The Management Of Meniscal Tears In The ACL-Deficient Knee

Anterior cruciate ligament reconstruction with concomitant meniscal surgery: a systematic review and meta-analysis of outcomes

PURPOSE

The aim of this review was to compare the clinical outcomes of anterior cruciate ligament reconstruction (ACLR) with either meniscal repair or meniscectomy for concomitant meniscal injury. The primary hypothesis was that short-term clinical outcomes (≤ 2-year follow-up) for ACLR concomitant with either meniscal repair or resection would be similar. The secondary hypothesis was that ACLR with meniscal repair would result in better longer term outcomes compared with meniscal resection.

METHODS

The authors searched two online databases (EMBASE and MEDLINE) from inception until March 2018 for the literature on ACLR and concurrent meniscal surgery. Two reviewers systematically screened studies in duplicate, independently, and based on a priori criteria. Quality assessment was also performed in duplicate. The Knee injury and Osteoarthritis Outcome Score (KOOS) sub-scale scores at 2 years post-operatively were combined in a meta-analysis of proportions using a random-effects model.

RESULTS

Of 2566 initial studies, 25 studies satisfied full-text inclusion criteria. Mean follow-up was 2.09 years, with a total sample of 37,087 subjects including controls. The meta-analysis demonstrated equivocal results at 2 years, except for KOOS symptom scores which favoured meniscal resection over repair. Mean KT-1000 side-to-side difference (SSD) scores were 1.51 ± 0.60 mm for meniscal repair, 1.96 ± 0.36 mm for meniscal resection, and 1.58 ± 0.20 for control patients (isolated ACLR). Medial meniscal repair showed decreased anterior knee joint laxity compared to medial meniscal resection (P < 0.001). Patients with meniscal repair had higher rates of re-operation (13.3% vs 0.8% for meniscal resection, P < 0.001).

CONCLUSION

Patients with ACLR combined with meniscal resection demonstrate better symptoms at 2-year follow-up compared to patients with ACLR combined with meniscal repair. ACLR combined with meniscal repair results in decreased anterior knee joint laxity with evidence of improved patient-reported outcomes in the long term, but also higher re-operation rates.

LEVEL OF EVIDENCE

III.

Second-Look Arthroscopic Evaluations of Meniscal Repairs Associated With Anterior Cruciate Ligament Reconstruction

PURPOSE

To examine the healing status of meniscal repair performed concomitantly with anterior cruciate ligament (ACL) reconstruction with our current indication and surgical procedure based on second-look arthroscopic results. Additionally, the significance of the demographic and clinical factors that can potentially influence the healing rate was statistically assessed.

METHODS

Between January 2009 and January 2015, second-look was performed for patients who opted to have tibial screw removal and agreed to have concomitant arthroscopy. The healing status of the repaired meniscus was classified into 3 conditions: healed, incompletely healed, and not healed. In addition, clinical outcomes were evaluated at a minimal 1-year follow-up. The effects of patient factors on the meniscal healing rate were statistically assessed.

RESULTS

A total of 217 knees underwent arthroscopic meniscal repair concomitant with ACL reconstruction, while second-look was performed for 105 knees. The average period from index surgery to second-look was 15.0 months. Clinical evaluation was conducted at a mean of 17 months (12-50 months). Based on the second-look arthroscopic findings, 64 menisci, 22 menisci, and 29 menisci were categorized as healed, incompletely healed, and not healed, respectively. When the not healed condition was defined as failed repair, a Tegner activity score of 8 or more, recurrent instability, tears in the red-white to white-white zones, and time from injury to surgery of 4 months or longer were identified as clinical factors significantly correlated with failure (P < .01).

CONCLUSIONS

Meniscal repair in ACL reconstructed knees with expanded indications achieved a healing rate (including incomplete healing) of 75%. Clinical factors such as high sports activity level, recurrent ACL instability, poor vascularity of the repaired site, and long duration from injury to surgery were shown to impair the healing status.

LEVEL OF EVIDENCE

Level Ⅳ, therapeutic study, case series.

Comparative Outcomes of Radial and Bucket-Handle Meniscal Tear Repair: A Propensity-Matched Analysis

BACKGROUND

Full-thickness radial meniscal tears render the meniscus nonfunctional and have historically been treated with partial meniscectomy. As preservative techniques evolve for radial repair, comparisons with other tear patterns are necessary to evaluate repair efficacy and prognosis.

PURPOSE

To assess clinical outcomes and reoperation rates of radial meniscal repair and to compare them to bucket-handle meniscal repair.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Radial and bucket-handle meniscal tears without concurrent root injuries undergoing surgical repair at a single institution between 2007 and 2015 were analyzed, including both all-inside and inside-out suturing techniques. Propensity matching was performed on the basis of age at surgery, sex, meniscus laterality, body mass index (BMI), and concomitant anterior cruciate ligament reconstruction (ACLR) using a comparison pool of 70 bucket-handle repairs. Reoperation-free survival rates and Tegner, visual analog scale (VAS) for pain, and International Knee Documentation Committee (IKDC) scores were analyzed.

RESULTS

Twenty-four patients (18 male, 6 female; mean age, 22.8 ± 11.9 years) who underwent repair of a radial meniscal tear were followed for a mean of 3.5 years (range, 2.0-6.3 years). Significant postoperative improvements in VAS scores at rest and with use and IKDC scores were noted postoperatively ( P < .001). Five patients (20.8%) required a reoperation. Subsequently, 18 patients with radial tears (mean age, 19.1 ± 9.1 years; 12 male; mean BMI, 27.0 ± 6.2 kg/m²; 3 medial; 11 ACLR) were propensity matched to 18 patients with bucket-handle tears (mean age, 20.8 ± 5.1 years; 13 male; mean BMI, 25.0 ± 3.5 kg/m²; 3 medial; 11 ACLR). The matched radial and bucket-handle groups demonstrated similar ( P = .17) reoperation-free survival rates at 2 years (88.9% and 94.4%, respectively) and 5 years (77.8% and 87.7%, respectively). VAS and IKDC scores improved significantly after surgery ( P < .001), with no difference noted between the groups ( P ≥ .17). Patients with radial and bucket-handle meniscal repairs achieved mean postoperative Tegner scores (6.6 and 6.6, respectively) not significantly different from their preinjury levels (6.9 and 6.7, respectively) ( P ≥ .32).

CONCLUSION

Satisfactory clinical outcomes are achievable for radial meniscal tear repair at short-term follow-up. In a robustly matched comparison, radial and bucket-handle meniscal tears demonstrate similar improvements in VAS and IKDC scores, restoration of preoperative Tegner scores, and acceptable reoperation rates. Full-thickness radial meniscal tears should be considered for repair.

All-inside meniscal repair devices and techniques

Techniques and devices for meniscal repair are evolving, including for all-inside meniscal repair. The first-generation all-inside meniscal repair devices were simplistic in design, but their technical difficulties and risks led to the development of second-generation devices. These devices employed the suture anchor concept for repair and confirmed the safety of use through standard anterior arthroscopic portals. Third-generation devices introduced the idea of rigid, bioabsorbable materials; unfortunately, these demonstrated higher failure and complication rates compared with other repair techniques. They were also limited in their ability to adjust compression and tension across the repair. Now, fourth-generation devices have been developed that are flexible, suture-based, and allow for variable compression and retensioning across the tear. Each device has its own specifications and technical nuances. With a comprehensive understanding of the current devices available, the industry and surgeons may continue in the development of safer, more successful, user-friendly and cost-effective all-inside devices.

The knee meniscus: structure-function, pathophysiology, current repair techniques, and prospects for regeneration

Extensive scientific investigations in recent decades have established the anatomical, biomechanical, and functional importance that the meniscus holds within the knee joint. As a vital part of the joint, it acts to prevent the deterioration and degeneration of articular cartilage, and the onset and development of osteoarthritis. For this reason, research into meniscus repair has been the recipient of particular interest from the orthopedic and bioengineering communities. Current repair techniques are only effective in treating lesions located in the peripheral vascularized region of the meniscus. Healing lesions found in the inner avascular region, which functions under a highly demanding mechanical environment, is considered to be a significant challenge. An adequate treatment approach has yet to be established, though many attempts have been undertaken. The current primary method for treatment is partial meniscectomy, which commonly results in the progressive development of osteoarthritis. This drawback has shifted research interest toward the fields of biomaterials and bioengineering, where it is hoped that meniscal deterioration can be tackled with the help of tissue engineering. So far, different approaches and strategies have contributed to the in vitro generation of meniscus constructs, which are capable of restoring meniscal lesions to some extent, both functionally as well as anatomically. The selection of the appropriate cell source (autologous, allogeneic, or xenogeneic cells, or stem cells) is undoubtedly regarded as key to successful meniscal tissue engineering. Furthermore, a large variation of scaffolds for tissue engineering have been proposed and produced in experimental and clinical studies, although a few problems with these (e.g., byproducts of degradation, stress shielding) have shifted research interest toward new strategies (e.g., scaffoldless approaches, self-assembly). A large number of different chemical (e.g., TGF-β1, C-ABC) and mechanical stimuli (e.g., direct compression, hydrostatic pressure) have also been investigated, both in terms of encouraging functional tissue formation, as well as in differentiating stem cells. Even though the problems accompanying meniscus tissue engineering research are considerable, we are undoubtedly in the dawn of a new era, whereby recent advances in biology, engineering, and medicine are leading to the successful treatment of meniscal lesions.

All-inside meniscal repair

All-inside meniscal repair has gained widespread popularity over recent years. The devices and techniques have rapidly evolved, resulting in increased ease of use and reduced surgical times and risk to the neurovascular structures. Despite these advances, inside-out suture repairs remain the current gold standard, with proven long-term results. All-inside techniques must continue to be compared to inside-out meniscal repair.

All-inside meniscal repair using a new flexible, tensionable device

BACKGROUND

A new generation of flexible all-inside meniscal repair devices is available, but clinical studies with these devices are lacking.

HYPOTHESIS

The RapidLoc has an intermediate-term meniscal healing rate that is equivalent to literature reports of inside-out suture technique in patients undergoing concurrent anterior cruciate ligament reconstruction.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Retrospective analysis was performed for 75 meniscal tears in 66 consecutive patients undergoing anterior cruciate ligament reconstruction who underwent meniscal repair with the RapidLoc. Patients with at least 2 years' follow-up were evaluated for symptoms suggestive of a meniscal tear and were assessed with the International Knee Documentation Committee form and the Knee Disorders Subjective History visual analog scale. Subjects were asked to return for a clinical examination to include evaluation for an effusion and joint line tenderness as well as McMurray test and KT-1000 arthrometry readings. Patients with symptoms consistent with meniscal repair failure underwent magnetic resonance arthrography and repeat arthroscopy.

RESULTS

Twenty patients with 21 meniscal tears were excluded, resulting in 54 meniscal tears in 46 patients. At a mean follow-up of 34.8 months, the clinical success rate for meniscal repair was 90.7% (49/54), with 5 failures requiring meniscectomy. Univariate analysis revealed predictive variables for failure: bucket-handle configuration, multiplanar tears, tear length greater than 2 cm, and chronicity longer than 3 months. Non-predictive variables included compartment, zone, ligament graft choice, gender, age, follow-up, and visual analog scale score. Analysis of healed patients revealed a negative correlation between chronicity of tear and International Knee Documentation Committee score.

CONCLUSIONS

The RapidLoc has an acceptable intermediate-term clinical healing rate in patients undergoing concurrent anterior cruciate ligament reconstruction. Predictive variables for failure should be considered during operative decision making.

Mechanical properties of articular cartilage covered by the meniscus

OBJECTIVE

To investigate the mechanical properties and morphological characteristics of articular cartilage on the tibial plateau of human knees, including the region covered by the meniscus.

DESIGN

Using a 1-mm diameter flat-ended cylindrical probe to apply a constant load (0.6 MPa) at specific sites on the tibial plateau, the mechanical properties of articular cartilage were studied using seven cadaver knees. Comparison was made between data obtained by the cartilage covered by the meniscus and that not covered. This was done for both the medial and lateral plateaus. Histological sections of the articular cartilage were also performed to study differences between cartilage from these regions of the tibial plateau.

RESULTS

Compared to cartilage that was not covered by the meniscus, the articular cartilage beneath the meniscus showed a significantly (P<0.05) larger modulus by as much as 70%, and was less thick by about 40%. Also, the subchondral bone quantity and calcified layer thickness were observed to be significantly lesser in the regions covered by the meniscus.

CONCLUSIONS

Our findings revealed a significant difference between the mechanical properties and associated structures of articular cartilage in the region covered by the meniscus compared with the articular cartilage not covered by the meniscus.

Deteriorating outcomes after meniscal repair using the Meniscus Arrow in knees undergoing concurrent anterior cruciate ligament reconstruction: increased failure rate with long-term follow-up

BACKGROUND

An increased awareness of the degenerative changes that occur in the knee after meniscectomy has led to efforts to salvage the injured meniscus. Numerous devices have been developed in an effort to provide the dual benefits of a durable meniscal repair and minimal invasiveness.

HYPOTHESIS

The Meniscus Arrow is comparable to conventional inside-out suture repair in accomplishing long-term healing of meniscal tears.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This study is an extended follow-up of an original series of 32 patients with outcomes analysis. All patients underwent meniscal repair with exclusive use of the arrow. All repairs were performed in the context of a concomitant anterior cruciate ligament reconstruction. Follow-up assessment included physical examination, arthrometry, the International Knee Documentation Committee instrument, and the Knee Disorders Subjective History visual analog scale. Intermediate follow-up at a mean of 2.3 years yielded a success rate of 90.6%. The mean follow-up in the present study has been extended to 6.6 years.

RESULTS

The extended follow-up analysis revealed a substantial attrition in the success rate of this series of patients undergoing meniscal repair with the arrow. A 90.6% success rate at a mean follow-up of 2.3 years deteriorated to 71.4% at 6.6 years.

CONCLUSION

This study provides the longest follow-up in the literature of any of the all-inside meniscal repair implants. The Meniscus Arrow demonstrated long-term meniscal healing rates inferior to those found in the literature for inside-out suture repair techniques.

Factors related to additional knee injuries after anterior cruciate ligament injury

PURPOSE

We reviewed 1,375 consecutive patients to determine whether patient gender, age at injury, or activity level at injury were related to the risk of additional knee injuries over time following anterior cruciate ligament (ACL) injury.

TYPE OF STUDY

Retrospective case series.

METHODS

Survival analysis was used to analyze the effect of each factor while statistically controlling for the effect of time from ACL injury to reconstruction.

RESULTS

The risk of meniscus injury was significantly higher among male subjects (odds ratio [OR] = 1.5, P < .001). When undergoing ACL reconstruction more than 6 months after injury, the risk of meniscus injury increased by 1.5 times for male subjects (P = .021) but increased by 3.4 times for female subjects (P < .001). The risk of meniscus injuries was significantly higher among patients undergoing ACL reconstruction more than 6 months after injury when compared with patients undergoing reconstruction within 2 weeks of injury (OR = 2.2, P < .001). The risk of articular cartilage lesions was significantly higher among patients undergoing ACL reconstruction more than 1 year after injury when compared with patients undergoing reconstruction within 2 weeks of injury (OR = 2.1, P < .001).

CONCLUSIONS

Men had a consistently higher occurrence rate of meniscus injuries than did women. The risk of meniscus injuries increased at a higher rate over time among women. The risk of meniscus injuries increases when ACL reconstruction is performed more than 6 months after injury. The risk of articular cartilage lesions increases when ACL reconstruction is performed more than 1 year after injury.

LEVEL OF EVIDENCE

Level IV, Case Series.

Nonoperative treatment of partial-thickness meniscal tears identified during anterior cruciate ligament reconstruction

The reported incidence and treatment of partial-thickness meniscal tears seen at anterior cruciate ligament (ACL) reconstruction varies widely. The success of nonoperative treatment of partial meniscal tears identified during ACL reconstruction at our institution was reviewed. All incomplete meniscal tears were treated with observation, all full-thickness tears were treated with repair or partial meniscectomy. Partial tears of the lateral meniscus were noted three times more commonly than in the medial meniscus and were seen more acutely after ACL injury than full-thickness tears. At 2-year follow-up, excellent knee function was noted when these tears were treated nonoperatively.

Magnetic Resonance Diagnosis of Meniscal Tears in Patients With Acute Anterior Cruciate Ligament Tears

OBJECTIVE

To evaluate the accuracy of magnetic resonance imaging in the diagnosis of meniscal tear in patients with acute anterior cruciate ligament tears.

METHODS

Magnetic resonance images obtained from 41 patients imaged within 6 weeks of injury who had acute anterior cruciate ligament tears identified at arthroscopy were retrospectively reviewed for meniscal tear.

RESULTS

With MR imaging the sensitivity, specificity and accuracy for diagnosing meniscal tears in the presence of acute anterior cruciate ligament tears were 71%, 93%, and 88%; for the lateral meniscal tears were 57%, 100% and 85%; and for the medial meniscal tears were 100%, 88%, 90%. All false negative cases (n = 6) involved the posterior horn of the lateral meniscus.

CONCLUSION

In the presence of acute anterior cruciate ligament tears, MRI imaging has relatively low sensitivity for detecting meniscal tears due to missed tears in the lateral meniscus.

Prospective evaluation of 1485 meniscal tear patterns in patients with stable knees

BACKGROUND

Despite emphasis on classifying meniscal tears based on healing potential of the tear, research has concentrated on unstable knees, and few reports have provided information regarding associated clinical variables in stable knees.

PURPOSE

To report on a large series of meniscal tears in stable knees that have been carefully mapped by tear shape and tear zones to allow comparison with meniscal tears in unstable knees.

STUDY DESIGN

Prospective case series, reviewed retrospectively.

METHODS

A total of 1485 meniscal tears in stable knees were evaluated. Preoperatively, each patient underwent a standardized assessment. Each tear was carefully mapped at arthroscopy. Statistical analysis was performed to determine factors that may be associated with peripheral meniscal tears.

RESULTS

The distribution and shape of tears varied significantly within the radial and circumferential zones in this stable knee population. Five prospective variables were associated with peripheral tears: gender, presence of an effusion, positive McMurray test, varus alignment, or a loss of extension more than 5 degrees.

CONCLUSIONS

Patient demographic information and physical examination can be useful in identifying patients who may have a peripheral meniscus tear.

Results of repeat meniscal repair

BACKGROUND

The efficacy of repeat repair of retorn menisci has not been demonstrated.

PURPOSE

To document clinical and radiographic results of repeat repair of retorn menisci that had previously undergone primary repair.

STUDY DESIGN

Uncontrolled retrospective review.

METHODS

Eighteen consecutive repeat meniscal repairs were performed over an 11-year period.

RESULTS

Fourteen of 18 patients (13 repeat meniscal repairs and 1 second repeat meniscal repair) had clinically intact menisci and were available for a mean follow-up of 7.33 years (range, 3.25 to 13.75). The average durability of the initial repair was 3.46 years (range, 0.17 to 14.67). Five patients sustained a tear at the site of rerepair; one underwent second repeat repair of the meniscus and the other four patients underwent partial meniscectomy. The mean Lysholm score for the remaining 14 patients was 82.1 (range, 38 to 100), and the mean Tegner score was 5.6 (range, 2 to 8). On the International Knee Documentation Committee rating scale, five knees received an overall rating of normal; six, nearly normal; and three, abnormal. Radiographs revealed grade 0 changes (normal) in five of the involved knee compartments and grade I changes (sclerosis or mild narrowing measuring 1 to 2 mm) in the remaining five.

CONCLUSIONS

Repeat repair of retorn menisci had a 72% survival rate with relief of symptoms and return to high levels of function.

Anterior cruciate ligament reconstruction in patients with or without accompanying injuries: A re-examination of subjects 5 to 9 years after reconstruction

PURPOSE

The purpose of this study was to compare the clinical and radiologic results of an anterior cruciate ligament (ACL) reconstruction in patients with an isolated ACL tear and patients with an ACL tear and accompanying injuries.

TYPE OF STUDY

A retrospective investigation.

METHODS

Seventy-two patients who did not have previous knee surgery or surgery of the contralateral knee were re-examined 5 to 9 years after the primary ACL reconstruction. The clinical assessment was made using the International Knee Documentation Committee (IKDC) evaluation system, and the Lysholm and the Marshall knee scores. Also, radiographic evaluation and isokinetic strength testing were performed. There were 34 patients (25 men and 9 women) with an isolated ACL tear (group A), and 38 patients (23 men and 15 women) with an ACL tear and accompanying injuries (group B). The mean age was 29 years (SD 9; range, 15 to 49 years) in group A, and 34 years (SD 12; range, 15 to 61 years) in group B. Bone-patellar tendon-bone autograft with mini-arthrotomy technique and screw fixation was used in all patients. Postoperative rehabilitation was also similar in both groups. In group B, 10 medial and 12 lateral (partial or subtotal) arthroscopic meniscectomies were performed at the same time as the ACL reconstruction. Also, 18 of the 19 medial collateral ligament ruptures, the 2 lateral collateral ligament ruptures, and the 1 posterior cruciate ligament rupture were treated surgically at this operation.

RESULTS

Subjectively (overall assessment, pain, swelling, and giving way of the knee) and objectively (range of motion, stability, crepitation, isokinetic strength testing, and radiological changes of the knee), the groups did not have any significant differences in the 5- to 9-year results. Also, the final evaluation results using the IKDC and the Lysholm and the Marshall knee scores were similar in both groups. However, there were significantly more subsequent knee surgeries in the injured knee in group B than in group A.

CONCLUSIONS

Our results show no large differences between patients with an isolated ACL tear and those with an ACL tear with accompanying injuries 5 to 9 years after an ACL reconstruction with a bone-patellar tendon-bone autograft. Tibiofemoral osteoarthritis was quite rare, and this may be partly attributable to the fact that the ACL reconstructions were successful, so that all the knees were stable at the re-examination. However, the future will show the final outcome for the patients.

Pathologic changes in grossly normal menisci in dogs with rupture of the cranial cruciate ligament

OBJECTIVE

To determine whether histopathologic changes are detectable in grossly normal medial menisci from dogs with rupture of the cranial cruciate ligament (CCL).

DESIGN

Case series.

SAMPLE POPULATION

40 medial menisci from dogs with rupture of the CCL and 20 medial menisci from control dogs without stifle joint disease.

PROCEDURE

Data evaluated included age, duration of clinical signs, and whether rupture of the CCL was complete or incomplete. Three groups (n = 20/group) were also compared on the basis of 5 histologic criteria; group-1 menisci appeared grossly normal and were obtained from dogs with naturally occurring rupture of the CCL, group-2 menisci were grossly abnormal and were also obtained from dogs with naturally occurring CCL ruptures, and group-3 menisci were collected at postmortem from dogs without stifle joint disease that were of similar age and weight as dogs in groups 1 and 2.

RESULTS

Group-2 menisci were significantly different from group-1 and -3 menisci in all histologic criteria. Group-1 menisci were significantly different from control menisci in only 1 of the 5 histologic criteria (cartilage differentiation). Dogs that were > or =3 years old had significantly more surface cellularity than did dogs that were < 3 years old. A significant difference was not detected between groups 1 and 2 with regard to completeness of rupture.

CONCLUSIONS AND CLINICAL RELEVANCE

Histologic changes in meniscal cartilage correlate with gross appearance of the cartilage at time of surgery for rupture of the CCL. On the basis of minimal histologic changes, routine removal of grossly normal menisci does not appear to be warranted.

Importance of the medial meniscus in the anterior cruciate ligament-deficient knee

The incidence of meniscal tears in the chronically anterior cruciate ligament-deficient knee is increased, particularly in the medial meniscus because it performs an important function in limiting knee motion. We evaluated the role of the medial meniscus in stabilizing the anterior cruciate ligament-deficient knee and hypothesized that the resultant force in the meniscus is significantly elevated in the anterior cruciate ligament-deficient knee. To test this hypothesis, we employed a robotic/universal force-moment sensor testing system to determine the increase in the resultant force in the human medial meniscus in response to an anterior tibial load following transection of the anterior cruciate ligament. We also measured changes in the kinematics of the knee in multiple degrees of freedom following medial meniscectomy in the anterior cruciate ligament-deficient knee. In response to a 134-N anterior tibial load, the resultant force in the medial meniscus of the anterior cruciate ligament-deficient knee increased significantly compared with that in the meniscus of the intact knee; it increased by a minimum of 10.1 N (52%) at full knee extension to a maximum of 50.2 N (197%) at 60 degrees of flexion. Medial meniscectomy in the anterior cruciate ligament-deficient knee also caused a significant increase in anterior tibial translation in response to the anterior tibial load, ranging from an increase of 2.2 mm at full knee extension to 5.8 mm at 60 degrees of flexion. Conversely, coupled internal tibial rotation in response to the load decreased significantly, ranging from a decrease of 2.5 degrees at 15 degrees of knee flexion to 4.7 degrees at 60 degrees of flexion. Our data confirm the hypothesis that the resultant force in the medial meniscus is significantly greater in the anterior cruciate ligament-deficient knee than in the intact knee when the knee is subjected to anterior tibial loads. This indicates that the demand on the medial meniscus in resisting anterior tibial loads is increased in the anterior cruciate ligament-deficient knee compared with in the intact knee, suggesting a mechanism for the increased incidence of medial meniscal tears observed in chronically anterior cruciate ligament-deficient patients. The large changes in kinematics due to medial meniscectomy in the anterior cruciate ligament-deficient knee confirm the important role of the medial meniscus in controlling knee stability. These findings suggest that the reduction of resultant force in the meniscus may be a further motive for reconstructing the anterior cruciate ligament, with the goal of preserving meniscal integrity.

Musculoskeletal rehabilitation and sports medicine. 3. Knee and lower extremity injuries

This self-directed learning module discusses classic concepts and highlights new advances in the diagnosis and management of knee and lower extremity injuries that commonly occur during athletic competition. It is part of the chapter on musculoskeletal rehabilitation and sports medicine in the Self-Directed Physiatric Education Program for practitioners and trainees in physical medicine and rehabilitation.