Saris, Daniël B.F.

Purpose To identify risk factors for medial meniscus posterior root tears (MMPRT) and arthroplasty‐free survival in postmenopausal women, while secondary objectives included analyzing menopause‐specific factors associated with MMPRT and defining risk factors for conversion to arthroplasty in patients with a confirmed MMPRT. Methods All patients at our institution with a diagnosed meniscal tear through December 2024 were identified. From this cohort, women with a menopausal diagnosis preceding their meniscal tear were matched one‐to‐one with men by age and body mass index. Imaging studies were reviewed to identify MMPRTs. Subsequent arthroplasty, Charlson Comorbidity Index, menopausal type (surgical or physiologic), hormone replacement therapy, bisphosphonate usage, and bone mineral density were recorded. Logistic and Cox regression were used to define risk factors for MMPRT and arthroplasty; survivorship was determined using Kaplan‐Meier analyses. Results The final cohort consisted of 1564 patients (n = 782 women) with a median age of 63 years, of which 244 patients (15.6%) had MMPRT. Age and female sex were associated with MMPRT. The presence of an MMPRT, female sex, body mass index, and Charlson Comorbidity Index were associated with arthroplasty. Among postmenopausal women, age at menopause, surgical menopause, hormone replacement therapy, and bone mineral density were associated with MMPRT. For patients with MMPRT, female sex was associated with arthroplasty. Ten‐year survivorship‐free from arthroplasty in patients with MMPRT was 53.5% for women and 78.4% for men ( P = .02). Conclusions Postmenopausal status, age, and hormone replacement therapy usage are risk factors for MMPRT. Compared with men, postmenopausal women with MMPRT exhibit reduced arthroplasty‐free survival, underscoring the need for targeted interventions. Level of Evidence Level III, retrospective comparative study.

Purpose To assess the reliability, predictability, and discriminative capacity of 3 anatomic measurements, tibial tubercle‐trochlear groove (TT‐TG), tibial tubercle‐posterior cruciate ligament, and patellar tendon‐lateral trochlear ridge (PT‐LTR), where PT‐LTR may offer a complementary approach to assessing recurrent patellofemoral instability (PFI) risk. Methods Patients diagnosed with PFI before primary patellofemoral stabilization surgery at a single institution between 2022 and 2024 were included. A control group without PFI was propensity matched 1:1 for age, sex, and laterality. Magnetic resonance images were evaluated to measure TT‐TG, tibial tubercle‐posterior cruciate ligament, and PT‐LTR. A priori power analysis determined the cohort size. Statistical analyses compared differences between the PFI and control groups with Student t‐tests, receiver operating characteristic analyses, and area under the curve with resultant sensitivity, specificity, and an optimal cutoff. Results Patients included 50 knees with PFI (28 women, 22 men; mean age 18 ± 5 years). The control group included 50 knees (27 women, 23 men; mean age 18 ± 4 years). Excellent inter‐ and intra‐rater reliability (intraclass correlation coefficient > 0.7) was shown for TT‐TG and PT‐LTR in the PFI and control groups. The distances for TT‐TG, tibial tubercle‐posterior cruciate ligament, and PT‐LTR were significant predictors ( P ≤ .025) of PFI. The average PT‐LTR distance difference for the PFI and control groups was 7.0 mm ( P < .001). PT‐LTR showed an area under the curve of 0.80 and, when ≥4.6 mm, was 66% sensitive and 92% specific for PFI. Conclusions The PT‐LTR distance is a reliable and discriminative metric for identifying PFI in both pediatric and adult populations. A PT‐LTR cutoff value of 4.6 mm showed diagnostic discrimination and substantially high specificity for recurrent PFI, indicating strong ability to identify patients with instability. Level of Evidence Level III, retrospective case control study.

Purpose To evaluate implantation rates, time to implantation, and predictors of implantation following matrix‐induced autologous chondrocyte implantation (MACI) biopsy for knee chondral defects. Methods Patients undergoing MACI biopsy or implantation for symptomatic knee chondral defects from 2017 to 2024 at a single institution were reviewed. At a minimum 1‐year follow‐up, the decision to proceed with implantation, recurrent symptoms, complications, and reoperations were assessed. Kaplan‐Meier analysis estimated time to implantation, and multivariable logistic regression identified predictors of MACI implantation. Results A total of 208 knees in 202 patients (mean age 28.0 ± 10.9 years, range 11‐59) underwent MACI biopsy for 243 chondral defects (patella [38%], femoral condyle [34%], and trochlea [26%]). At a mean follow‐up of 4.3 years (range 1.0‐8.3), 64 knees (31%) proceeded to second‐stage MACI implantation. Among 144 knees not implanted, 87 (60%) reported symptom improvement, and 26 (18%) had persistent symptoms. The remaining 22% did not undergo implantation due to another cartilage procedure, insurance denial, or pending scheduling. Patients who underwent biopsy at the home institution had a shorter time from biopsy to implantation compared with those biopsied at outside institutions (6.1 vs 13.1 months, P = .001). Median time to implantation was 9.4 months (95% confidence level: 7.2‐12.2) for home biopsies. Lower body mass index was associated with progression to implantation after adjusting for covariates (odds ratios 0.92, P = .019). Patients implanted within 4 months had larger chondral defects (4.0 vs 3.0 cm 2 , P = .045). At a mean 4.1‐year follow‐up, 6 patients (8%) experienced postoperative complications, including 3 (4%) who required revision chondroplasty. Conclusions MACI biopsy for knee chondral defects resulted in approximately one‐third of patients proceeding to MACI implantation, at a median of 9.4 months after biopsy. Lower body mass index was associated with higher likelihood of progression to implantation, larger chondral defects with earlier implantation, and among patients who did not proceed to implantation, approximately 60% reported symptom improvement following concomitant chondroplasty at the time of biopsy. Level of Evidence Level IV, retrospective case series.

Background: Increased posterior tibial slope (PTS) has been associated with higher revision rates after anterior cruciate ligament reconstruction (ACLR). Whether the addition of lateral extra-articular tenodesis (LET) mitigates the risk associated with increased PTS is unclear. Purpose: To determine the prevalence of increased PTS (≥12°) in a young high-risk primary ACLR population and evaluate whether LET is associated with lower revision rates in patients with increased PTS. Study Design: Cohort study; Level of evidence, 3. Methods: This study included patients aged ≤25 years undergoing primary ACLR across 3 high-volume centers with ≥2 years between surgery and data collection. PTS was measured on lateral radiographs for medial and lateral plateaus. Primary analyses consisted of 4 prespecified multivariable logistic regression models with different PTS operationalizations as continuous predictors per 1° increase (medial PTS, lateral PTS, the maximum [PTSmax], and the lateral-medial difference), adjusted for patient and surgical covariates including graft type, with surgical center as a fixed effect. Secondary analyses used PTS dichotomized at 12°; revision rates were compared between isolated ACLR and ACLR with LET, with the treatment effect quantified as absolute risk reduction and number needed to treat. Results: A total of 780 patients were included; 84 (10.8%) underwent revision ACLR. Increased PTS (≥12°) was present in 28.2% of patients and more common in those requiring revision (38.6% vs 27.0%; P = .03). In patients with PTSmax ≥12°, revision occurred in 21.0% without LET and 9.2% with LET (absolute risk reduction, 11.8% [95% CI, 2.3%-21.3%]; number needed to treat, 9); in patients with PTSmax <12°, revision occurred in 13.2% without LET and 5.4% with LET (absolute risk reduction, 7.8% [95% CI, 3.0%-12.6%]; number needed to treat, 13). In the 4 prespecified multivariable models with PTS as a continuous predictor, LET was independently associated with substantially lower odds of revision ACLR (odds ratio [OR], 0.37; 95% CI, 0.22-0.62; P < .001). Lateral PTS (OR, 1.09 per 1° increase; 95% CI, 1.00-1.18; P = .04) and PTSmax (OR, 1.09; 95% CI, 1.00-1.19; P = .04) were independently associated with revision ACLR. The lateral-medial PTS difference was not associated with revision ACLR. Conclusion: In a young high-risk primary ACLR population, increased PTS was present in nearly 30% of patients. LET was associated with a lower risk of revision irrespective of PTS, while increased PTS was independently associated with revision ACLR.

Background: Total knee arthroplasty (TKA) is the treatment of choice for end-stage knee osteoarthritis in many patients. In younger patients with predominantly medial compartment disease, high tibial osteotomy (HTO) is performed as a joint-preserving treatment. However, concerns remain regarding potentially compromised outcomes of TKA after previous HTO given the axial deviation, osteotomy site, secondary surgery, previous hardware, and instrumentation. Therefore, this study compared long-term implant survival, revision, and infection rates, and patient-reported outcomes between patients undergoing TKA after HTO and matched TKA-only controls. Methods: Postoperative complications and revision surgeries were prospectively recorded in patients who underwent TKA from 2000 to 2023 at a single academic center. Patients with previous ipsilateral HTO formed the study group and were propensity matched 1:2 to TKA-only patients without a previous osteotomy based on age, sex, and body mass index. Knee Society Scores (KSS) were collected prospectively. Implant survivorship was analyzed using Kaplan-Meier survival curves and Cox proportional hazards models. Results: The study included 134 HTO-TKA and 268 matched TKA-only patients, with a mean follow-up of 10.5 ± 6.4 years (range: 0-24 years) after TKA. Both groups showed significant postoperative improvements in KSS (p < 0.02) with comparable clinical outcomes (HTO-TKA: 79.0 (6.0), TKA-only: 79.0 (11.8)). Revision arthroplasty rates were 5.2% for HTO-TKA and 4.5% for TKA-only (p = 0.69); the mean time to revision was 8.1 ± 8.7 years vs. 4.4 ± 3.5 years, respectively (p = 0.30). Infection rates were 2.2% and 1.1%, respectively (p = 0.74). Conclusions: Revision and infection rates were comparable between HTO-TKA and matched TKA-only patients, with no statistically significant differences. Our findings demonstrate comparable patient-reported outcomes in both groups. These findings indicate that a previous HTO does not adversely affect TKA implant longevity or clinical outcomes when compared with matched primary TKA patients within the US population. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

ABSTRACT Premature physeal closure occurs following trauma, cancer, or infection. Current treatments have poor success rates. With recent pediatric donor tissue availability, physeal allograft transfer (PAT) can now be considered. The purpose of this study was to study the safety and feasibility of PAT in a large animal model. The aim of this study is to gather foundational data to inform future studies into the efficacy of PAT. Physeal defects were created in the distal femur of nine female domestic swine and treated with PAT from two male donor pigs, cementation, or bone autograft. Viability was assessed. After 3 months, physes were visualized using CT and MRI. Integration, tissue composition, donor DNA presence, and microscopic appearance were evaluated. Physeal allografts demonstrated 93% viability after procurement and preservation. All animals reached the 3‐months study endpoint without gross deformations. No physeal bars formed in any group. Cystic changes were seen in experimental and control femurs. All groups showed disorganized tissue architecture without growth plate recapitulation. High allografts viability and structural integrity after procurement support the potential of this treatment. Although no gross deformities were found, transferred physes demonstrate poor integration and incomplete repair. The lack of physeal bar formation in the control group limits the reliability of the animal model for studying physeal allograft transfer. Lastly, this study was designed as a feasibility study and lacks power to compare treatment effects statistically. The efficacy of PAT for preventing growth arrest remains undetermined.

Cartilage defects remain a prevalent and challenging clinical problem, especially in young, active individuals. Existing treatments such as microfracture or autologous chondrocyte implantation either lack durability or require multiple surgeries and extensive cell culture. To address these limitations, we developed RECLAIM—a one-stage, two-cell-type procedure combining allogeneic mesenchymal stromal cells and autologous chondrons. RECLAIM harnesses the trophic and immunomodulatory properties of MSCs to stimulate autologous chondron-driven tissue repair, minimizing invasiveness while optimizing biologic regeneration. This article reviews the preclinical discovery, clinical translation, trial results, and platform potential of RECLAIM, which was recognized with the 2025 Arnold I. Caplan Award for Distinguished Research in OrthoBiologics. Our work builds on Professor Caplan's pioneering conceptualization of MSCs as “medicinal signaling cells” and establishes a model for academic, investigator-driven translation of regenerative science into clinical practice.

Background: Patellofemoral instability (PFI) is a condition that leads to recurrent dislocation events and is typically secondary to extensor mechanism malalignment and rotational deformities. To correct malalignment, a tibial tubercle osteotomy (TTO) can be performed; however, an understanding of the associated complications, recurrence rates, and potential for reoperation is necessary. Purpose: To systematically review the literature to determine the incidence of postoperative complications, rate of recurrent instability, and all-cause reoperation rate after TTO for PFI. Study Design: Systematic review; Level of evidence 4. Methods: The Cochrane Database of Systematic Reviews, PubMed, Embase, MEDLINE, and CINAHL were queried for studies that reported complications after TTO. No date limits were applied. A total of 1050 studies were identified. Complications were categorized into “minor” and “major” groups using a modified Clavien-Dindo Classification. A meta-analysis was conducted to examine complication rates, recurrent instability, and all-cause reoperation, utilizing a DerSimonian and Laird random-effects model. A meta-analysis for recurrent instability was subgrouped according to follow-up periods of ≤2 years and >2 years. Results: A total of 38 studies were included, comprising 1546 patients, representing 1733 knees. The study dates ranged from 1989 to 2024, and the level of evidence ranged from 2 to 4. The weighted mean age at surgery was 24.1 years (range, 20-54 years), and 67% of patients were women. The weighted mean follow-up of all studies was 4.2 years. Overall, 197 minor complications, 39 major complications, 90 recurrent instability events, and 275 reoperations were identified. The minor complication rate was 9% (range, 0%-65% [95% CI, 6%-13%]). The major complication rate was 3% (range, 0%-10% [95% CI, 3%-4%]). Seven studies had a ≤2-year follow-up, and the remaining 31 studies had a >2-year follow-up. The recurrent instability rate was 3% in studies with ≤2 years of follow-ups (range, 0%-26% [95% CI, 1%-13%]). In studies with >2 years of follow-up, the recurrent instability rate was 8% (range, 0%-31% [95% CI, 6%-12%]). The all-cause reoperation rate was 16% (range, 0%-54% [95% CI, 11%-21%]). Conclusion: This systematic review and meta-analysis identified the incidence of complications (17%), the rate of recurrent instability (3%-8%), and the all-cause reoperation rate (16%) after TTO. TTO, performed alone or in combination with medial patellofemoral ligament reconstruction for the treatment of PFI, reliably improved clinical outcome scores in the setting of variable complication rates. Interestingly, rates of recurrent instability increased over time, and most reoperations were undertaken for hardware removal rather than revision patellar stabilization surgery.

Background: Treatment decisions in patients with anterior cruciate ligament (ACL) injuries are influenced by multiple factors, such as the desire to return to sports or symptomatic instability. Identifying the differential treatment effect of ACL reconstruction (ACLR) compared with nonoperative management on a patient-specific level can inform surgical decision-making. Hypothesis: Unsupervised machine learning can identify distinct patient subgroups based on outcome achievement after ACL injury, and ACLR will exert a protective effect on the development of posttraumatic osteoarthritis (PTOA) over nonoperative management. Study Design: Cohort study; Level of evidence, 3. Methods: A longitudinal populational registry identified patients with ACL injuries from 1990 to 2016 with a minimum 7.5-year follow-up. An unsupervised random forest algorithm was utilized to develop and validate patient subgroups. Treatment effects of ACLR on outcomes were analyzed using a machine learning causal inference estimator. Patient subgroup membership was incorporated into a multivariable logistic regression to identify factors predictive of optimal outcomes. Results: A total of 923 patients (785 primary ACLR, 138 nonoperative) were included. The random forest algorithm arrived at an optimal partition of 2 subgroups, with 653 patients in the optimal outcome subgroup (368 male [56.4%]; mean age, 26.0 ± 10.2 years; mean body mass index [BMI], 26.5 ± 4.30) and 270 patients in the suboptimal outcome subgroup (152 male [56.3%]; mean age, 35.0 ± 10.1 years; mean BMI, 30.5 ± 5.54). The latter group demonstrated significantly increased rates of secondary meniscal injury, development of symptomatic PTOA, and progression to total knee arthroplasty (TKA) at the final follow-up (all P < .01). In the optimal outcome subgroup, ACLR had significantly protective treatment effects on the risk of secondary meniscal injury (average treatment effect [ATE], 61%), contralateral ACL injury (ATE, 8%), symptomatic PTOA (ATE, 16%), and progression to TKA (ATE, 6%) (all P < .01). Conversely, in the suboptimal outcome subgroup, ACLR only protected against symptomatic PTOA (ATE, 11%) and progression to TKA (ATE, 8%) (both P < .01). Conclusion: Two clinically meaningful subgroups were identified from retrospectively collected data and found to experience differential treatment responses after ACL injuries. ACLR decreased the rate of development of PTOA and TKA in both subgroups but was not as effective in preventing secondary meniscal injuries or contralateral ACL injuries in patients who were older, heavier, or had concomitant medial meniscus injuries.