Allograft ligament transplantation in anterior cruciate ligament reconstruction patients with meniscal tears

Background

It currently remains unclear whether the meniscal repair clinical results were affected by the graft used in anterior cruciate ligament (ACL) reconstruction. This retrospective study designed to evaluate the difference in clinical outcomes of meniscal repair using autograft and allograft for the ACL reconstruction.

Methods

The injury of the ACL and meniscus was evaluated with MRI and treated simultaneously. One hundred and eighty-nine cases were initially fulfilled the study criteria, and had the surgery in the period June 2007 and July 2010. Thirty-four patients were lost to follow-up. Seventy-five patients underwent meniscus repair with autograft reconstruction of the ACL (autograft group) and 80 patients underwent meniscus repair with allograft reconstruction of the ACL (allograft group).

Results

The meniscus healing rate based on the clinical examination of Barrett’s criteria was 81.3 % (61/75) in the autograft group and 80.0 % (64/80) in the allograft (P > 0.05). There was no significant difference in the Lysholm scores in the allograft group compared to the allograft group (89.1 ± 10.6 versus 88.7 ± 11.2, P > 0.05). The values of immunoglobulin’s and complements (IgG, IgA, IgM, C3 and C4) were not significantly different between the two groups (P > 0.05).

Conclusion

The data support our assumption that patients undergoing meniscal repair associated with ACL reconstruction with allograft had good clinical outcomes. Although allograft implantation induces an immunological response on a subclinical level, there were no signs of allograft affecting the nature of meniscus healing.     

Clinical results of arthroscopic all-inside lateral meniscal repair using the Meniscal Viper Repair System

Purpose

This study examined the postoperative outcome of the all-inside arthroscopic meniscal suture repair technique using the Meniscal Viper Repair System for lateral meniscus tears.

Methods

Between January 2006 and December 2008, 57 patients (27 males and 30 females) with lateral meniscus tears who underwent meniscal repair using the Meniscal Viper Repair System were evaluated prospectively. Among them, 52 cases were tears involving the posterior third of the lateral meniscus, and most were longitudinal tears or bucket handle tears. The postoperative follow-up period ranged from 12 months to 4 years and 2 months, and averaged 19 months.

Results

Both Lysholm and Japanese Orthopaedic Association Score were significantly improved after surgery. Forty-nine of 57 patients (86.0 %) had no locking or catching, no joint line tenderness, and a negative McMurray test at the last follow-up. Of 32 patients who underwent second-look arthroscopy, 24 achieved complete healing, while four showed partial healing and required repeat repair, and four showed no healing and meniscectomy was conducted. The failure rate in all patients was thus 14.0 % (8 of 57 repairs). No major complications associated with the use of the Meniscal Viper Repair System were observed.

Conclusion

The Meniscal Viper System is a convenient and effective device for all- inside lateral meniscal suture, with high success rate and no major complications.     

Outcome of repaired unstable meniscal tears in children and adolescents

Background

Unstable meniscal tears are rare injuries in skeletally immature patients. Loss of a meniscus increases the risk of subsequent development of degenerative changes in the knee. This study deals with the outcome of intraarticular meniscal repair and factors that affect healing. Parameters of interest were type and location of the tear and also the influence of simultaneous reconstruction of a ruptured ACL.

Methods

We investigated the outcome of 25 patients (29 menisci) aged 15 (4–17) years who underwent surgery for full thickness meniscal tears, either as isolated lesions or in combination with ACL ruptures. Intraoperative documentation followed the IKDC 2000 standard. Outcome measurements were the Tegner score (pre- and postoperatively) and the Lysholm score (postoperatively) after an average follow-up period of 2.3 years, with postoperative arthroscopy and MRT in some cases.

Results

24 of the 29 meniscal lesions healed (defined as giving an asymptomatic patient) regardless of location or type. 4 patients re-ruptured their menisci (all in the pars intermedia) at an average of 15 months after surgery following a new injury. Mean Lysholm score at follow-up was 95, the Tegner score deteriorated, mean preoperative score: 7.8 (4–10); mean postoperative score: 7.2 (4–10). Patients with simultaneous ACL reconstruction had a better outcome.

Interpretation

All meniscal tears in the skeletally immature patient are amenable to repair. All recurrent meniscal tears in our patients were located in the pars intermedia; the poorer blood supply in this region may give a higher risk of re-rupture. Simultaneous ACL reconstruction appears to benefit the results of meniscal repair.Isolated meniscal tears in the skeletally immature patient are rare but well-recognized injuries (Hede et al. 1990). Meniscal tears are frequently seen in association with a ruptured ACL (Bellisari et al. 2011, Samora et al. 2011). The menisci reduce contact stress and buffer axial, rotational, and shearing forces, thereby protecting the articular cartilage (Kurosawa et al. 1980). In the classic paper by Fairbank (1948), early osteoarthritis was clearly shown to be the inevitable outcome of total medial menisectomy. This led to the development of various techniques of meniscal repair in order to improve long-term outcome. This is particularly desirable in the immature patient, as early degenerative changes in this population have profound consequences in the long term. There are a variety of all-inside arthroscopic techniques that are relatively easy to master and that can be quick to perform as compared to the more technically demanding inside-out and outside-in methods (Haas et al. 2005, Kotsovolos et al. 2006).The results of meniscal repair in adults have been reported to be fair to good (Barber 1987, Eggli et al. 1995), while there have been few published data for children and adolescents (Krych et al. 2008). In this retrospective study, we assessed the outcome in a cohort of children and adolescents undergoing meniscal repair and determined whether there was any relationship between the type of meniscal injury and the outcome.     

Application of a computerised navigation technique to assist arthroscopic anterior cruciate ligament reconstruction

Purpose

Based on biomechanical cadaver studies, anatomical double-bundle reconstruction of the anterior cruciate ligament (ACL) was introduced to achieve better stability in the knee, particularly in respect of rotatory loads. Previously, the success of ACL reconstruction was believed to be mainly dependent on correct positioning of the graft, irrespective of the number of bundles for which computer-assisted surgery was developed to avoid malpositioning of the tunnel. The aim of this study was to compare rotational and translational stability after computer-navigated standard single-bundle and anatomical double-bundle ACL reconstruction.

Methods

The authors investigated 42 consecutive patients who had undergone the single-bundle or double-bundle ACL reconstruction procedure using autogenous hamstring tendon grafts and ENDOBUTTON fixation in patients who had been followed up for a minimum of 24 months. Post-operative anteroposterior and rotational laxity was measured with the KT3000 and compared between groups.

Results

Both surgical procedures significantly improve rotational and translational stability compared to the preoperative ACL-deficient knee (P<0.05). No significant differences were registered between groups with regard to anteroposterior displacement of the tibia. The International Knee Documentation Committee (IKDC) and Lysholm scores were significantly higher in the double-bundle group. However, the results were excellent in both groups.

Conclusions

The use of computer-assisted ACL reconstruction, which is a highly accurate method of graft placement, could be useful for inexperienced surgeons to avoid malposition. Long-term results of at least five years are needed to determine whether double-bundle ACL reconstruction, which was associated with improved rotational laxity and significantly better IKDC and Lysholm scores compared to the standard single-bundle ACL reconstruction procedure, exerts an influence in terms of avoiding osteoarthritis or meniscus degeneration.     

Magnetic Resonance Imaging is not suitable for interpretation of meniscal status ten years after arthroscopic repair

Purpose

The purpose of this study was to assess the MRI features of the all-inside repaired meniscus in the long-term.

Methods

Among 27 consecutive all-inside arthroscopic meniscal repairs, 23 patients aged 25 ± 5 years at the time of surgery were reviewed at a median follow-up of 10 ± 1 years. Retrospective clinical examinations and imaging assessments using a 1.5-T MRI after all-inside arthroscopic meniscal repair were conducted.

Results

At follow-up, Lysholm and IKDC averaged 89 ± 11 and 95 ± 8, respectively. MRI examinations revealed no meniscal signal alteration in three patients (13 %), a vertical signal located in the previously torn area in seven (30 %), a horizontal grade 3 in nine (39 %), and a complex tear (grade 4) in four (17.5 %). There were no differences between medial and lateral menisci (p = 0.15), stable and stabilised knees (p = 0.56).

Conclusions

Several abnormal vertical and/or horizontal hypersignals are still present on MRI examination ten years after arthroscopic all-inside meniscal repair. The appearance of early signs of osteoarthritis is rare, suggesting a chondroprotective effect of the repaired meniscus.     

The Results of All-Inside Meniscus Repair Using the Viper Repair System Simultaneously with Anterior Cruciate Ligament Reconstruction

Background

Meniscus tears are commonly associated with anterior cruciate ligament (ACL) ruptures. It is essential to repair meniscal tears as much as possible to prevent early osteoarthritis and to gain additional stability in the knee joint. We evaluated the results of arthroscopic all-inside repair using the Meniscal Viper Repair System (Arthrex) on meniscus tears simultaneously with ACL reconstruction.

Methods

Nineteen out of 22 patients who were treated with arthroscopic all-inside repair using the Meniscal Viper Repair System for meniscus tear associated with ACL rupture were evaluated. ACL reconstructions were performed at the same period. The mean follow-up period was 16.5 months (range, 12 to 24 months). The clinical results of the meniscus repair were evaluated by symptoms (such as catching or locking), tenderness, effusion, range of motion limitation, and the McMurray test. Clinical success was defined by negative results in all five categories. The Hospital for Special Surgery (HSS) score was evaluated. Objective results were evaluated with secondary look arthroscopy or magnetic resonance imaging (MRI). The MRI results were categorized as completely repaired, incompletely repaired, and failure by Henning''s classification. The results of second-look arthroscopy were evaluated with the criteria of meniscal healing.

Results

The clinical success rate was 95.4% and the HSS scores were 93.9 ± 5.4 at the final follow-up. According to Henning''s classification, 15 out of 18 cases showed complete healing (83.3%) and two cases (11.1%) showed incomplete healing. Seventeen out of 18 cases that underwent second-look arthroscopy showed complete healing (94.4%) according to the criteria of meniscal healing. Only one case showed failure and the failure was due to a re-rupture at the sutured area. Complications of ACL reconstruction or meniscus repair were not present.

Conclusions

The results demonstrate that arthroscopic all-inside repair using the Meniscal Viper Repair System is an effective treatment method when it is performed simultaneously with ACL reconstruction.     

Clinical outcomes and complications of a collagen meniscus implant: a systematic review

Purpose

The purpose of this systematic review was to summarise and evaluate the clinical outcomes of the collagen meniscus implant (CMI) and its complication and failure rates. These data were then used to evaluate the results of the CMI at different follow-up time periods and investigate possible differences in the behaviour of lateral and medial CMI.

Methods

A comprehensive search was performed in PubMed, MEDLINE, CINAHL, Cochrane, EMBASE and Google Scholar databases using various combinations of the following keywords: “collagen meniscus implant” or “collagen meniscal implant”. All studies evaluating medial or lateral CMI using the Lysholm score, visual analogue scale (VAS) for pain, Tegner activity scale and subjective or objective International Knee Documentation Committee (IKDC) scores were included in the systematic review.

Results

Eleven studies were included in the systematic review. The pooled number of patients involved in CMI surgery were 396 (90.2 % medial, 9.8 % lateral), with a mean age at surgery of 37.8 years. Concomitant procedures were present in 48.8 % of patients; most of them were anterior cruciate ligament (ACL) reconstruction, high tibial osteotomy (HTO) and microfractures. The Lysholm score and VAS for pain showed an improvement at six months up to ten years. No noticeable differences were present comparing short-term values of Lysholm score between medial and lateral CMI. The Tegner activity level reached its peak at 12 months after surgery and showed a progressive decrease through five and ten years post CMI implantation, however always remaining above the pre-operative level. Only a few knees were rated as “nearly abnormal” or “abnormal” at IKDC grading at all follow-up evaluations.

Conclusions

The CMI could produce good and stable clinical results, particularly regarding knee function and pain, with low rates of complications and reoperations.     

Meniscal repair: indications and techniques

Meniscal tears are exceedingly common. Because the meniscus serves many vital functions to the knee joint, the preservation of meniscal tissue through meniscal repair is ideal. However, not all meniscal tears are amenable to repair, and each case must be critically assessed for repair suitability. It has been well documented that meniscal healing is enhanced in the setting of concurrent anterior cruciate ligament (ACL) reconstruction. This may influence the indications for repair, as well as the repair technique. Meniscal repair techniques have evolved over time from initial open repairs to inside-out and outside-in suture repairs to newer all-inside repair devices. The current gold standard remains inside-out vertical mattress suture repairs. All-inside repairs are best reserved for special circumstances, such as in the setting of concurrent ACL reconstruction.     

Examining Techniques for Treatment of Medial Meniscal Ramp Lesions During Anterior Cruciate Ligament Reconstruction: A Systematic Review

PurposeThe purpose of this study was to systematically review the clinical outcomes and adverse events among different techniques for treatment of medial meniscal ramp lesions performed in conjunction with anterior cruciate ligament (ACL) reconstruction.MethodsA systematic review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed, Cochrane Reviews, Web of Science, and Medline databases were searched for studies examining clinical outcomes after surgical treatment of ramp lesions. Studies were selected if they met the following criteria: (1) evaluation of the outcome of surgical repair of meniscal ramp lesions, (2) injuries associated with ACL tears, (3) minimum 6-month follow up, (4) publication in a peer-reviewed journal, and (5) English language or translation readily available.ResultsSeven studies met inclusion criteria (485 patients; mean age 27.1 years [range 12 to 59]; mean follow-up 26.9 months [range 8 to 40]). Two all-inside techniques (suture-hook and an all-inside meniscus repair device) in addition to abrasion and trephination alone were analyzed. Each technique demonstrated significant increases in postoperative Lysholm and International Knee Documentation Committee (IKDC) scores, reaching the established minimal clinically important difference (MCID) for each patient reported outcome. Incomplete healing was documented in 12.1% to 12.9% of cases in which the tear was not repaired at the time of ACL reconstruction, 2.3% to 11.7% in cases using the suture-hook for repair, and 10.8% to 15% in the all-inside meniscus repair device group.ConclusionThis systematic review demonstrated that several approaches used to treat medial meniscal ramp lesions associated with ACL tears lead to positive clinical outcomes. Small, stable tears <2 cm in size may be managed with debridement alone. For larger, more unstable lesions, an all-inside approach has demonstrated positive clinical outcomes. Prospective trials are needed to determine the best management for meniscal ramp lesions. Additionally, further research is needed to better understand how to minimize the risk of technique-related complications (e.g., improper implant deployment).Level of EvidenceLevel IV, systematic review of level II, III, and IV studies.     

Editorial Commentary: Combined Anterior Cruciate Ligament Reconstruction and Medial Meniscal Transplantation Improve Functional Outcomes When Properly Indicated

The anterior cruciate ligament (ACL) and medial meniscus both contribute to anteroposterior translation of the tibia. Biomechanical studies have found increased translation at both 30° and 90° when transecting the posterior horn of the medial meniscus, and clinically, medial meniscal deficiency has been shown to have a 46% increase in ACL graft strain at 90°. Medial meniscal deficiency is a risk factor for failure after ACL reconstruction, with a hazard ratio of 15.1. The combination of meniscal allograft transplantation and ACL reconstruction is technically demanding but results in mid- to long-term clinical improvement in well-indicated patients. Patients with medial meniscal deficiency and failed ACL reconstruction or with ACL deficiency and medial-sided knee pain due to meniscal deficiency are candidates for combined procedures. On the basis of our experience, acute meniscal injury is not an indication for primary meniscal transplantation in any setting. Surgeons should repair the meniscus if reparable or perform partial meniscectomy and see how the patient responds. There is insufficient evidence to show that early meniscal transplantation will be chondroprotective. We reserve this procedure for the indications previously described. Severe osteoarthritis (Kellgren-Lawrence grades III and IV) and Outerbridge grade IV focal chondral defects of the tibiofemoral compartment that are not amenable to cartilage repair are absolute contraindications to the combined procedure.     

Surgical timing of anterior cruciate ligament reconstruction to prevent associated meniscal and cartilage lesions

Background

The purpose of this study was to analyze the association between the prevalence of meniscal and chondral lesions and the timing of surgery in patients undergoing primary anterior cruciate ligament (ACL) reconstruction to determine a safe time for surgery.

Long-term results of anterior cruciate ligament reconstruction: a comparison with non-operative treatment with a follow-up of 17–20 years

Purpose

The aim of our study was to review the clinical and radiological outcome of patients who had undergone anterior cruciate ligament (ACL) reconstruction in comparison to a group of non-operatively treated patients.

Methods

In a retrospective study we compared ACL reconstruction using a bone-patellar tendon-bone graft with a non-operatively treated group of patients 17–20 years later. Fifty-four patients that met the inclusion criteria, with arthroscopically proven ACL rupture, were treated between 1989 and 1991. Thirty-three patients underwent ACL reconstruction, forming group one. Eighteen non-reconstructed patients continued with rehabilitation and modification of activities (group two). The International Knee Documentation Committee (IKDC) subjective and objective evaluation forms and the Lysholm and Tegner scale were used to assess the knees at follow-up. Radiographic assessment was performed using the IKDC grading scale.

Results

Follow-up results showed that 83% of reconstructed patients had stable knees and normal or nearly normal IKDC grade. Patients in the non-reconstructed group had unstable knees with 84% having abnormal or severe laxity. The subjective IKDC score was significantly in favour of group one: 83.15 compared to 64.6 in group two. The Lysholm and Tegner score was also significantly better in group one. Conservatively treated patients all had unstable knees and worse scores. The rate of osteoarthritis showed more severe changes in non-reconstructed patients with additional meniscus injury.

Conclusions

We can conclude that 94% of patients who underwent ACL reconstruction had stable knees after 15–20 years and there was a significantly lower percentage of osteoarthritis in comparison to conservatively treated patients.     

Usefulness of knee arthroscopy for diagnosis of knee pain in pediatric patients: comparison with preoperative clinical diagnosis

Purpose

To investigate the knee arthroscopic findings of pediatric patients with knee pain.

Subjects

Ninety-five knees of 94 patients (46 males and 48 females) aged 15 years or younger who underwent knee arthroscopy during a 4-year period from January 2007 were studied. The mean age at surgery was 13.5 (7–15) years. The mean interval from symptom onset to arthroscopic examination was 6.8 months (5 days to 2 years 10 months).

Results

The most common cause of knee pain was sports-related activities (64 knees). Other causes included falling from a moving bicycle (5 knees), while knee pain appeared with no defined reason in 14 knees. The most frequent final diagnosis based on knee arthroscopic findings was anterior cruciate ligament (ACL) injury (35 knees), followed by discoid lateral meniscus (16 knees), lateral meniscal tear (11 knees), and medial plica syndrome (9 knees), while no arthroscopic abnormality was observed in 8 of 95 knees. Among the 95 knees, the diagnosis based on preoperative physical tests and imaging findings was different from the arthroscopic diagnosis in 16 knees, 8 of which were diagnosed preoperatively as medial meniscal tear.

Conclusion

ACL injury and discoid lateral meniscus were the predominant conditions in pediatric patients who underwent knee arthroscopic surgery for knee pain. Knee arthroscopy is useful to provide a definitive diagnosis for knee pain in pediatric patients. Preoperative evaluations had a diagnostic accuracy of only 83.2 % and failed to diagnose conditions such as medial plica syndrome and chondral injury. Therefore, diagnosis before knee arthroscopy has to be interpreted with caution.     

Nonviral gene transfer to human meniscal cells. Part I: transfection analyses and cell transplantation to meniscus explants

Purpose

Our aim was to evaluate whether nonviral vectors can genetically modify primary human juvenile and adult meniscal fibrochondrocytes at low toxicity in vitro and to test the hypothesis that transfected human meniscal fibrochondrocytes transplanted into longitudinal defects and onto human medial meniscus explant cultures are capable of expressing transgene products in vitro.

Methods

Eighteen nonviral gene transfer systems were examined to identify the best suited method for an efficient transfection of primary cultures of juvenile and adult human meniscal fibrochondrocytes using luciferase and lacZ reporter gene constructs and then transplanted to meniscus explant cultures.

Results

Gene transfer systems FuGENE 6, GeneJammer, TurboFectin 8, calcium phosphate co-precipitates and GeneJuice led to minimal toxicity in both cell types. Nanofectin 2 and JetPEI resulted in maximal luciferase activity in both cell types. Maximal transfection efficiency based on X-gal staining following lacZ gene transfer was achieved using Lipofectamine 2000, revealing a mean transfection efficiency of 8.6 % in human juvenile and of 8.4 % in adult meniscal fibrochondrocytes. Transfected, transplanted meniscal fibrochondrocytes adhered to the meniscal tissue and continued to express the transgene for at least five days following transfection.

Conclusions

Nonviral gene transfer systems are safe and capable of transfecting both juvenile and adult human meniscal fibrochondrocytes, which, when transplanted to meniscal tissue in vitro, permit the expression of selected transgenes to be maintained. These results are of value for combining gene therapy and cell transplantation approaches as a means to enhance meniscal repair.     

Effects of different surgical procedures for meniscus injury on two-year clinical and radiological outcomes after anterior cruciate ligament reconstructions. -TMDU MAKS study

BackgroundThe treatment of meniscus injuries combined with anterior cruciate ligament (ACL) reconstruction would be important to improve outcomes after ACL reconstruction. However, the effects of treatment methods for meniscus after ACL reconstruction have not been thoroughly investigated. The objective of this study was to investigate the effects of treatment methods for meniscus on clinical and radiological outcomes at 2 years after ACL reconstruction.MethodsThree-hundred and eighteen patients with primary ACL reconstruction using autologous hamstring tendon registered in our multicenter study database and who were followed up for 2 years were included. They were then divided into 3 groups, the no meniscal lesion/untreated group (n = 149), the meniscal repair group (n = 139), and the meniscal resection group (n = 30). Patient-based subjective evaluations (Lysholm score, Knee injury and Osteoarthritis Outcome score and International Knee Documentation Committee subjective score), objective evaluations (Lachman test, pivot shift test and KT measurement), and radiological measurements (medial and lateral joint space width) were compared among the 3 groups preoperatively and at 2 years follow-up.ResultsAll subjective scores and objective evaluations significantly improved in all groups without significant differences among the groups postoperatively. Regarding radiological findings, the medial joint space width significantly decreased only in the resection group during the 2-year period, and the medial joint space width in the resection group was significantly smaller than that of the other groups at the 2-year follow-up. Moreover, the medial joint space width significantly decreased during the 2-year period when MM was resected.ConclusionsIn radiological findings, medial meniscus resection decreased medial joint space width two years after ACL reconstruction. On the other hand, treatment methods for meniscus neither significantly affected subjective nor objective findings until the 2-year follow-up.Level of evidenceⅡ, Cohort study.     

Clinical outcome and prevalence of osteoarthritis after isolated anterior cruciate ligament reconstruction using hamstring graft: follow-up after two and ten years

Purpose

The aim of this study was to evaluate patient-reported clinical outcome, instrumental stability and prevalence of radiological osteoarthritis (OA) based on a homogeneous patient sample after two years and on average ten years after isolated anterior cruciate ligament (ACL) reconstruction.

Methods

Primarily we performed ACL reconstruction using a four-strand semitendinosus tendon (ST) autograft in 112 patients. Two years after reconstruction 98 patients could be re-evaluated. Long-term clinical and functional follow-up assessment was then performed on 52 patients on average 10.2 years after operative treatment. Inclusion criteria consisted of an isolated ACL rupture, reconstruction with ST graft and no associated cartilage alterations and meniscal lesions. Clinical and functional follow-up assessment included the International Knee Documentation Committee (IKDC) score and the scores of Tegner and Lysholm. Instrumental stability testing was carried out with the KT1000? arthrometer. The degree of degenerative changes and prevalence of OA was based on the Jäger-Wirth score.

Results

The mean long-term follow-up was 10.2 years (eight–13 years), and the mean age was 40.4 years (24–62 years). About 72 % of patients were graded A or B according to the IKDC score. Activity levels according to the scores of Tegner and Lysholm were 4.8 and 88.2 on long-term follow-up. Radiological assessment revealed degenerative changes in the sense of a grade I OA in 21.2 % of patients. Prevalence of a grade II OA was found in 53.8 % of patients. A grade III OA and a grade IV OA were found in 19.2 and 5.7 %. Correlation analysis showed significant relationships between the long-term stability and prevalence of OA (p?<?0.05).

Conclusions

Arthroscopic ACL reconstruction using four-strand ST autograft resulted in high patient satisfaction and good clinical results at two years and long-term follow-up. The prevalence of higher degree OA that developed in about 25 % of patients is significantly correlated with long-term knee joint stability.     

The association between meniscal subluxation and cartilage degeneration

Purpose

The menisci play a critical protective role for the knee joint through shock absorption and load distribution. We hypothesized that cartilage degeneration will be abruptly progressed if meniscal subluxation exceeds a critical point.

Methods

Of 56 cases that showed medial meniscal subluxation without cartilage degeneration of ipsilateral medial femoral condyle (MFC) on initial MRI, from January 2005 to June 2007, meniscal subluxation index (MSI), the ratio of meniscal overhang to meniscal width in mid-coronal image of initial MRI, was measured. After 2 years, 40 cases were evaluated for cartilage degeneration of ipsilateral MFC on follow-up MRI. The relationship between medial MSI on initial MRI and cartilage degeneration of MFC on follow-up MRI was analyzed. Logistic regression analysis was conducted to find a critical point of meniscal subluxation related to cartilage degeneration.

Results

Abrupt progression of cartilage degeneration was observed from which MSI was 0.38. Logistic regression showed that if MSI was at the critical point, which was 0.38 in our study, then the probability of cartilage degeneration to grade 3 or 4 after 2 years was 44 %. If MSI was 0.4, then the probability was 50 %. If MSI was 0.6, then the probability was 99 %.

Conclusions

The results suggest the existence of critical point from which the protective function of the meniscus appears to be significantly altered, and the degree of cartilage degeneration of ipsilateral femoral condyle corresponding to the amount of medial meniscal subluxation may be predictable.