Meniscal repairs are commonly performed during anterior cruciate ligament (ACL) reconstruction. This study aimed to identify the risk factors for meniscal repair failure following concurrent primary ACL reconstruction. Primary ACL reconstructions with a concurrent repair of a meniscal tear recorded in the New Zealand ACL Registry between April 2014 and December 2018 were analyzed. Meniscal repair failure was defined as a patient who underwent subsequent meniscectomy, and was identified after cross-referencing data from the ACL Registry with the national database of the Accident Compensation Corporation (ACC). Multivariate Cox regression was performed to produce hazard ratios (HR) with 95% confidence intervals (CI) to identify the patient and surgical risk factors for meniscal repair failure. 2041 meniscal repairs were analyzed (medial = 1235 and lateral = 806). The overall failure rate was 9.4% (n = 192). Failure occurred in 11.1% of medial (137/1235) and 6.8% of lateral (55/806) meniscal repairs. The risk of medial failure was higher with hamstring tendon autografts (adjusted HR = 2.00, 95% CI 1.23 – 3.26, p = 0.006) and in patients with cartilage injury in the medial compartment (adjusted HR = 1.56, 95% CI 1.09 – 2.23, p = 0.015). The risk of lateral failure was higher when the procedure was performed by a surgeon with an annual case volume of less than 30 ACL reconstructions (adjusted HR = 1.92, 95% CI 1.10 – 3.33, p = 0.021). Age, gender, time from injury-to-surgery and femoral tunnel drilling technique did not influence the risk of meniscal repair failure. When repairing a meniscal tear during ACL reconstruction, the use of a hamstring tendon autograft or the presence of cartilage injury in the medial compartment increases the risk of medial meniscal repair failure. Lower surgeon case volume increases the risk of lateral meniscal repair failure

Background. Anterior cruciate ligament (ACL) reconstruction with concomitant meniscal injury occurs frequently. Meniscal repair is associated with improved long-term outcomes compared to resection but is also associated with a higher reoperation rate. Knowledge of the risk factors for repair failure may be important in optimizing patient outcomes. Purpose. This study aimed to identify the patient and surgical risk factors for meniscal repair failure, defined as a subsequent meniscectomy, following concurrent primary ACL reconstruction. Methods. Data recorded by the New Zealand ACL Registry and the Accident Compensation Corporation, the New Zealand Government's sole funder of ACL reconstructions and any subsequent surgery, was reviewed. Meniscal repairs performed with concurrent primary ACL reconstruction was included. Root repairs were excluded. Univariate and multivariate survival analysis was performed to identify the patient and surgical risk factors for meniscal repair failure. Results. Between 2014 and 2020, a total of 3,024 meniscal repairs were performed during concurrent primary ACL reconstruction (medial repair = 1,814 and lateral repair = 1,210). The overall failure rate was 6.6% (n = 201) at a mean follow-up of 2.9 years, with a failure occurring in 7.8% of medial meniscal repairs (142 out of 1,814) and 4.9% of lateral meniscal repairs (59 out of 1,210). The risk of medial failure was higher in patients with a hamstring tendon autograft (adjusted HR = 2.20, p = 0.001), patients aged 21–30 years (adjusted HR = 1.60, p = 0.037) and in those with cartilage injury in the medial compartment (adjusted HR = 1.75, p = 0.002). The risk of lateral failure was higher in patients aged ≤ 20 years (adjusted HR = 2.79, p = 0.021) and when the procedure was performed by a surgeon with an annual ACL reconstruction case volume of less than 30 (adjusted HR = 1.84, p = 0.026). Conclusion. When performing meniscal repair during a primary ACL reconstruction, the use of a hamstring tendon autograft, younger age and the presence of concomitant cartilage injury in the medial compartment increases the risk of medial meniscal repair failure, whereas younger age and low surgeon volume increases the risk of lateral meniscal repair failure

Meniscal tears are the most common knee injuries, occurring in acute ruptures or in chronic degenerative conditions. Meniscectomy and meniscal repair are two surgical treatment options. Meniscectomy is easier, faster, and the patient can return to their normal activities earlier. However, this procedure has long-term consequences in the development of degenerative changes in the knee, potentially leading to knee replacement. On the other hand, meniscal repair can offer prolonged benefits to the patients, but it is difficult to perform and requires longer rehabilitation. Sutures are used for meniscal repairs, but they have limitations. They induce tissue damage when passing through the meniscus. Furthermore, under dynamic loading of the knee, they can cause tissue shearing and potentially lead to meniscal repair failure. Our team has developed a new technology of resistant adhesive hydrogels to coat the suture used to repair meniscal tissue. The objective of this study is to biomechanically compare two suture types on bovine menisci specimens: 1) pristine sutures and 2) gel adhesive puncture sealing (GAPS) sutures, on a repaired radial tear under cyclic tensile testing. Five bovine knees were dissected to retrieve the menisci. On the 10 menisci, a complete radial tear was performed. They were separated in two groups and repaired using either pristine (2-0 Vicryl) or GAPS (2-0 Vicryl coated with adhesive hydrogels) with a single stitch and five knots. The repaired menisci were clamped on an Instron machine. The specimens were cyclically preconditioned between one and 10 newtons for 10 cycles and then cyclically loaded for 500 cycles between five and 25 newtons at a frequency of 0.16 Hz. The gap formed between the edges of the tear after 500 cycles was then measured using an electronic measurement device. The suture loop before and after testing was also measured to ensure that there was no suture elongation or loosening of the knot. The groups were compared statistically using Mann-Whitney tests for nonparametric data. The level of significance was set to 0.05. The mean gap formation of the pristine sutures was 5.61 mm (SD = 2.097) after 500 cycles of tensile testing and 2.38 mm (SD = 0.176) for the GAPS sutures. Comparing both groups, the gap formed with the coated sutures was significantly smaller (p = 0.009) than with pristine sutures. The length of the loop was equal before and after loading. Further investigation of tissue damage indicated that the gap was formed by suture filament cutting into the meniscal tissue. The long-term objective of this research is to design a meniscal repair toolbox from which the surgeon can adapt his procedure for each meniscal tear. This preliminary experimentation on bovine menisci is promising because the new GAPS sutures seem to keep the edges of the meniscal tear together better than pristine sutures, with hopes of a clinical correlation with enhanced meniscal healing

Meniscal tears are the most common knee injuries, occurring in acute ruptures or in chronic degenerative conditions. Meniscectomy and meniscal repair are two surgical treatment options. Meniscectomy is easier, faster, and the patient can return to their normal activities earlier. However, this procedure has long-term consequences in the development of degenerative changes in the knee, potentially leading to knee replacement. On the other hand, meniscal repair can offer prolonged benefits to the patients, but it is difficult to perform and requires longer rehabilitation. Sutures are used for meniscal repairs, but they have limitations. They induce tissue damage when passing through the meniscus. Furthermore, under dynamic loading of the knee, they can cause tissue shearing and potentially lead to meniscal repair failure. Our team has developed a new technology of resistant adhesive hydrogels to coat the suture used to repair meniscal tissue. The objective of this study is to biomechanically compare two suture types on bovine menisci specimens: 1) pristine sutures and 2) gel adhesive puncture sealing (GAPS) sutures, on a repaired radial tear under cyclic tensile testing. Five bovine knees were dissected to retrieve the menisci. On the 10 menisci, a complete radial tear was performed. They were separated in two groups and repaired using either pristine (2-0 Vicryl) or GAPS (2-0 Vicryl coated with adhesive hydrogels) with a single stitch and five knots. The repaired menisci were clamped on an Instron machine. The specimens were cyclically preconditioned between one and 10 newtons for 10 cycles and then cyclically loaded for 500 cycles between five and 25 newtons at a frequency of 0.16 Hz. The gap formed between the edges of the tear after 500 cycles was then measured using an electronic measurement device. The suture loop before and after testing was also measured to ensure that there was no suture elongation or loosening of the knot. The groups were compared statistically using Mann-Whitney tests for nonparametric data. The level of significance was set to 0.05. The mean gap formation of the pristine sutures was 5.61 mm (SD = 2.097) after 500 cycles of tensile testing and 2.38 mm (SD = 0.176) for the GAPS sutures. Comparing both groups, the gap formed with the coated sutures was significantly smaller (p = 0.009) than with pristine sutures. The length of the loop was equal before and after loading. Further investigation of tissue damage indicated that the gap was formed by suture filament cutting into the meniscal tissue. The long-term objective of this research is to design a meniscal repair toolbox from which the surgeon can adapt his procedure for each meniscal tear. This preliminary experimentation on bovine menisci is promising because the new GAPS sutures seem to keep the edges of the meniscal tear together better than pristine sutures, with hopes of a clinical correlation with enhanced meniscal healing

Anterior cruciate ligament (ACL) rupture with associated meniscal pathology commonly occurs in a young, active population. Preserving a greater proportion of the meniscus may improve long-term outcomes by maintaining shock absorption and knee stability. However, meniscal repair procedures involve longer healing and rehabilitation than meniscal debridement, which could affect return to work and activity. The purpose of this study was to examine the functional outcomes and quality of life scores through two years in patients undergoing ACL reconstruction (ACL-R) who had meniscal repair, meniscal debridement, or no meniscal damage at the time of reconstruction. Data for 1814 skeletally mature patients with isolated primary ACL-R was prospectively collected at a single centre from January 2010 to December 2015. Functional testing of operative to non-operative limb performance was completed at one- and two-years following surgery and included single-leg balance, single-leg hop for distance, timed six-meter hop, triple-hop for distance, and triple cross-over hop for distance. ACL-Quality-of-life questionnaires (ACL-QoL) were completed pre-operatively and at 1- and 2-years post-operatively. Descriptive statistics were completed for patient demographics and intra-operative pathology. Unpaired t-tests using 95% confidence intervals were conducted to compare groups. The patient cohort was 45% female, with a mean age of 31 years (SD 11, range 14–66). Meniscal injury was detected in 1229/1814 knees (67.8%). There were 729 debridements and 538 repairs performed. Graft choice was hamstring autograft in 85.8% of cases, bone-patellar-tendon-bone autograft in 2.5%, allograft in 10.1% and other graft types in 1.5%. Pre-operative ACL-QoL scores were 29 and 28.5 for knees without and with meniscal damage, respectively (p>0.05). Of 1814 patients, 1269 (69.9%) completed the ACL-QoL at the two-year appointment, and 1225 (67.5%) completed the functional testing. At two years post-operative, patients with no meniscal damage at surgery demonstrated superior limb symmetry performance on triple-hop for distance compared to patients with meniscal damage (98.4% vs 97.1%, p < 0 .05, CI 0.1–2.5%). No other functional testing parameters showed statistical significance. There was no difference in functional outcome between patients undergoing an isolated meniscal repair versus debridement at one- or two-years. ACL-QoL scores were statistically significantly higher at one- and two-years post-operative for patients without meniscal damage (1-year: 73 vs 70.2, p < 0 .05, CI 0.51–5.1, 2-years: 79.2 vs 76.1, p < 0 .05, CI 0.79–5.4). ACL-QoL scores were minimally higher for isolated meniscal debridement compared to isolated meniscal repair at both time points (1-year: 71.4 vs 68, p < 0 .05, CI 0.4–6.4, 2-years: 78.3 vs 74, p < 0 .05, CI 1.3–7.3). Functional outcomes do not differ at one or two years post-operatively for patients undergoing meniscal repair versus debridement concomitant with ACL-R. Quality of life scores were statistically significantly higher for the patients with no meniscal pathology at both one- and two-years post-operative. ACL-QoL scores were also statistically significantly different for the meniscal repair and debridement groups however these differences are unlikely to be clinically significant. Extended follow-up is needed to determine if the differences detected in ACL-QoL scores are sustained over time, as well as the long-term role of meniscal injury on functional outcomes

Aims. We studied the outcomes following arthroscopic primary repair of bucket handle meniscus tears to determine the incidence of re-tears and the functional outcomes of these patients. Methodology. Prospective cohort study. Over a 4-year period (2016 to 2020), 35 adult patients presented with a bucket handle tear of the meniscus. Arthroscopic meniscal repair was performed using either the all inside technique or a combination of all-inside and inside-out techniques. 15 patients also underwent simultaneous arthroscopic anterior cruciate ligament reconstruction. Functional knee scores were assessed using IKDC and Lysholm scores. Results. Mean patient age at surgery was 27 years (range, 17 to 53years). Medial meniscus was torn in 20 and lateral in 15 cases. Zone of tear was white on white in 19, red on white in 9 and red on red in 7 cases. Average delay from injury to surgery was 4 months. At a mean follow-up of 4.5 years, the meniscus repair failed in 3 patients (8.5 %). Outcome following re-tear was meniscus excision. Average IKDC scores in patients with intact repair were 74.04 against 56.67 in patients with a failed repair (p< 0.0001). Similarly, Lyshlom scores were 88.96 and 67.333, respectively (p<0.0001). Conclusion. The survivorship of primary repair of bucket handle meniscus tears in our series was 91.5% at medium term follow-up. Functional outcomes were significantly poor in patients with a failed repair compared to those with an intact repair

Background. A cell-based tissue-engineered construct can be employed for treating meniscal lesions occurring in the non-vascularized inner two-thirds. The objective of this study was to test the hypothesis that both pre-differentiation of human bone marrow derived stromal cells (hBMSCs) into chondrogenic lineage before cell seeding and platelet-rich plasma (PRP) pretreatment on a PLGA mesh scaffold enhances the healing capacity of the meniscus with hBMSCs-seeded scaffolds in vivo. Methods. PRP of 5 donors was mixed and used for the experiments. The woven PLGA mesh scaffold (VicrylTM, Ethicon) measuring 20×8 mm (thickness, 0.2 mm) was prepared. The scaffolds were immersed into 1,000 μl of PRP and were centrifuged at 150g for 10 min. Then, the scaffold was flipped 180° and the same procedure was done for the other side. After washing, the scaffolds were soaked into 1,000 μl of DMEM media. hBMSCs from an iliac crest of 10 patients after informed consent and approval of our IRB were induced into chondrogenic differentiation with chondrogenic media containing 10 ng/ml rhTGF-ß3 in 1.2% alginate bead culture system for 7 days. Then, 2×10. 5. hBMSCs were recovered, seeded onto the scaffold, and cultured under dynamic condition. Based on the presence of pre-differentiation into chondrogenic lineage and the PRP pretreatment, 4 study groups were prepared. (no differentiation without PRP, no differentiation with PRP, chondrogenic differentiation without PRP, chondrogenic differentiation with PRP) Cell number for each cell-seeded scaffold was determined at 24 hours after seeding. Then, scaffolds were placed between human meniscal discs and were implanted subcutaneously in nude mice for 6 weeks (n=10 per group). Results. Cell attachment analysis revealed no significant difference among groups (p>0.05). The average cell number attached on the scaffold was ranged 1.1×10. 5. to 1.2×10. 5. among groups after 24 hours, so the initial cell seeding efficiency was ranged 55 to 60%. Histologic results from the 10 constructs containing hBMSCs undifferentiated and seeded onto non-PRP treated scaffolds revealed none had healed at all. Of the constructs containing hBMSCs undifferentiated and seeded onto PRP-pretreated scaffolds, three menisci healed and seven did not heal. Of the constructs containing hBMSCs pre-differentiated into chondrogenic lineage and seeded onto non-PRP treated scaffolds, six menisci healed and four did not heal. Of the constructs containing hBMSCs pre-differentiated into chondrogenic lineage and seeded onto PRP-pretreated scaffolds, seven menisci healed and three did not heal. Histological evaluation demonstrated a continuous hypercellular new fibrous tissue integrating into the native devitalized meniscus disc tissue in healed samples. The histological outcome between the groups was significant (p<0.05) (Table 1) (Figure 1). Conclusion. hBMSCs, which were differentiated into chondrogenic lineage before cell seeding and attached PRP-pretreated PLGA mesh scaffolds, demonstrated enhanced healing capacity of human meniscus in a meniscal repair mouse model. These findings demonstrate that both pre-differentiation of hBMSCs into chondogenesis and the PLGA scaffold modified by PRP pretreatment provides more biomimetic and biocompatible strategy for cell-mediated meniscal repair. Acknowledgements. This study was supported by Basic Science Research Program through the National Research Foundation of Korea (#2015-01004099)

Introduction. Motion analysis is a validated method of assessing technical dexterity within surgical skills centers. A more accessible and cost-effective method of skills assessment is to use a global rating scale (GRS). We aimed to perform a validation experiment to compare an arthroscopic GRS against motion analysis for monitoring orthopaedic trainees learning simulated arthroscopic meniscal repairs. Methods. An arthroscopic meniscal repair task on a knee simulator was set up in a bioskills laboratory. Nineteen orthopaedic trainees with no experience of meniscal repair were recruited and their performance assessed whilst undertaking a standardized meniscal repair on 12 occasions. An arthroscopic GRS, assessing parameters such as “depth perception,” “bimanual dexterity,” “instrument handling,” and “final product analysis” was used to evaluate technical skill. Performance was assessed blindly by watching video recordings of the arthroscopic tasks. Dexterity analysis was performed using a motion analysis tracking system which measured “time taken,” “total path length of the subject's hands,” and “number of hand movements”. Results. Motion analysis objectively defined the learning curves and demonstrated significant improvement in performance over the 12 tasks (p< 0.0001). The GRS demonstrated the same learning curve with a significant improvement in performance (p< 0.0001). Importantly, for each individual subject, there was significant improvement in performance as assessed by GRS over the 12 tasks (p< 0.0001). There was a moderate correlation (p< 0.0001) between GRS and all the motion analysis parameters (r values: time=−0.58, path length=−0.58, hand movements=−0.51). Conclusion. Established arthroscopic GRSs have not previously been used to monitor learning curves during complex arthroscopic tasks. The results demonstrate that both the GRS and motion analysis are able to detect performance improvement during such tasks. This further validates the arthroscopic GRS for use in monitoring individual trainees and has the advantage over motion analysis of being directly transferrable to the operating room

Background. The meniscal deficient knee often exists in the setting of associated pathology including instability, malalignment and chondral injury. Meniscal allograft transplantation (MAT) is established to be a reliable option in restoring function and treating symptoms. The aim of this study was to establish the role of MAT as part of a staged approach to treatment of the previously menisectomised knee. Methods. This prospective study included all patients that underwent arthroscopic MAT at our institution between 2010 to 2017. Fresh frozen allograft was utilised using a soft tissue fixation technique. Further data was collected for index surgical procedures before and after MAT. Data for pre and post-operative Knee Injury and osteoarthritis outcome scores (KOOS), Tegner scores, graft survival, reoperation rates, patient satisfaction and MRI extrusion measurements were collected and details of any further surgical intervention and / or complications also documented. Results. Twenty seven MAT procedures were performed in 26 patients. Sixteen patients underwent lateral MAT and 11 patients medial. Ten patients underwent ACL reconstruction, three ACI and two, osteotomy in the pre-MAT phase. A further seven patients underwent ACI within the post-operative phase. The post-operative mean KOOS scores improved significantly in all subscales as did Tegner scores. Graft survival was 100%, satisfaction rate 92%, and mean meniscal extrusion 3.04mm. Post operatively, three patients required meniscal repair and a single patient partial menisectomy of graft. Two patients underwent arthroscopic arthrolysis following MAT. Conclusions. This series highlights the multifactorial profile of the meniscal deficient knee and the role of MAT as a safe and reliable technique in the staged and comprehensive biologic treatment available to minimise symptoms and maximise outcomes

The absence of menisci in the knee leads to early degenerative changes. Complete radial tears of the meniscus are equivalent to total meniscectomy and repair should be performed if possible. The purpose of this study was to biomechanically compare the cross suture, hashtag and crosstag meniscal repairs using all-inside implants for radial tears. Radial tears were created at the mid-body of 36 fresh-frozen lateral human menisci and then repaired, in randomiSed order, with Fast-Fix™ 360s (Smith & Nephew, Andover, MA) using the cross suture, hashtag and crosstag techniques. The repaired menisci were tested using an Instron Electropuls E10000 (Instron, Norwood, MA). The tests consisted of cyclic loading from 5 to 30N at 1Hz for 500 cycles, then a load to failure test. Displacement following cyclic loading, load at 3mm of displacement, load to failure, and stiffness were recorded. Any differences between repairs were assessed using Kruskal-Wallis and Mann Whitney tests (p<0.05). Cross suture repairs displaced more following cyclic loading and resisted less load to failure than both the hashtag and crosstag repairs. However, these differences were not statistically significant. The average displacement following cyclic loading of cross suture, hashtag, and crosstag repairs was 4.34 mm (±2.02 mm), 3.46 mm (±2.12 mm), and 3.24 mm (±1.52 mm) respectively (p=0.33). Maximal load to failure was 64.83 N (±17.41 N), 74.52 N (±9.03 N), and 74.98N (±10.50N), respectively (p=0.419). All-inside cross suture, hashtag and crosstag repairs all displaced >3mm with cyclic loading, which is the threshold for meniscal insufficiency. This contrasts previous studies using inside-out sutures, where crosstag and hashtag repairs resisted cyclic loading (< 3mm). Inside-out suturing for radial tears of the lateral meniscus currently remains the gold standard

Purpose. To evaluate the results of quadrupled hamstring tendon autograft anterior cruciate ligament reconstruction with four fold Hamstring Tendon Graft using Transfix and Bioabsorbable Interference Screw Fixation. Study Design. Retrospective review. Methods. Sixty-five patients (66 knees) were retrospectively identified by chart review as having undergone quadrupled hamstring tendon autograft anterior cruciate ligament reconstruction, with four fold Hamstring Tendon Graft, using Transfix and Bioabsorbable Interference Screw Fixation. All patients underwent a minimum two-year follow-up. Results. Data were collected on 48 knees in 47 patients (73%) at an average 30.2 months (range 24 to 43) after surgery. Thirty-six patients (37 knees) returned for clinical evaluation (56% return) and subjective follow-up only was obtained in 11 patients (17%). The mean Lysolm knee score was 91 (range, 45 to 98), with a mean of 97 for the uninvolved knee. The mean Tegner activity score was 5.7 (range 3 to 7). The KT-1000 arthrometer mean side-to-side difference for manual maximum displacement was 2.03 mm (range -1 to 8). The mean International Knee Documentation Committee knee score was 83 (range 47 to 100). Patients who underwent associated partial meniscectomy or meniscal repair had significantly lower International Knee Documentation Committee scores than patients without associated procedures (P < 0.01). Conclusions. Quadrupled hamstring tendon autograft anterior cruciate ligament reconstruction with bioabsorbable interference screw fixation is comparable with other methods of anterior cruciate ligament reconstruction in terms of patient satisfaction, knee stability, and function

An ACL reconstruction is designed to restore the normal knee function and prevent the onset and progression of degenerative changes such as osteoarthritis. However, contemporary literature provides limited consensus on whether knee degeneration can be attenuated by the reconstruction procedure. The aim of this pilot study was to identify the presence of early osteoarthritis after ACL reconstruction using MRI analysis. 19 patients who had undergone an ACL reconstruction (9 isolated ACL rupture, 8 ACL rupture and meniscectomy, 2 ACL rupture and meniscal repair) volunteered for this study. MRI's were collected preoperatively and postoperatively for analysis with a mean follow up of 23 months. The Boston-Leeds Osteoarthritis Knee Score (BLOKS) was used for the analysis of the articular cartilage by a consultant orthopaedic surgeon. Scores ranged from 0–3, with 0 being total coverage and thickness of the cartilage and 3 being no coverage. Qualitative analysis was then conducted on each patient to determine if the articular cartilage improved, degenerated, or did not change between preoperative and follow-up scans. All patients with isolated ACL rupture were found to either have no change or improved articular cartilage scores in their follow up scans compared preoperatively. In contrast, patients with a meniscal repair displayed worse cartilage scores postoperatively. Lastly, of the patients who had an associated meniscectomy, 6 had worse follow-up results, with the remaining patients showing no change or improved cartilage scores. The present results indicate that patients with an isolated ACL rupture have a reduced risk of developing OA compared to those with associated meniscal injuries. This has implications for analysing the outcome of current ACL reconstruction techniques and in predicting the likelihood of patients developing OA after ACL reconstruction. Future work will involve confirming this pattern in a larger patient sample, as well as exploring additional factors such as time to surgery delay and rehabilitation strategy

Purpose. Factors that contribute to early and late re-operation after cruciate reconstruction (CR) have not been evaluated on a population level in a public health system. After surgery patients are at risk for knee stiffness, infection or early graft failure prompting revision. Long-term, ipsilateral revision CR, contralateral CR and potentially even joint replacement may occur. Population research in total joint replacement surgery has demonstrated an inverse relationship between complication/failure rates and surgeon procedural volume. We hypothesized that in Ontario, younger patient age and lower surgeon volume would increase the risk of short and long-term re-operation after CR. Method. Billing, procedural and diagnostic coding from administrative databases (Ontario Health Insurance Plan, Canadian Institutes of Health Research) were accessed through the Institute for Clinical Evaluative Sciences to develop the cohort of all Ontario residents aged 14 to 60 who underwent anterior or posterior CR from July 1992 to April 2008. Logistic regression analysis was used to calculate the odds ratio for patient (age, gender, comorbidity, income, concurrent knee surgery) and provider (surgeon volume, teaching hospital status) factors for having a surgical washout of the knee, manipulation for stiffness or repeat of the index event within six months. A cox proportional hazards survivorship model was used to calculate the hazard ratio of the same covariates for repeat CR and partial/total knee arthroplasty from inception until end of 2009. Results. The cohort identified 34,735 CR patients with a median age 28 yrs (IQR 20–36) and 65% male. Re-operation for infection was 0.2% and stiffness 0.5%. The long-term rate of any repeat CR was 7.7% after a mean 4.23.4 years. Female gender (OR=2.8, p<0.0001), overnight hospital stay (OR=2.1, p=0.0005), meniscal repair with CR (OR=1.9, p=0.008) and surgeon volume of 0–12 CR/yr (OR=4.0, p=0.0006), significantly increased the odds of re-operation for stiffness. The odds of re-operation for infection were significantly increased for surgeons performing 0–12 CR/yr (OR=3.8, p=0.007), and for CR performed at a teaching hospital (OR=2.3, p=0.002). Repeat CR was not influenced by surgeon volume at any time-point. Survival analysis demonstrated a long-term repeat CR rate of 13% (HR=1.8, p<0.0001) for age 14–19 yrs compared to the mean cohort age. Late partial or total knee replacement occurred in 0.75% of patients, with increased risk found for patients >30 years (HR=2.5, p=0.002), or who had concurrent surgery for an osteochondral lesion at the index CR (HR=2.3, p=0.001). Conclusion. Although this data is limited by the ability to distinguish between anterior or posterior and revision or contralateral CR, we have demonstrated that lower volume surgeons have higher complication rates (stiffness, infection) after CR surgery. We have also identified at-risk groups, such as females for stiffness post-CR and osteochondral injury + CR for eventual knee replacement