Citations

Background: Nonoperative and operative management techniques after anterior cruciate ligament (ACL) injury are both appropriate treatment options for selected patients. However, the subsequent development of posttraumatic knee osteoarthritis (PTOA) remains an area of active study. Purpose: To compare the risk of PTOA between patients treated without surgery and with ACL reconstruction (ACLR) after primary ACL disruption using a machine learning causal inference model. Study Design: Cohort study; Level of evidence, 3. Methods: A geographic database identified patients undergoing ACLR between 1990 and 2016 with minimum 7.5-year follow-up. Variables collected include age, sex, body mass index, activity level, occupation, relevant comorbid diagnoses, radiographic findings, injury characteristics, and clinical course. Treatment effects of ACLR on the development of PTOA and progression to total knee arthroplasty (TKA) were analyzed with machine learning models (MLMs) in a causal inference estimator (targeted maximum likelihood estimation, TMLE), while controlling for confounders. Results: The study included 1194 patients with a minimum follow-up of 7.5 years, among whom 974 underwent primary reconstruction and 220 underwent nonoperative treatment. A total of 215 (22%) patients developed symptomatic PTOA in the ACLR group compared with 140 (64%) in the nonoperative treatment group ( P < .001), whereas 25 (3%) patients underwent TKA in the ACLR group compared with 50 (23%) in the nonoperative treatment group ( P < .001). Patients in the ACLR group had delayed TKA compared with patients in the nonoperative treatment group (193.4 vs 166.0 months, respectively; P = .02). TMLE evaluation revealed that reconstruction decreased the risk of PTOA by 11% (95% CI, 8%-13%; P < .001) compared with nonoperative treatment but did not demonstrate a significant effect on the rate of progression to TKA. Survival analysis with random forest algorithm demonstrated significant delay to the onset of PTOA as well as time to progression of TKA in patients undergoing ACLR. Additional risk factors for the development of PTOA, irrespective of treatment, included older age at injury, greater body mass index, total number of arthroscopic knee surgeries, and residual laxity at follow-up. Conclusion: MLMs in a causal inference estimator found ACLR to exert a significant treatment effect in reducing the rate of development of PTOA by 11% compared with nonoperative treatment. ACLR also delayed the onset of PTOA and progression to TKA.

Background: Bucket-handle meniscal tears (BHMTs) are a common subtype of meniscal tears that represent a clinical challenge. Arthroscopic inside-out repair has been considered the gold standard in treatment; however, an all-inside approach has gained widespread popularity, with limited long-term evidence. Purpose/Hypothesis: The purpose of this study was to (1) compare long-term clinical outcomes and rates of failure after surgical repair of BHMTs using the all-inside versus inside-out technique, and 2) identify risk factors for failure at long-term follow-up. It was hypothesized that clinical outcomes and rates of failure would be similar between the 2 techniques. Study Design: Cohort study; Level of evidence, 3. Methods: Patients who had undergone surgical repair of BHMTs between 2003 and 2013 at a single institution were identified. Patient-reported outcome measures (PROMs) were assessed preoperatively and at the latest follow-up using the Tegner scale, International Knee Documentation Committee questionnaire, and visual analog scale pain at rest and with activity. A univariate Cox proportional hazards model was used to identify predictors for repair failure, defined as revision meniscal surgery and/or documented meniscal retear. Results: In total, 63 patients were included (37 with inside-out repair, 26 with all-inside repair). At a mean follow-up of 11.2 years, the survival rate for BHMT repair was 63% overall, 70% for all-inside repairs, and 60% for inside-out repairs ( P = .37). The mean time to failure was 2.6 years for all-inside repairs and 2.5 years for inside-out repairs ( P = .98). PROM scores were not significantly different between the 2 repair groups ( P > .22). Univariate Cox proportional hazards model for failure demonstrated that increasing age at surgery was associated with lower failure rates (hazard ratio, 0.91 change per 1-year increase in age; 95% CI, 0.84-0.98) and medial meniscus repair was associated with higher failure rates (hazard ratio, 3.12; 95% CI, 1.14-8.77). Conclusion: Long-term follow-up of BHMT repair demonstrated satisfactory clinical outcomes and failure rates. In appropriately selected patients, the all-inside technique did not compromise outcome as compared with the inside-out repair techniques. For both methods, older age was associated with lower failure rates and medial meniscus repair was associated with increased failure.

Background: As machine learning becomes increasingly utilized in orthopaedic clinical research, the application of machine learning methodology to cohort data from the Multicenter ACL Revision Study (MARS) presents a valuable opportunity to translate data into patient-specific insights. Purpose: To apply novel machine learning methodology to MARS cohort data to determine a predictive model of revision anterior cruciate ligament reconstruction (rACLR) graft failure and features most predictive of failure. Study Design: Cohort study; Level of evidence, 3. Methods: The authors prospectively recruited patients undergoing rACLR from the MARS cohort and obtained preoperative radiographs, surgeon-reported intraoperative findings, and 2- and 6-year follow-up data on patient-reported outcomes, additional surgeries, and graft failure. Machine learning models including logistic regression (LR), XGBoost, gradient boosting (GB), random forest (RF), and a validated ensemble algorithm (AutoPrognosis) were built to predict graft failure by 6 years postoperatively. Validated performance metrics and feature importance measures were used to evaluate model performance. Results: The cohort included 960 patients who completed 6-year follow-up, with 5.7% (n = 55) experiencing graft failure. AutoPrognosis demonstrated the highest discriminative power (model area under the receiver operating characteristic curve: AutoPrognosis, 0.703; RF, 0.618; GB, 0.660; XGBoost, 0.680; LR, 0.592), with well-calibrated scores (model Brier score: AutoPrognosis, 0.053; RF, 0.054; GB, 0.057; XGBoost, 0.058; LR, 0.111). The most important features for AutoPrognosis model performance were prior compromised femoral and tibial tunnels (placement and size) and allograft graft type used in current rACLR. Conclusion: The present study demonstrated the ability of the novel AutoPrognosis machine learning model to best predict the risk of graft failure in patients undergoing rACLR at 6 years postoperatively with moderate predictive ability. Femoral and tibial tunnel size and position in prior ACLR and allograft use in current rACLR were all risk factors for rACLR failure in the context of the AutoPrognosis model. This study describes a unique model that can be externally validated with larger data sets and contribute toward the creation of a robust rACLR bedside risk calculator in future studies. Registration: NCT00625885 (ClinicalTrials.gov identifier).

Background: Second-generation highly cross-linked polyethylene (HXLPE) has revolutionized total hip arthroplasty. However, the long-term risks and benefits of HXLPE in primary total knee arthroplasty (TKA) remain unknown. This randomized clinical trial evaluated implant survivorship, complications, radiographic results, and clinical outcomes of HXLPE and conventional ultra-high molecular weight polyethylene (UHMWPE) inserts in primary TKAs. Methods: We enrolled 518 patients (518 knees) who underwent primary TKA in 3 centers within 1 tertiary referral network. The mean age was 67 years, the mean body mass index was 32 kg/m 2 , and 58% of the patients were women. All of the patients underwent primary TKA with a cemented posterior-stabilized tibial insert and patellar resurfacing. Randomization proceeded via stratified dynamic allocation. The patients were blinded to their study group allocation: those in the control group (254 knees) underwent TKA with an UHMWPE insert (N2Vac; Stryker); those in the treatment group (264 knees) received an HXLPE insert (X3; Stryker). Kaplan-Meier survivorship, radiographic results, and clinical outcomes were assessed. This trial was registered with ClinicalTrials.gov. The mean follow-up was 11 years. Results: The 10-year overall survivorship free from any revision and from any reoperation was 96% and 94%, respectively. There were no differences in the risk of revision or reoperation between the groups (p > 0.05). There were a total of 19 revisions. Revision indications included periprosthetic joint infection (14 knees), instability (4 knees), and open reduction and internal fixation (ORIF) for a patellar fracture due to osteolysis around a UHMWPE insert (1 knee). There were no revisions due to polyethylene wear, osteolysis, or fracture of the post in the HXLPE group. The radiographic results and clinical outcomes were otherwise similar. Conclusions: Notably, no wear-related failures were identified in the HXLPE group, but there was 1 case of osteolysis in the UHMWPE group. Level of Evidence: Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

Background: Revision anterior cruciate ligament (ACL) reconstruction has been documented to have inferior outcomes compared with primary ACL reconstruction. The reasons why remain unknown. Purpose: To determine whether surgical factors performed at the time of revision ACL reconstruction can influence a patient’s outcome at 6-year follow-up. Study Design: Cohort study; Level of evidence, 2. Methods: Patients who underwent revision ACL reconstruction were identified and prospectively enrolled between 2006 and 2011. Data collected included baseline patient characteristics, surgical technique and pathology, and a series of validated patient-reported outcome instruments: Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) subjective form, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Marx activity rating score. Patients were followed up for 6 years and asked to complete the identical set of outcome instruments. Regression analysis was used to control for baseline patient characteristics and surgical variables to assess the surgical risk factors for clinical outcomes 6 years after surgery. Results: A total of 1234 patients were enrolled (716 men, 58%; median age, 26 years), and 6-year follow-up was obtained on 79% of patients (980/1234). Using an interference screw for femoral fixation compared with a cross-pin resulted in significantly better outcomes in 6-year IKDC scores (odds ratio [OR], 2.2; 95% CI, 1.2-3.9; P = .008) and KOOS sports/recreation and quality of life subscale scores (OR range, 2.2-2.7; 95% CI, 1.2-4.8; P < .01). Use of an interference screw compared with a cross-pin resulted in a 2.6 times less likely chance of having a subsequent surgery within 6 years. Use of an interference screw for tibial fixation compared with any combination of tibial fixation techniques resulted in significantly improved scores for IKDC (OR, 1.96; 95% CI, 1.3-2.9; P = .001); KOOS pain, activities of daily living, and sports/recreation subscales (OR range, 1.5-1.6; 95% CI, 1.0-2.4; P < .05); and WOMAC pain and activities of daily living subscales (OR range, 1.5-1.8; 95% CI, 1.0-2.7; P < .05). Use of a transtibial surgical approach compared with an anteromedial portal approach resulted in significantly improved KOOS pain and quality of life subscale scores at 6 years (OR, 1.5; 95% CI, 1.02-2.2; P≤ .04). Conclusion: There are surgical variables at the time of ACL revision that can modify clinical outcomes at 6 years. Opting for a transtibial surgical approach and choosing an interference screw for femoral and tibial fixation improved patients’ odds of having a significantly better 6-year clinical outcome in this cohort.

Background Advanced neuromuscular training prepares patients with anterior cruciate ligament reconstruction (ACLR) for sport participation. Return-to-sport testing often includes single-leg hop tests, yet combining motor and cognitive tasks (i.e., dual-task) might reveal neurocognitive reliance. Purpose/Hypothesis This study examined changes in performance on visuomotor reactions tests and single-leg hop tests following advanced neuromuscular training in patients with ACLR. The hypothesis was that performance would improve less on reaction tests than on single-leg hop tests. Study Design Quasi experimental, Pretest-Posttest Methods Twenty-five patients with ACLR (11 males) completed 10 sessions of advanced neuromuscular training and pre-and post-training testing. Reaction tests outcomes were from a platform and visual display. The double-leg reaction test involved touching target dots with either leg for 20 seconds; correct touches and errors were recorded. The single-leg reaction test involved hopping on the test leg to 10 target dots; hop time and errors were recorded. Single-leg hop tests included forward, triple, crossover triple, and timed hop; limb symmetry index was recorded. Effect sizes were calculated for corrected touches on the double-leg reaction test, surgical side hop time on the single-leg reaction test, and surgical side hop distance or time on single-leg hop tests. Results Correct touches on the double-leg reaction test significantly increased from pre- to post-training (20.4 +/- 4.3 vs. 23.9 +/- 2.8, p<0.001). Hop time on the single-leg reaction test significantly decreased from pre- to post-training (Surgical leg 13.2 vs. 12.3 seconds, non-surgical leg 13.0 vs. 12.1 seconds, p=0.003). Mean errors did not significantly change on either reaction test (p> 0.05). Cohens d effect sizes in descending order was single-leg hop tests (d=0.9 to 1.3), double-leg reaction test (d=0.9), and single-leg reaction test (d=0.5). Conclusion Motor performance improved after advanced neuromuscular training, but the effect size was less on visuomotor reaction tests than single-leg hop tests. The results suggest persistence of neurocognitive reliance after ACLR and a need for more dual-task challenges in training. Level of Evidence 3

Objectives: Ice hockey is a physically demanding sport, with young athletes prone to anterior cruciate ligament (ACL) injuries. Currently, there is a paucity of data examining the results of ACL reconstruction (ACLR) in competitive hockey players. The purpose of this study was to assess return to hockey (RTH) and reoperation rates following ACLR for ACL injuries in a cohort of competitive hockey players. Methods: All competitive ice hockey players (including, youth, high school, juniors, collegiate, or professional) with a history of ACL injury and subsequent ACLR at a single academic institution between 2000 and 2022 were identified. Exclusion criteria included ACL injuries that did not occur during hockey, history of ACLR prior to hockey injury, and recreational hockey players. Graft failure was defined as a retear (as determined via clinical or advanced imaging evaluation) and/or revision ACLR. Results: Ultimately, 50 knees in 44 hockey players were included at a mean (± standard deviation) follow-up time of 7.0 years ± 5.4 years (Table 1). The mean age at the time of index surgery was 18.9 years ± 3.0 years, with 38 males (76%), and the distribution of bone-patellar tendon-bone (BPTB) and hamstring tendon (HT) autografts was 40 (80%) and 10 (20%), respectively. RTH occurred in 66% of hockey players at a mean of 10.2 months ± 6.2 months. Graft failure occurred in 9 knees (18%) at a mean of 5.9 years ± 5.8 years after the index ACLR. All patients who sustained a retear underwent reoperation. Kaplan-Meier survivorship free from surgical failure of the entire cohort was 94% at 1 year, 88% at 5 years, 74% at 10 years, and 67% at 15 years (Figure 1A). BPTB autograft demonstrated a lower failure rate compared with HT autograft (13% vs 40%; P = 0.041) and was associated with better survival compared with HT autograft up to 15 years after the index ACLR (80% vs 39%; P = 0.047; Figure 1B). Conclusions: ACL injury remains a concern for competitive hockey players after ACLR. Return to competitive ice hockey was observed in 66% of athletes after ACLR, with 18% of hockey players experiencing graft failure and undergoing subsequent reoperation. BPTB autograft was associated with better survival than HT autograft.

Multiligament knee injuries (MLKIs) represent a broad spectrum of pathology with potentially devastating consequences. Currently, disagreement in the terminology, diagnosis and treatment of these injuries limits clinical care and research. This study aimed to develop consensus on the nomenclature, diagnosis, treatment and rehabilitation strategies for patients with MLKI, while identifying important research priorities for further study. An international consensus process was conducted using validated Delphi methodology in line with British Journal of Sports Medicine guidelines. A multidisciplinary panel of 39 members from 14 countries, completed 3 rounds of online surveys exploring aspects of nomenclature, diagnosis, treatment, rehabilitation and future research priorities. Levels of agreement (LoA) with each statement were rated anonymously on a 5-point Likert scale, with experts encouraged to suggest modifications or additional statements. LoA for consensus in the final round were defined ‘a priori’ if >75% of respondents agreed and fewer than 10% disagreed, and dissenting viewpoints were recorded and discussed. After three Delphi rounds, 50 items (92.6%) reached consensus. Key statements that reached consensus within nomenclature included a clear definition for MLKI (LoA 97.4%) and the need for an updated MLKI classification system that classifies injury mechanism, extent of non-ligamentous structures injured and the presence or absence of dislocation. Within diagnosis, consensus was reached that there should be a low threshold for assessment with CT angiography for MLKI within a high-energy context and for certain injury patterns including bicruciate and PLC injuries (LoA 89.7%). The value of stress radiography or intraoperative fluoroscopy also reached consensus (LoA 89.7%). Within treatment, it was generally agreed that existing literature generally favours operative management of MLKI, particularly for young patients (LoA 100%), and that single-stage surgery should be performed whenever possible (LoA 92.3%). This consensus statement will facilitate clinical communication in MLKI, the care of these patients and future research within MLKI.

Background: Previous studies have demonstrated that medial meniscus posterior root tear (MMPRT) repair is superior to debridement in terms of patient-reported outcomes, rates of conversion to total knee arthroplasty (TKA), and long-term costs. Despite the known poor midterm outcomes, there is a paucity of long-term results of partial meniscectomy for degenerative MMPRTs. Purpose: To 1) evaluate long-term patient-reported and radiographic outcomes of patients who underwent partial medial meniscectomy (PMM) for MMPRTs, and 2) determine the rate of and risk factors for conversion to total knee TKA. Study Design: Case series; Level of evidence, 4. Methods: A previously identified cohort of 26 patients treated with partial meniscectomy for isolated MMPRTs between 2005 and 2013 was prospectively followed for long-term outcomes at a minimum 10-year follow-up. Patients were evaluated for International Knee Documentation Committee (IKDC) outcome score, reoperation, and conversion to TKA. Failure was defined as conversion to arthroplasty or a severely abnormal IKDC subjective score <75.4. Results: This study included 26 patients (10 men, 16 women; mean age, 54 ± 8.7 years [range, 38-71 years] at diagnosis; body mass index, 32.9 ± 5.5) who were followed for a mean of 14.0 ± 3.6 years (range, 10.1-19.6 years). At the final follow-up, 1 patient was deceased and 18 (72%) of the remaining 25 patients had progressed to TKA, with 1 (4%) patient undergoing repeat meniscectomy. The 6 (24%) patients who had not progressed to TKA or revision surgery reported a mean IKDC score of 57 ± 23. Nineteen patients underwent subsequent surgery and 5 demonstrated severely abnormal IKDC scores resulting in a clinical failure rate of 96% (24 of the 25 living patients) at a mean 14-year follow-up. Conclusion: PMM for medial meniscus posterior horn root tears demonstrated 72% progression to TKA and 96% failure according to subjective clinical outcomes at a minimum 10-year follow-up.

Objectives: Radial tears of the meniscus are increasingly treated with repair instead of partial meniscectomy, with satisfactory short-term clinical outcomes. There remains a paucity of mid- and long-term outcomes data for this preservation technique. The purpose of this study was to 1) evaluate the mid- to long-term clinical outcomes and reoperation rate of radial meniscal repair versus bucket-handle meniscal repair and 2) evaluate the outcomes of both surgeries overtime. We hypothesized that radial repair would provide similar outcomes and reoperation rates to that of bucket-handle meniscal repair in this propensity-matched cohort. Methods: A previously identified cohort of radial meniscal tears without concurrent root injuries undergoing surgical repair at a single institution between 2011 and 2015 were reviewed. Inclusion criteria was patients undergoing repair of full-thickness radial tears. Exclusion criteria were patients who had 1) not consented for research follow-up, 2) <2 year of follow-up, 3) high-grade (Outerbridge grade 3 or 4) chondromalacia, 4) knee dislocations or combined anterior cruciate ligament and posterior cruciate ligament injuries, 5) repair of posterior meniscal root tears, and 6) repair of partial radial tears. Propensity matching was performed based on age at surgery, sex, laterality, body mass index (BMI), and concomitant anterior cruciate ligament reconstruction (ACLR) using a comparison pool of 70 bucket-handle meniscal repairs (BHMR). Reoperation-free survival rates, Tegner Activity Score, visual analog scale (VAS) for pain, and International Knee Documentation Committee (IKDC) scores were analyzed. Results: Twenty-four patients (18 males, 6 females, age 22.8 ± 11.9 years, BMI 26.5 ± 5.8) with radial meniscal repair were included in this study. Eighteen of these patients were successfully propensity matched to 18 bucket-handle meniscal tears for an overall mean follow-up of 10.2 ± 1.7 years (range, 7.3-13.5) (Table 1). The 24 radial tear repairs demonstrated significant and durable postoperative improvements at mean 10.2 years across VAS at rest (3.0 ± 2.5 vs 0.5 ± 1.0, p < 0.001), VAS for pain at use (5.8 ± 2.9 vs 1.4 ± 1.9, p < 0.001) Tegner (2.6 ± 1.4 vs 6.8 ± 2.0, p < 0.001) and IKDC (39.8 ± 12.3 vs 84.1 ± 16.5, p < 0.001) (Table 1). Of patients not undergoing reoperation (19), 100% reported being “Satisfied” 4/19 (21%) or “Very Satisfied” 15/19 (79%). When the 18 radial tear repairs were compared to the 18 BHMT repairs, there was no significant difference across VAS for pain at rest (0.6 ± 1.2 vs 0.3 ± 0.7, p = 0.48), VAS for pain at use (1.6 ± 2.1 vs 1.1 ± 1.3, p = 0.48) Tegner (6.9 ± 2.2 vs 6.4 ± 2.1, p = 0.51) and IKDC (83.4 ± 17.4 vs 82.1 ± 14.1, p = 0.83) (Table 2). Importantly, survival without reoperation rates were not statistically different between the 2 groups at 10-year follow-up (14/18 (78%) vs 16/18 (89%), p = 0.37) (Figure 1). There was no significant difference between clinical outcomes (Tegner and IKDC) at final follow-up in the radial repair group as compared to the 4-year mid-term outcomes (p = 0.58 and 0.19 respectively). For the BHMR group, Tegner scores were not significantly different (p = 0.60) compared with their 4-year timepoint; however, IKDC scores at the final timepoint were significantly lower 93.4 ± 3.4 vs 82.1 ± 14.1 (p = 0.01). Notably, both the radial repair and bucket-handle repairs groups reported final follow-up Tegner scores that were not significantly different from their preinjury Tegner scores (p = 0.70 for the radial group and p = 0.62 for the bucket-handle group). Conclusions: At mean 10-year follow-up, significant clinical improvements and high rates of satisfaction were observed for radial meniscal tear repair. When propensity matched, radial and BHMR demonstrated durable improvements in postoperative VAS for pain, IKDC, and Tegner scores, as well as similar, acceptable reoperation rates. [Figure: see text]