit diesem Transplantat veranlaßten uns, das primäre Transplantatkonstrukt biomechanisch zu untersuchen. Es war unsere Hypothese, daß infolge repetitiver, zyklischer Belastung eine viskoplastische Längenzunahme im Transplantatkonstrukt auftritt. 8 Semitendinussehnen von Leichengeweben wurden in der klinisch angewandten Technik zu einem Vierfachtransplantat präpariert. Zur proximalen Verankerung dienten ein Polyesterband und ein Titanplättchen. Die freien Sehnenenden wurden zur späteren distalen Fixierung mit Fäden um eine kortikale Fixierungsschraube angeschlungen. Das Titanplättchen und eine distale Kortikalisschraube wurden fest mit einer mechanischen Prüfmaschine zur weiteren Testung verbunden. Der Abstand der Fixierungspunkte lag bei 120 mm. Nach Präkonditionierung erfolgte das Knoten der Fäden bei maximaler Spannung. Es erfolgte zunächst eine Serie aus 5 zyklischen Belastungtests zwischen 20 und 100N (Test A) oder 20 und 150N (Test B). Die Testfolge war A₁-A₂-B₁-B₂-A₃ mit einer 1stündigen Entlastung der Konstrukte zur möglichen Rückbildung viskoelastischer Effekte. Nach jeder Entlastungphase erfolgte eine Längenmessung bei 3N Vorspannung. Während der zyklischen Belastung wurde mit einer digitalen Videoanalyse die relative Bewegung innerhalb von 3 Abschnitten des Konstrukts bestimmt. Abschließend erfolgte ein Zerreißtest. In Folge der zyklischen Belastung kam es zu einer durchschnittlichen viskoplastischen Längenzunahme der Transplantatkonstrukte von 3,9 ± 0,9 mm. Nur ca. 3% dieser Längenzunahme fanden im Bereich des Sehnengewebes statt. Alle Konstrukte versagten durch Zerreissen des Mersilenebands bei einer Maximallast von 416 ± 36N. Die Steifigkeit lag bei 32,4 ± 1,3N/mm. Die Ergebnisse stützen die Hypothese, daß eine beträchtliche viskoplastische Längenzunahme in den Transplantatkonstrukten infolge zyklischer Belastung auftritt. Ähnliche Belastungen können in den Transplantatkonstrukten bei Kniebelastungen in der frühen postoperativen Phase auftreten und Ursache für eine Auslockerung vor Einheilung in den Knochenkanal sein. Wir schließen aus unseren Ergebnissen, daß eine aggressive Rehabilitation bei Verwendung dieser Technik nicht empfohlen werden kann. Verbesserte Techniken und/ oder Materialien zur Verankerung der Semitendinosusessehnen sollten entwickelt werden, um das biomechanische Verhalten der Transplantatkonstrukte zu verbessern.

Summary

The purpose of this study was to determine the viscoplastic deformation in a quadrupled semitendinosus graft construct using a titanium button/ tape and screw post/suture fixation technique in response to cyclic loading. Eight quadrupled grafts for replacement of the anterior cruciate ligament (ACL) were prepared from human cadaveric semitendinosus tendons. For fixation, a polyester tape attached to a titanium button and four #2 nonresorbable sutures attached to each of the four tendon ends tied around a post screw were used. The graft construct was mounted on an INSTRON testing machine, with the titanium button and the post screw rigidly fixed at a constant distance of 120 mm. Cyclic creep tests (with 100 cycles each) were performed (A) between 20 and 100 N and (B) between 20 and 150 N (Fig. 1). The test sequence was A₁-A₂-B₁-B₂-A₃ with a rest period of 1 h between single tests for graft recovery. The length of the graft construct after each rest period was used to determine the permanent elongation. Relative length changes along the graft construct (proximal, central, distal) were determined using a video tracking device. Finally, a load-to-failure test was performed. Under all test conditions the maximum elongation of the graft construct increased from the first to the 100th cycle, ranging from 1.0 mm to 3.1 mm. While these so-called creep patterns were almost identical in A₁ and A₂, elongations under A₃ were 3–4 mm higher than under A₁ and A₂, probably as a result of higher loads at B₁ and B₂. The permanent elongation of the graft constructs after completion of the test series was 3.9 ± 0.9 mm. Further analysis revealed that about 97% of this deformation occurred within the fixation materials and interfaces (distal and proximal section) and only about 3% within the tendon tissue (central section). The load-to-failure test revealed an ultimate load of 416 ± 36 N and a stiffness of 32.4 ± 1.3 N/mm. All constructs failed at the polyester tape. Our results indicate that repetitive cyclic loading at relatively low loads can result in substantial, permanent elongation of a quadrupled semitendinosus graft construct with endobutton/tape and suture/post screw fixation method. Similar loads may be experienced by the graft construct during early postoperative activities and be a cause of gradual failure before graft incorporation is complete. We conclude that aggressive postoperative rehabilitation be applied with caution when using this graft construct. Better fixation materials and/ or techniques should be developed to improve biomechanical behavior of the graft construct.

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Zusammenfassung

Die Behandlung der vorderen Kreuzbandruptur war in den vergangenen 30 Jahren erheblichen Wandlungen unterworfen. Nach einer Periode der direkten Naht und extraartikulärer Stabilisierungsverfahren folgte wegen der unbefriedigenden Ergebnisse dieser Methoden eine Phase der konservativen Therapie. Die hohe Rate instabilitätsbedingter Meniskusschäden und Arthrosen ließ das Pendel aber wieder in Richtung operativer Verfahren umschlagen. Die Langzeitresultate nach alleiniger direkter Naht sind allerdings nicht besser geworden als früher, auch wenn die Morbidität heute aufgrund neuer Zugangswege deutlich geringer ist. Dagegen hat sich die Kreuzbandplastik mit autologer Patellarsehne oder Semitendinosussehne mit guten Ergebnissen als Therapiestandard auch für die Versorgung frischer Bandverletzungen etabliert. Modifikationen des Operationszeitpunkts und der Rehabilitation haben die Komplikationsrate gesenkt und die Resultate noch verbessert. Erkenntnisse der Neuroanatomie und Neurophysiologie des Kreuzbands lassen heute eine veränderte Nahttechnik mit Augmentation durch autologe oder auch resorbierbare Materialien sinnvoll erscheinen. Die Ergebnisse sprechen dafür, daß die Aufrechterhaltung der propriozeptiven Funktion nicht nur theoretisch eine dauerhafte Stabilisierung ermöglicht.

There have been quite frequent changes in the treatment of anterior cruciate ligament lesions in the course of the last 30 years. A period of direct suturing and extraarticular stabilizing procedures with unsatisfactory results was followed by an era of conservative treatment, but the high incidence of degenerative lesions and menisceal tears caused by instability led to a trend for more reconstructive surgical procedures. The long-term results of direct suturing have not improved, although postoperative morbidity has, because of new techniques for exposure. But anterior cruciate ligament reconstruction with semitendinosus or patellar tendon grafts has become established as a standard technique with good results also in the treatment of acute ligament tears. Modifications concerned with the timing of surgery and rehabilitation reduced the risk of complications and improved the outcome. New insights into the neuroanatomy and neurophysiology of the cruciate ligaments have led to a combination of direct suturing and augmentation with autologous or bioresorbable material. The good results seem to confirm that with maintenance of the proprioceptive function the achievement of long-term stability is not only theoretically possible.

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Zusammenfassung

Kniegelenknahe Flexions- oder Extensionsosteotomien sind seltene Eingriffe. Die Indikation zur operativen Behandlung eines solchen Kniegelenks ist abhängig von der funktionellen Beeinträchtigung und hierbei insbesondere der Instabilität des Kniegelenks bei Belastung (seltener wegen Schmerzen), dem klinischen und dem radiologischen Befund. Dem knöchernen Eingriff zur Korrektur der Deformität ist in einigen Fällen eine periphere oder zentrale Bandplastik des Kniegelenks hinzuzufügen.

Zur präoperativen Abklärung ist eine eingehende röntgenologische Abklärung unabdingbar. Hier muss eine beginnende Arthrose ausgeschlossen und die Neigung des Tibiaplateaus bestimmt werden. Darüber hinaus führen wir routinemäßig gehaltene Aufnahmen zur Bestimmung der vorderen und hinteren Schublade durch. Im Falle einer begleitenden vorderen oder hinteren Kreuzbandruptur sollte die Notwendigkeit einer begleitenden Bandplastik mit diskutiert werden.

The present review analyzes the rare indications for sagittal knee osteotomies either for some complex cases of capsular and ligamentous laxities in combination with or without bony deformities in the sagittal plane. A thorough clinical and radiological analysis of the patients’ knees is mandatory.

We routinely recommend lateral standing X-rays to assess not only the bony structures, but also an abnormal knee laxity in the sagittal plane. We present different surgical options and preliminary results of these technically demanding procedures.

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Zusammenfassung

Komplexe vordere Instabilitäten umfassen neben dem vorderen Kreuzband (VKB) mindestens eine wesentliche Bandstruktur (mediales und laterales Seitenbandsystem, hinteres Kreuzband, HKB). Verletzungen der medialen Seite haben eine hohe Heilungspotenz und können meist konservativ/funktionell behandelt werden, sofern eine Rekonstruktion des VKB erfolgt. Indikationen zur operativen Bandnaht sind die Instabilität der Meniskusaufhängung, die Luxation der Bandfasern in das Gelenk, die Kniezerreissung mit vollständigem Verlust der Stabilität und der große dislozierte knöcherne Ausriss. Der dreischichtige Aufbau des medialen Bandkomplexes muss bei der operativen Versorgung berücksichtigt werden. Bandrupturen auf der Lateralseite des Kniegelenks neigen zur Retraktion und heilen spontan nicht suffizient. Bei relevanter Instabilität sollte der laterale Bandapparat daher anatomisch rekonstruiert werden. Bandnähte auf der Medial- und Lateralseite sollten in den ersten 14 Tagen nach Trauma durchgeführt werden, da später eine anatomische Präparation nicht mehr gelingt. Kniezerreissungen und manifeste Luxationen sollten stets in Repositionsstellung des Gelenks ruhig gestellt werden. Eine sorgfältige Abklärung des Gefäßstatus ist insbesondere bei hinterer Luxation der Tibia erforderlich. Eine operative Frühversorgung in den ersten 2 Wochen mit Rekonstruktion beider Kreuzbänder und ggf. des Seitenbandsystems sowie frühfunktioneller Nachbehandlung hat sich in einer großen Europäischen Multicenterstudie im Vergleich zu einer konservativ/immobilisierenden Behandlung als günstig erwiesen.

Complex knee instability involves the anterior cruciate ligament (ACL) and one or more major stabilizers of the knee [medial collateral ligament (MCL), lateral collateral ligament (LCL), posterior cruciate ligament (PCL)]. The medial side has a high healing potential and does not need operative treatment in most cases if ACL reconstruction is performed. Reconstruction of the medial ligament complex is indicated in gross instability of the medial meniscus fixation, dislocation of the MCL into the joint, and large dislocated bony avulsions. Injuries on the lateral side do not heal spontaneously and require acute operative treatment (first 2 weeks). Frank knee dislocations and gross multiligament injuries should be reduced acutely, and the integrity of the vascular structures must be examined closely. In a European multicenter study, operative treatment with reconstruction of both cruciate ligaments and functional rehabilitation gave better results than conservative treatment with immobilization of the joint.

▼ Background and Objectives

This prospective randomized controlled trial investigated the clinical efficacy of stimulating catheters for continuous femoral nerve block in patients who underwent anterior cruciate ligament reconstruction.

Methods

Seventy patients were randomized to either a stimulating catheter (SC, n = 35) or a nonstimulating catheter (NSC, n = 35) for femoral nerve block using 25 mL ropivacaine 7.5 mg/mL and clonidine 50 μg injected through the catheter. A single-injection sciatic block was also given to ensure surgical anesthesia. The time to loss of sensation to cold and pinprick of the femoral nerve was registered as the onset time. Data were registered intra- and postoperatively regarding pain scores, adverse effects, and need for supplemental anesthesia and analgesia other than a continuous postoperative infusion of ropivacaine 2 mg/mL through the continuous femoral nerve catheter set at 7 mL/h.

Results

Onset time was faster in the SC group (SC: 6.4 ± 2.5, NSC: 8.3 ± 2.9 min, P = .006). Visual analog scale pain scores were similar in both groups. The number of patient-controlled regional analgesia boluses (SC: 14.6 ± 12.6, NSC: 23.2 ± 13.6 mg ropivacaine 2 mg/mL, P = .008) as well as intravenous rescue ketorolac (SC: 34.3 ± 35.7, NSC: 54 ± 39.7 mg, P = .033) administered were higher in the NSC group.

Conclusion

Although the use of a stimulating catheter was associated with faster onset time for the femoral nerve block and lower additional analgesics postoperatively, the clinical superiority (analgesia; lateral femoral cutaneous, and obturator nerve block) of stimulating catheters was not evident in this clinical setting.