Incidence of Complications After Tibial Tubercle Osteotomy and Tibial Tubercle Osteotomy With Distalization.

BACKGROUND: Tibial tubercle osteotomy (TTO) is a well-established surgical treatment option for patellofemoral instability and pain. TTO with distalization (TTO-D) is indicated for patients with patellofemoral instability, patellar malalignment, and patella alta. The current literature demonstrates several complications that may be associated with TTO, with reportedly higher rates of complications associated with TTO-D. PURPOSE: To analyze and compare complication rates after TTO without distalization (TTO-ND) and TTO-D and assess risk factors associated with complications. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: All skeletally mature patients who underwent TTO with or without distalization by a single surgeon between September 2014 and May 2023 with a minimum of 6 months of clinical follow-up were retrospectively reviewed. Patient factors, surgical indications, perioperative data, and complications were collected via a retrospective review of electronic medical records. Concomitant procedures were categorized as intra-articular, extra-articular, and osteotomies. RESULTS: A total of 251 TTOs (117 TTO-D, 134 TTO-ND) were included in the study group. Postoperative complications were observed in 15 operations (6%), with arthrofibrosis as the most common complication (10 operations [4%]). TTO-D and TTO-ND had similar rates of complication (5% vs 7%; P = .793). Clinical nonunion was observed in 3 operations (3%) in the TTO-D cohort and 1 operation (1%) in the TTO-ND cohort. In the TTO-D cohort, concomitant intra-articular procedures were significantly associated with an increased likelihood of complications in a univariate model. In the TTO-ND cohort, an increased tourniquet time was significantly associated with an increased likelihood of complications in a univariate model. For all TTOs as well as the TTO-D and TTO-ND cohorts, there were no significant associations between patient or surgical variables in a multivariate model. CONCLUSION: TTO with and without distalization is a safe procedure with low rates of complication. TTO-D was not associated with a higher rate of complications compared with TTO-ND. There was no association between complications and surgical variables for TTO procedures.

Decreased Effective Patellar Tendon Length following Distalization Tibial Tubercle Osteotomy without Patellar Tendon Tenodesis.

Background: Distalization tibial tubercle osteotomy (TTO) is an effective treatment for improving patellar height in patients with patella alta associated with patellofemoral instability and cartilage lesions. The addition of a patellar tendon tenodesis has been suggested; nonetheless, concerns exist regarding possible increased patellofemoral cartilage stresses. Purpose: To evaluate pre- and postoperative patellar tendon length and alignment parameters on magnetic resonance imaging (MRI), as well as patient-reported outcome measures (PROMs) after distalization TTO without patellar tendon tenodesis. Study Design: Case series; Level of evidence, 4. Methods: Twenty skeletally mature patients who underwent distalization TTO with or without anteromedialization at our institution between December 2014 and August 2021 were included. All patients underwent pre- and postoperative MRIs of the affected knee. The Caton-Deschamps index (CDI), the axial and sagittal tibial tubercle-trochlear groove (TT-TG) distances, the distances from the tibial plateau to the patellar tendon insertion and the tibial tubercle, and the patellar tendon length were assessed. PROMs included the International Knee Documentation Committee Subjective Knee Evaluation Form, the Knee injury and Osteoarthritis Outcome Score-Quality of Life subscale, the Kujala Anterior Knee Pain Scale, and the Veterans RAND 12-Item Health Survey mental and physical component scores. Results: The mean patient age at surgery was 27.4 years (range, 14-42 years). Radiographic parameters demonstrated improved patellar height (CDI decreased from 1.36 to 1.11; P < .001) after distalization TTO. The distance from the tibial plateau to the patellar tendon insertion significantly decreased from 20.1 mm preoperatively to 17.9 mm postoperatively (P < .020), and the patellar tendon length decreased from 53.4 mm preoperatively to 46.0 mm postoperatively (P < .001). The patellar tendon insertion was not distalized after distalization TTO, likely because of scarring of the patellar tendon proximal to the osteotomy site. Patients demonstrated significant pre- to postoperative improvements on all PROMs (P≤ .024 for all ). There were 4 (20%) complications-2 cases of arthrofibrosis, 1 postoperative infection, and 1 osteotomy delayed union. Conclusion: Distalization TTO without patellar tendon tenodesis was associated with improved radiographic outcomes and PROMs. It provides an additional tool for surgical management of patellofemoral pathology with associated patella alta.

Medial Meniscus Posterior Root Tears Lead to Changes in Joint Contact Mechanics at Low Flexion Angles During Simulated Gait.

BACKGROUND: Previous biomechanical studies evaluating medial meniscus posterior root tears (MMPRTs) are limited to low loads applied at specified loading angles, which cannot capture the effects of MMPRTs during the multidirectional forces and moments placed across the knee during physiological activities. PURPOSE: To quantify the effects of MMPRTs on knee joint contact mechanics during simulated gait. STUDY DESIGN: Controlled laboratory study. METHODS: Six human cadaveric knees were mounted on a robotic simulator programmed to apply dynamic forces, moments, and flexion angles to mimic level walking. Twelve cycles of multidirectional and dynamic standard gait input waveforms, normalized to specimen-specific body weight, were applied to the following conditions: (1) native, intact meniscus and (2) MMPRT. Peak contact stress, contact area, and the position of the weighted center of contact across the medial tibial plateau throughout the stance phase of gait were quantified using an electronic sensor placed across the medial tibial plateau. The difference between the intact state and MMPRT condition was calculated for each metric, and then the means and 95% CIs were computed. RESULTS: Despite heterogeneity in knee contact forces, MMPRTs significantly increased peak contact stress by a mean of 2 MPa across 20% to 37% of the simulated gait cycle and significantly decreased the contact area by a mean of 200 mm2 across 16% to 60% of the simulated gait cycle in comparison with the native state. There was no significant difference in the position of the weighted center of contact, in either the anterior-posterior or medial-lateral directions, after MMPRT. CONCLUSION: MMPRTs led to both a significant increase in peak contact stress and decreased contact areas for a portion of the simulated gait cycle ranging from 20% to 37% of gait, during which time the femur was flexed <15°. CLINICAL RELEVANCE: Contact mechanics are significantly affected after MMPRTs during early to midstance and at knee flexion angles lower than demonstrated previously. These data provide further biomechanical justification for treating MMPRTs.

Systematic Review of Clinical Outcomes After Proximal Tibia Anterior Closing-Wedge Osteotomy With ACL Reconstruction.

Background: While increased posterior tibial slope (PTS) is an important risk factor for failure after anterior cruciate ligament (ACL) reconstruction, controversy exists regarding indications and outcomes of proximal tibia anterior closing-wedge osteotomy (ACWO) with concomitant ACL reconstruction in patients with ACL tears. Purpose: To assess clinical outcomes after combined ACL reconstruction and proximal tibia ACWO. Study Design: Systematic review; Level of evidence, 4. Methods: In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines, we performed a systematic review of the existing literature on ACWO and ACL reconstruction using PubMed (MEDLINE), Cochrane Library, Scopus, and Embase. The search phrases included "anterior closing wedge osteotomy,""anterior closing wedge tibial osteotomy,""anterior closing wedge proximal tibial osteotomy,""anterior cruciate ligament," and "revision anterior cruciate ligament." Non-English publications and single-patient case reports were excluded. Extracted data included study details, patient demographics, patient-reported outcomes (PROs), clinical outcomes, radiographic outcomes, complications, and return-to-sport (RTS) rates. Results: A total of 6 studies with 110 patients (110 knees) were included. Two-stage ACWO and ACL reconstruction was reported in 2 studies of 78 patients (71%), while a single-stage technique was reported in 4 studies of 32 patients (29%). ACWO was performed in the setting of primary ACL tear in 23 patients (21%) and in recurrent ACL tear in 87 patients (79%). Patients demonstrated postoperative improvements in Lysholm, pivot-shift test, and side-to-side difference in anterior tibial translation. After ACWO, all studies reported mean postoperative PTS of <10° (range, 4.4°-9.2°). Of patients with available RTS data (n = 43), the same-level RTS rate ranged from 65% to 100%. A two-stage procedure reported in 1 study had a lower RTS rate (n = 13 of 20 [65%]) than that of 2 studies with single-stage procedure (n = 4 of 5 [80%] and n = 18 of 18 [100%]). The overall complication rate was 0.9% to 1.3%, and there were no reported ACL retears. Conclusion: The current evidence, which is constrained by the quantity and quality of studies, showed that ACWO with single- or two-stage ACL reconstruction in patients with ACL insufficiency and increased PTS was associated with significant improvements in PROs and high RTS rates.

Male sex is an independent risk factor for patellar osteochondral fractures following acute patellar dislocation in pediatric patients.

PURPOSE: Although most patellar dislocations are associated with medial patellofemoral ligament (MPFL) injury, many patients also sustain concomitant patellar osteochondral fractures following a patellar dislocation. Few prior studies have described or evaluated risk factors for patellar osteochondral fractures in pediatric patients. The purpose of the present study was to describe the incidenceand location of patellar osteochondral fractures following acute patellar dislocation in pediatric patients. In addition, we described risk factors for patellar osteochondral fractures in this population. We hypothesized that most fractures would occur at the inferomedial quadrant of the patella following a traumatic injury mechanism. METHODS: Following Institutional Review Board approval, the electronic medical record was queried to identify pediatric patients ≤ 18 years old who underwent MPFL reconstruction (MPFLR) or non-operative treatment for patellar instability between July 2016 and February 2020. Osteochondral fractures were defined as full-thickness chondral injuries with attached subchondral bone or purely osseous injuries measuring ≥ 3 mm (mm) in at least two magnetic resonance imaging (MRI) planes. Patients were included in the study if they had complete preoperative x-ray and MRI studies with minimum 6-month follow-up. Patients were excluded if they had incomplete imaging, isolated chondral fractures, or less than 6 months follow-up. Univariate analysis was used to identify patient factors associated with osteochondral fractures. Multivariate regression analysis was used to identify risk factors for osteochondral fractures. RESULTS: Sixty patients (63 knees) were included in the study, 15 (23.8%) of whom had a patellar osteochondral fracture. The majority of osteochondral fractures (87%) involved the inferomedial quadrant of the patella. Univariate analysis showed an association between male sex (p = 0.041), skeletal immaturity (p = 0.028), and decreased patellar tilt (p = 0.021) and patellar osteochondral fractures. Multivariate regression analysis identified male sex as an independent risk factor for osteochondral fractures (relative risk: 4.8, 95% confidence interval [CI]: 1.08-20.9, p = 0.039). No patients had recurrent dislocation at minimum 6-month follow-up. All patients with osteochondral fractures returned to sports at most recent follow up. CONCLUSION: In this study, 23% of pediatric patients with acute patellar dislocations have a concomitant patellar osteochondral fracture. The majority of patellar osteochondral fractures involve the inferomedial quadrant of the patella. Male sex is an independent risk factor for patellar osteochondral fractures, and skeletal immaturity is associated with patellar osteochondral fractures in this population. LEVEL OF EVIDENCE: Level III.

High degree of alignment precision associated with total knee arthroplasty performed using a surgical robot or handheld navigation.

PURPOSE: The purpose of this study was to compare the precision of bony resections during total knee arthroplasty (TKA) performed using different computer-assisted technologies. METHODS: Patients who underwent a primary TKA using an imageless accelerometer-based handheld navigation system (KneeAlign2®, OrthAlign Inc.) or computed tomography-based large-console surgical robot (Mako®, Stryker Corp.) from 2017 to 2020 were retrospectively reviewed. Templated alignment targets and demographic data were collected. Coronal plane alignment of the femoral and tibial components and tibial slope were measured on postoperative radiographs. Patients with excessive flexion or rotation preventing accurate measurement were excluded. RESULTS: A total of 240 patients who underwent TKA using either a handheld (n = 120) or robotic (n = 120) system were included. There were no statistically significant differences in age, sex, and BMI between groups. A small but statistically significant difference in the precision of the distal femoral resection was observed between the handheld and robotic cohorts (1.5° vs. 1.1° difference between templated and measured alignments, p = 0.024), though this is likely clinically insignificant. There were no significant differences in the precision of the tibial resection between the handheld and robotic groups (coronal plane 0.9° vs. 1.0°, n.s.; sagittal plane 1.2° vs. 1.1°, n.s.). There were no significant differences in the rate of overall precision between cohorts (n.s.). CONCLUSIONS: A high degree of component alignment precision was observed for both imageless handheld navigation and CT-based robotic cohorts. Surgeons considering options for computer-assisted TKA should take other important factors, including surgical principles, templating software, ligament balancing, intraoperative adjustability, equipment logistics, and cost, into account. LEVEL OF EVIDENCE: III.

Proximal bone block with distal screw trajectory improves mechanical stability during distalization tibial tubercle osteotomy.

PURPOSE: The purpose of this study was to quantify differences in mechanical stability of a wedge-shaped distalization tibial tubercle osteotomy (TTO) with a standard technique, versus a modified technique with use of a proximal bone block and distally angled screw trajectory. METHODS: Ten fresh-frozen cadaver lower extremity specimens (five matched pairs) were utilized. Within each specimen pair, one specimen was randomly assigned to undergo a standard distalization osteotomy fixed with two bicortical 4.5-mm screws oriented perpendicular to the long axis of the tibia, and the other to undergo a distalization osteotomy with modified fixation utilizing a proximal bone block and distally angled screw trajectory. Each specimen's patella and tibia were mounted on a servo-hydraulic load frame using custom fixtures (MTS Instron). The patellar tendon was dynamically loaded to 400 N at a rate of 200 N/second for 500 cycles. Following the cyclic loading, loading to failure was done at 25 mm/min. RESULTS: The modified distalization TTO technique demonstrated significantly higher average load to failure compared to the standard distalization TTO technique (1339 N vs. 844.1 N, p < 0.001). Average maximum tibial tubercle displacement during cyclic loading was significantly smaller in the modified TTO technique group compared to the standard TTO technique (1.1 mm vs. 4.7 mm, p < 0.001). CONCLUSION: This study demonstrates that distalization TTO utilizing a modified technique with a proximal bone block and distally aimed screws is biomechanically superior to standard distalization TTO without proximal bone block and screw trajectory perpendicular to the long axis of the tibia. This increased stability may aid in reducing the reported higher complication rates (including loss of fixation, delayed union and nonunion) following distalization TTO, although future clinical outcome studies are warranted.

Patellofemoral arthroplasty conversion to total knee arthroplasty: An updated retrieval analysis and clinical outcomes.

BACKGROUND: A prior retrieval analysis found high rates of infection after conversion of PFA to TKA, but was limited by a small sample size. The purpose of this study is to perform a retrieval analysis with clinical correlation on an expanded group of patients to better understand conversion of PFA to TKA. METHOD: A retrospective review of an implant retrieval registry identified 62 conversions of PFA to TKA between 2004-2021. Implants were analyzed for wear pattern and cement fixation. Patient charts were reviewed for demographic information, perioperative data, prior and subsequent surgical procedures, complications and outcomes. Radiographs performed prior to index PFA and conversion procedures were assessed for KL grading. RESULTS: Cement fixation was present on 86% of retrieved components and wear was more pronounced on the lateral side. The most common indication for conversion to TKA was progression of OA in 46.8% of patients, followed by unexplained pain in the absence of radiographic or clinical changes (37.1%), loosening (8.1%), mechanical symptoms (4.8%), traumatic (3.2%). Thirteen patient experienced complications requiring additional procedures including arthrofibrosis (n = 4, 7.3%), PJI (n = 3, 5.5%), instability (n = 3, 5.5%), hematoma (n = 2, 3.6%) and loosening (n = 1, 1.8%). Revision components were used in 1.8% of cases and average post-conversion arc of motion was 119 degrees. CONCLUSIONS: The most common reason for PFA conversion to TKA was progression of osteoarthritis. PFA conversion to TKA is technically similar to primary TKA, but complication rates are more consistent with revision TKA in this study.

Comprehensive Review of Multidirectional Instability of the Shoulder.

Multidirectional instability of the shoulder can result from underlying atraumatic laxity, from repetitive microtrauma, or from a traumatic injury and often occurs in association with generalized ligamentous laxity or underlying connective tissue disorders. It is critical to differentiate multidirectional instability from unidirectional instability with or without generalized laxity to maximize treatment success. Although rehabilitation is still considered the primary treatment method for this condition, surgical treatment in the form of open inferior capsular shift or arthroscopic pancapsulolabral plication is indicated if conservative treatment fails. Recent biomechanical and clinical research has shown that there is still room for improvement in the treatment methods offered to this specific patient cohort. Potential treatment options, such as various methods to improve cross-linking of native collagen tissue, electric muscle stimulation to retrain the abnormally functioning dynamic stabilizers of the shoulder, and alternative surgical techniques such as coracohumeral ligament reconstruction and bone-based augmentation procedures, are brought forth in this article as potential avenues to explore in the future.

Assessment of Patellar Vascularity after Patellar Cartilage Restoration via Lateral Parapatellar Approach: Analysis Using Dynamic Contrast-Enhanced Magnetic Resonance Imaging.

OBJECTIVE: Patellofemoral cartilage restoration procedures, including osteochondral allograft, particulated juvenile cartilage, and matrix-induced autologous chondrocyte implantation, have been shown to be effective treatments for patellofemoral cartilage lesions. However, concerns exist regarding disruption of the patellar vascular supply and secondary stabilizers of the patellofemoral joint during medial parapatellar approaches, especially when combined with a lateral release. A lateral parapatellar approach affords the possibility of avoiding disruption of the medial blood supply to the patella, while also allowing laterally-based soft tissue stabilization procedures. The purpose of this study was to investigate in vivo changes in patellar vascularity following patellofemoral cartilage restoration procedures performed via a lateral parapatellar approach via use of dynamic contrast-enhanced magnetic resonance (MR) imaging. DESIGN: This study is a prospective case series of 5 adult patients undergoing patellofemoral cartilage restoration procedures via a lateral parapatellar approach with pre-operative and post-operative dynamic contrast-enhanced MR imaging to assess changes in patellar vascularity. Secondary outcomes included knee range of motion, need for revision surgery, and complications. RESULTS: There was no significant post-operative difference in patellar vascularity in patients undergoing patellofemoral cartilage restoration procedures via a lateral parapatellar approach, as evaluated by qualitative MR imaging. CONCLUSION: Our results suggest that a lateral parapatellar approach for cartilage restoration procedures may preserve patellar vascularity, while also allowing for lateral release to be performed through the same incision.

No difference in patient reported outcomes between cohorts undergoing lesion-specific surgery for osteochondritis dissecans of the knee.

Introduction: There is a paucity of data on patient reported outcome measures (PROMs) associated with surgical treatment of osteochondritis dissecans (OCD). As a result, preoperative patient and family counseling regarding expected outcomes is difficult. The purpose of this study was to compare pre-to post-operative changes in PROMs amongst cohorts of patients with OCD that underwent one of three lesion-specific surgical treatments: 1) transarticular drilling for stable lesions, 2) drilling and fixation for unstable lesions 3) grafting for unsalvageable lesions. Methods: The electronic medical records of pediatric and adolescent patients with knee OCD, at a single institution between January 2017 and August 2019, were reviewed. Patients were categorized into one of three surgical groups, with initial determination confirmed at the time of surgery during diagnostic knee arthroscopy. Differences between groups were assessed with one-way analysis of variance (ANOVA). Results: Of the 78 patients included in this study, 49 (62.8%) were male with a mean age of 13.5 ± 2.2 years. There was no significant difference between the surgical groups for baseline HSS Pedi-FABS (P = 0.58) or PROMIS Mobility (P = 0.47). There were no significant differences in PROMIS PI scores at baseline (P = 0.32), at latest follow-up (P = 0.72), or in interval change from baseline to follow-up (P = 0.42), between the three surgical groups. Conclusion: Lesion-specific surgical management of OCD led to similar improvements in PROMIS PI at a minimum of one-year follow-up. These results may better allow surgeons to reassure patients and families that outcomes are similar when lesions are treated through a lesion-specific algorithm. Level of evidence: Level IV: Retrospective cohort study.

Establishing minimal detectable change thresholds for the international knee documentation committee and Kujala scores at one and two years after patellofemoral joint arthroplasty.

PURPOSE: To define the minimal detectable change (MDC) for the international knee documentation committee (IKDC) and Kujala scores one and two years after patellofemoral joint arthroplasty (PFA). METHODS: A distribution-based method (one-half the standard deviation of the mean difference between postoperative and preoperative outcome scores) was applied to establish MDC thresholds among 225 patients undergoing primary PFA at a single high-volume musculoskeletal-care center. Stability of change in MDC achievement was explored by quantifying the proportion of achievement at one- and two-year postoperative timepoints. Multivariable logistic regression analysis was performed to explore the association between sociodemographic and operative features on MDC achievement. RESULTS: MDC thresholds for the Kujala score were 10.3 (71.1% achievement) and 10.6 (70.4% achievement) at one- and two years, respectively. The MDC thresholds for the IKDC score were 11.2 (78.1% achievement) and 12.3 (69.0% achievement) at one- and two years, respectively. Predictors of achieving the MDC for the Kujala and IKDC scores at both time points were lower preoperative Kujala and IKDC scores, respectively. Preoperative thresholds of ≤ 24.1 and 7.6 for the Kujala and IKDC scores, respectively, were associated with a 90% MDC achievement probability. When preoperative thresholds approached 64.3 and 48.3 for the Kujala and IKDC, respectively, MDC achievement probability reduced to 50%. CONCLUSION: The MDC thresholds for the Kujala and IKDC scores two years after PFA were 10.6 and 12.3, respectively. Clinically significant health status changes were maintained overall, with a slight decrease in achievement rates between one and two years. MDC achievement was associated with disability at presentation, and several probability-based preoperative thresholds were defined. These findings may assist knee surgeons with patient selection and the decision to proceed with PFA by better understanding the patient-specific propensity for MDC achievement. LEVEL OF EVIDENCE: IV, retrospective case series.

Rare Fracture Knee Dislocation Treated with Ligament Repair and Novel Arcuate Fracture Repair Technique: A Case Report.

CASE: A 57-year-old man presented with a left knee dislocation after a motor vehicle collision. Clinical and imaging evaluation demonstrated disruption of the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), anterolateral ligament (ALL), and posterolateral corner (PLC). The patient underwent acute, single-stage arthroscopic primary ACL and PCL repair, with arcuate fracture fixation using a novel technique. At 4 years postoperatively, he continues to do well subjectively with minimal clinical laxity. CONCLUSION: Acute, single-stage arthroscopic primary ligamentous repair is a viable option for high-grade multiligamentous knee dislocations and may be combined with our novel technique for arcuate fracture fixation. LEVEL OF EVIDENCE: Level IV, Case Report.

Defining Minimal Clinically Important Difference After Open Hip Abductor Repair.

BACKGROUND: Open repair for gluteus medius and minimus tears is a common surgical treatment for patients with lateral hip pain associated with abductor tears; however, clinically meaningful outcomes have not been described after open surgical treatment. PURPOSE: To define the minimal clinically important difference (MCID) in patient-reported outcome measures (PROMs) in patients undergoing open gluteus medius or minimus repair, and to identify preoperative patient characteristics predictive of achieving MCID postoperatively. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A retrospective review of prospectively collected data from a consecutive series of patients undergoing open abductor repair between July 2010 and April 2019 was conducted. Perioperative patient data collected included patient characteristics and preoperative and postoperative modified Harris Hip Score (mHHS) and International Hip Outcome Tool (iHOT-33) score. Paired t tests were utilized to compare preoperative and postoperative PROMs and MCID was calculated for both PROMs. Multivariate logistical regression analysis was used to assess the association between preoperative variables and the likelihood for achieving MCID. RESULTS: A total of 47 patients were included in the study. The majority of patients were female (78.7%), with an average age of 63 ± 10.7 years. The average follow-up for both the mHHS and the iHOT-33 surveys was 37.8 ± 27.9 months (range, 10-102 months). Patients demonstrated statistically significant improvements on the mHHS and iHOT-33 postoperatively (P < .001 for both). The MCIDs of mHHS and iHOT-33 were calculated to be 9.9 and 14.3, respectively. Overall, 82.9% of patients achieved MCID for mHHS and 84.1% of patients achieved MCID for iHOT-33 postoperatively. Multivariate logistical analysis demonstrated younger patients were less likely to achieve MCID for both outcome measures. Four patients (8.5%) suffered postoperative complications after open repair. CONCLUSION: This study defined MCID for mHHS and iHOT-33 for patients undergoing open repair of hip abductor tears, with a large percentage of patients (>80%) achieving meaningful outcomes for both outcome measures. There was a low complication rate. Younger patients were less likely to achieve MCID compared with older patients.

Magnetic Resonance Imaging Findings of Core Muscle Injuries in High Level Athletes.

ABSTRACT: Core muscle injuries are common injuries in athletes involved in high speed side-to-side acceleration movements. The term core muscle injury encapsulates several different injuries that occur in the pelvic region that have similar presentations. Along with a good history and physical examination, magnetic resonance imaging (MRI) can be a helpful tool in the diagnostic process. Correct orientation and protocols are needed to show the correct anatomy with an MRI. Furthermore, to determine the exact etiology of the core muscle injury, it is important to know which structures are likely to be involved and be able to recognize the patterns of injury on imaging.

Juvenile Osteochondritis Dissecans of the Trochlea: A Cohort Study of 34 Trochlear Lesions Associated With Sporting Activities That Load the Patellofemoral Joint.

BACKGROUND: Juvenile osteochondritis dissecans (JOCD) lesions are rarely located in the trochlea and few studies have focused on the causes and outcomes of JOCD lesions in this part of the knee. The purpose of this study is to (1) evaluate the clinical characteristics and outcomes of patients who undergo surgery for JOCD in this unusual location as well as (2) assess the association between trochlear JOCD and participation in sporting activities that load the patellofemoral joint. METHODS: We conducted a retrospective cohort study of 34 trochlear JOCD lesions in 30 patients. Cases that involved traumatic cartilage shear or patella instability were excluded. Preoperative and postoperative magnetic resonance images and x-rays were evaluated and demographic data, sports played, comorbidities, surgical procedures, and clinical data were extracted from medical records. A case-control cohort of 102 femoral condyle lesions was used to assess the correlation between sports played and lesion location. RESULTS: The cohort comprised 34 consecutive trochlear JOCD lesions in 30 patients (26 males, 4 females). Average age at surgery was 13.8 years (9.3 to 18.0 y). In total, 27 (90%) patients were active, and of these active patients, soccer and basketball were the most common sports played. In the case-control comparison, the correlation between playing either basketball or soccer and the presence of a trochlear JOCD lesion was statistically significant (P=0.017). In total, 21 knees (62%) received operative treatment. Sixteen of the surgical patients underwent repair and fixation with bioabsorbable nails. The average length of clinical and radiographic follow-up was 21.1 months. All patients who underwent fixation showed radiographic and/or clinical indications of healing at most recent follow-up. Thirteen of the patients who underwent fixation were active, and all of these patients reported successful return to sports. Thirteen knees underwent nonoperative treatment, and the majority of these patients had limited follow-up. CONCLUSIONS: We report a significant association between pediatric athletes who play basketball and soccer and the development of trochlear JOCD, suggesting that repetitive loading of the patellofemoral joint may play a role in the development of JOCD lesions. Patients with trochlear JOCD lesions were likely to undergo surgery, and repair and fixation of the lesions produced good outcomes at short-term follow-up. LEVEL OF EVIDENCE: Level III-case-control study.

Long-term Evaluation of Meniscal Tissue Formation in 3-dimensional-Printed Scaffolds With Sequential Release of Connective Tissue Growth Factor and TGF-ß3 in an Ovine Model.

BACKGROUND: Artificial meniscal scaffolds are being developed to prevent development of osteoarthritis after meniscectomy. Previously, it was reported that 3-dimensional (3D) anatomic scaffolds loaded with connective tissue growth factor (CTGF) and transforming growth factor ß3 (TGF-ß3) achieved meniscal regeneration in an ovine model. This was a relatively short-term study (3 months postoperative), and outcome analyses did not include magnetic resonance imaging (MRI). PURPOSE: To evaluate long-term outcome of meniscal replacement with growth factor-laden poly-ε-caprolactone (PCL) scaffolds. STUDY DESIGN: Controlled laboratory study. METHODS: Anatomically shaped ovine meniscal scaffolds were fabricated from PCL with a 3D printer based on MRI data. Skeletally mature sheep (N = 34) were randomly allocated to 3 groups: scaffold without growth factor (0-µg group), scaffold with CTGF microspheres (µS) (5 µg) + TGF-ß3 µS (5 µg) (5-µg group), and scaffold with CTGF µS (10 µg) + TGF-ß3 µS (10 µg) (10-µg group). Unilateral medial meniscal replacement was performed. Animals were euthanized at 6 or 12 months. Regenerated meniscus, articular cartilage status, and synovial reaction were evaluated quantitatively with gross inspection, histology, and MRI. Kruskal-Wallis and Dunn tests were used to compare the 3 groups. RESULTS: Remnants of the PCL scaffold were evident in the 6-month specimens and were decreased but still present at 12 months in most animals. There were no significant differences among groups in gross inspection, histology, or MRI for either meniscal regeneration or articular cartilage protection. All experimental groups exhibited articular cartilage degeneration as compared with control (nonoperated). In terms of synovitis, there were no clear differences among groups, suggesting that growth factors did not increase inflammation and fibrosis. MRI revealed that meniscal extrusion was observed in most animals (82.7%). CONCLUSION: Previously, the combination of CTGF and TGF-ß3 was shown to stimulate mesenchymal stem cells into a fibrochondrocyte lineage. CTGF and TGF-ß3 did not aggravate synovitis, suggesting no adverse response to the combination of 3D-printed PCL scaffold combined with CTGF and TGF-ß3. Further work will be required to improve scaffold fixation to avoid meniscal extrusion. CLINICAL RELEVANCE: A significant advantage of this technique is the ability to print custom-fit scaffolds from MRI-generated templates. In addition, average-size menisci could be printed and available for off-the-shelf applications. Based on the 1-year duration of the study, the approach appears to be promising for meniscal regeneration in humans.

Postoperative Tendon Loading With Treadmill Running Delays Tendon-to-Bone Healing: Immunohistochemical Evaluation in a Murine Rotator Cuff Repair Model.

Mechanical stress has an important effect on tendon-to-bone healing. The purpose of the present study was to compare tendon-to-bone healing in animals exposed to either tendon unloading (botulinum toxin injection) or excessive loading (treadmill running) in a murine rotator cuff repair model. Forty-eight C57BL/6 mice underwent unilateral supraspinatus tendon detachment and repair. Mice in the unloaded group were injected with botulinum toxin to the supraspinatus muscle. The contralateral shoulder of the unloaded group was used as a control. Mice were euthanized at 1, 2, and 4 weeks after surgery and evaluated with hematoxylin-eosin and immunohistochemical (IHC) staining for Ihh, Gli1, Wnt3a, and ß-catenin. The positive staining area on IHC and the Modified Tendon Maturing Score were measured. The score of the unloaded group was significantly higher (better healing) than that of the treadmill group at 4 weeks. Ihh and the glioma-associated oncogene homolog 1 (Gli1) positive area in the unloaded group were significantly higher than those of the control group at 1 week. The peak time-points of the Ihh and Gli1 positive area was 1 week for the unloaded group and 2 weeks for the treadmill group. The Wnt3a positive area in the unloaded group was significantly higher than that of the control group at 2 weeks. The ß-catenin positive area in the unloaded group was significantly higher than that of the treadmill group and the control group at 1 week. Our data indicated that the unloaded group has superior tendon maturation compared to the treadmill running group. Excessive tendon loading may delay the tendon healing process by affecting the activity of Ihh and Wnt/ß-Catenin pathways. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1628-1637, 2019.

Medial patellofemoral ligament (MPFL) reconstruction technique using an epiphyseal femoral socket with fluoroscopic guidance helps avoid physeal injury in skeletally immature patients.

PURPOSE: The purpose of this study was to assess the physeal safety associated with the use of an epiphyseal femoral socket for paediatric medial patellofemoral ligament (MPFL) reconstruction. METHODS: Fifty-four knees in 49 skeletally immature patients underwent physeal-sparing MPFL reconstruction performed by 1 surgeon at a tertiary care academic medical centre from 2007 to 2016. A femoral socket distal to the femoral physis was used for graft fixation in all the patients. To assess physeal safety, all included patients either had post-operative MRIs of the operative knee or standing hip-to-ankle radiographs. Physeal safety was assessed on MRI, and the distance between the femoral socket relative to the physis was measured at both the aperture and the end of the socket. Development of lower limb angular deformities and/or limb length discrepancy (LLD) was evaluated using post-operative standing hip-to-ankle radiographs, patient records, and clinical assessments. RESULTS: The mean age at time of surgery was 13.3 ± 1.6 years. The median length of radiographic follow-up was 2.2 years (range 1.0-5.7 years). At most recent clinical follow-up, five patients (9.3%) had recurrent patellar instability, with three patients (5.6%) undergoing subsequent tibial tubercle osteotomy or revision MPFL reconstruction. There was no statistically significant difference in leg length between operated and non-operated extremities (n.s.). There was no statistically significant difference between non-operated and operated mMPTA (n.s.) and mLDFA (n.s.) measurements. On post-operative MRI, there was no evidence of physeal arrest. The median distance from the physis to the socket at the aperture and distal end of the femoral socket were 5.9 mm (range 1.9-12) and 7.1 mm (1.3-12.4), respectively. CONCLUSION: These results demonstrate that with fluoroscopic guidance, placing the femoral socket distal to the distal femoral physis is an effective method for avoiding physeal injury and subsequent growth disturbances in children with patellar instability. Clinically, this information is essential in optimal surgical management of these patients, as this technique allows for femoral fixation of the MPFL reconstruction graft within the epiphysis while also preserving normal growth. LEVEL OF EVIDENCE: Level IV-case series.

Decline in clinical scores at long-term follow-up of arthroscopically treated discoid lateral meniscus in children.

PURPOSE: The purpose of this study was to examine the long-term clinical outcomes of arthroscopic partial meniscectomy for the treatment of discoid lateral meniscus in children. METHODS: A previous study identified 34 consecutive patients that underwent arthroscopic meniscal saucerization by one of the two surgeons between 1997 and 2002. Patients were asked to complete several outcomes questionnaires and were given the opportunity to receive a knee exam performed by their treating surgeon. RESULTS: Of the 34 eligible patients, 21 agreed to participate. Seventeen patients (19 knees) had greater than 2-year follow-up, with an average follow-up of 11.0 years (range 3.4-16.6 years). Average age at the time of surgery was 9.3 years. Average IKDC, Kujala, and Lysholm scores at follow-up were 82.8 ± 28.9, 86.6 ± 15.2, and 83.7 ± 18.6, respectively. In addition, median Marx and Tegner scores were 5 (range 0-14) and 6 (range 3-8), respectively. Stratifying the Lysholm scores revealed outcomes that were 45.4% "excellent", 16.7% "good", 25.0% "fair", and 16.7% "poor". In total, 36.8% (7 of 19) of knees underwent at least one subsequent surgical procedure. There were no significant associations between outcome scores and discoid type, meniscal stability, location of instability, or age at time of surgery. CONCLUSIONS: The results of the current study suggest that clinical outcome scores decline over time in patients treated arthroscopically for symptomatic discoid meniscus. Compared to our previous study with 2-year follow-up, there is an increased incidence of knee pain and mechanical/functional limitations. The overall modest, long-term results of this study illustrate the need for improved operative treatments for symptomatic discoid meniscus in children to prevent progressive, long-term clinical decline in these patients.