The Role of the Hip Capsule in Restoring Stability in the Initial Phase of Hip Distraction: An In Vivo Analysis.

Background: The labral suction seal has been shown to provide the majority of resistance in the initial phase of hip distraction. However, the effect of an unrepaired interportal capsulotomy and capsular repair on the initial phase of hip distractive stability in vivo is not well understood. Purpose: To investigate the effect of capsular repair on the initial phase of distractive stability of hip joints in patients with femoroacetabular impingement (FAI) syndrome. Study Design: Controlled laboratory study. Methods: Patients undergoing primary hip arthroscopy for FAI between March and August 2020 were prospectively enrolled. Total joint space was measured on fluoroscopic images at the medial and lateral edges of the sourcil at 12.5-lb (5.7-kg) axial traction intervals (up to 100 lb [45.4 kg]) in 3 capsular states: (1) native capsule, (2) interportal capsulotomy, and (3) capsular repair. Distraction on anteroposterior radiographs was calculated as the difference between total joint space at each traction interval and baseline joint space at 0 lb, normalized to millimeters. The native, capsulotomy, and capsular repair states were compared using Wilcoxon signed-rank and McNemar tests. Results: Included were 36 hips in 35 patients. The median force required to distract ≥3 mm was 75 lb (34.0 kg; 95% CI, 70-80 lb [31.8-36.3 kg]) in both the native and capsular repair states (P = .629), which was significantly greater than the median force required to distract ≥3 mm in the capsulotomy state (50 lb [22.7 kg]; 95% CI, 45-55 lb [20.4-24.9 kg]) (P < .001). The most rapid rates of change in joint space were observed at the traction interval at which hips first achieved ≥3 mm of distraction (n = 33 hips; 92%). Conclusion: The traction force at which hips distracted ≥3 mm was 75 lb (34.0 kg) in both the native capsular and capsular repair states. Significantly less traction force (50 lb [22.7 kg]) distracted hips ≥3 mm in the capsulotomy state. Complete capsular closure after interportal capsulotomy resulted in restoration of initial distractive stability relative to the unrepaired capsulotomy state at time zero after primary hip arthroscopy. Clinical Relevance: This study provides surgeons with an improved understanding of the additional stability to the hip joint from capsular repair after hip arthroscopy for FAI syndrome.

Mid-term outcomes of temporary medial distal femoral hemiepiphysiodesis with and without medial patellofemoral ligament repair for recurrent patellar instability in skeletally immature patients with genu valgum.

Genu valgum contributes to patellar instability, though outcomes following temporary hemiepiphysiodesis via eight plating are less understood. The purpose of this study was to evaluate the outcomes and need for additional procedures following temporary hemiepiphysiodesis for the treatment of pediatric genu valgum and patellar instability, as well as evaluating the utility of a concurrent medial patellofemoral ligament (MPFL) repair. Patients who underwent medial distal femoral epiphysiodesis for the treatment of genu valgum and recurrent patellar instability were identified. Inclusion criteria were minimum 1-year follow-up and lack of concurrent ligamentous reconstruction. Patients were contacted to complete a questionnaire which included the International Knee Documentation Committee (IKDC) form and questions pertaining to knee function and patient satisfaction. Thirty-one patients aged 12.0 ± 1.9 years underwent 47 guided growth procedures and were included in final analysis. Seventeen knees (36%) required subsequent surgery for patellar instability. All patients requiring subsequent surgery were female, compared with 70% of patients not requiring subsequent surgery ( P  = 0.017). The MPFL repair group underwent fewer subsequent procedures to address instability, though this difference was NS (17 vs. 46%, P  = 0.318). Mean IKDC score at 5.3 years follow-up among 18 survey respondents was 78.6. Medial distal femoral hemiepiphysiodesis may partially address recurrent patellar instability in skeletally immature patients with genu valgum. Concurrent MPFL repair may minimize the need for subsequent procedures to address recurrent instability. While correcting alignment may be helpful, patients should be aware of the potential need for further patellar instability surgery. Level of evidence: IV, case series.

Characterization of Achilles Tendon Ruptures in Collegiate Women's Gymnastics.

Collegiate female gymnasts are at high risk of Achilles tendon injuries. Achilles tendon ruptures can negatively impact an athlete's ability to return to competitive sport. Understanding the natural history of Achilles tendon tears in collegiate female gymnasts is important in the development of preventive treatment. To expand our knowledge of the natural history of Achilles tendon ruptures among collegiate female gymnasts, a REDCap retrospective survey was emailed to athletic trainers on all 80 National Collegiate Athletic Association (NCAA) women's gymnastics teams. The survey gathered information regarding number of Achilles tendon injuries, pain prior to injuries, events and skills on which injuries occurred, and functional outcome after injuries among athletes competing in the 2013 to 2018 NCAA seasons. Forty-two of 80 (52.5%) programs responded to the survey. Seventy-one Achilles tendon ruptures were reported between 2013 and 2018. Among these, 46% had antecedent pain. Gymnasts sustained 95% of Achilles tendon ruptures while performing on floor exercise, with 98% of ruptures occurring during the take-off portion of a tumbling skill. Of the 61% of gymnasts who were able to return to competition, 59% were able to achieve the same level of function after injury. Achilles tendon ruptures in collegiate female gymnasts primarily occur during the take-off motion while tumbling on the floor exercise. Future studies should evaluate degenerative Achilles tendon changes in collegiate female gymnasts. A collaborative effort among gymnasts, coaches, judges, and medical experts is required to identify at-risk athletes and develop and implement injury prevention programs. [Orthopedics. 2023;46(4):205-210.].

Medial Patellofemoral Ligament Reconstruction in the Pediatric Population: Skeletal Immaturity Does Not Affect Functional Outcomes but Demonstrates Increased Rate of Subsequent Knee Injury.

Purpose: To evaluate short- to mid-term-outcomes, including instability rates, following medial patellofemoral ligament (MPFL) reconstruction in skeletally immature versus mature pediatric patients. Methods: Patients younger than age 18 with recurrent patellar instability who underwent primary allograft MPFL reconstruction by a single surgeon from 2013 to 2019 were identified. Skeletally immature patients underwent all-epiphyseal drilling and mature patients underwent metaphyseal drilling at the Schöttle's point. Patients 1 year from surgery were contacted to complete questionnaires, which included the International Knee Documentation Committee score. Further data included chart and imaging review. Significance was determined by P < .05. Results: Of 118 eligible patients, 88 completed questionnaires. There were 67 skeletally mature and 21 skeletally immature patients. The mature group was older (15 vs 13 years, P < .001), predominantly female (67 vs 43%, P = .046), and heavier (24.7 vs 18.9, P < .001). Trochlear dysplasia (P = .594), concomitant procedures (P = .336), graft choice (P = .274), and follow-up length (P = .107) did not differ, although mature patients more often underwent suture tape augmentation (68 vs 13%, P < .001). Immature patients had greater rates of ipsilateral injury (35 vs 16%, P = .043); redislocation rate did not differ (9 vs 3%, P = .225). Mature patients were more likely to respond "definitely yes or probably yes" when asked if they would undergo the same care if needed (96 vs 76%, P = .007). At minimum 2-year follow-up, subsequent ipsilateral injury rates did not differ, although willingness to undergo the same care remained significant (95 vs 69%, P = .010). In a multivariable elimination logistic regression model, skeletal maturity was the only variable associated with subsequent ipsilateral injury (P = .049). Conclusions: Pediatric patients undergoing MPFL reconstruction have good and comparable outcomes regardless of skeletal maturity. However, younger age and lack of tape augmentation in skeletally immature patients may predispose them to subsequent injury. Level of Evidence: III, case-control study.

Female Patients and Decreased Hip Capsular Thickness on Magnetic Resonance Imaging Associated With Increased Axial Distraction Distance on Examination Under Anesthesia: An In Vivo Study.

PURPOSE: To investigate the relation of hip capsular thickness as measured on preoperative magnetic resonance imaging (MRI) and intraoperative hip joint axial distraction distance on an examination under anesthesia. METHODS: A retrospective review of primary arthroscopic hip procedures performed between November 2018 and June 2021 was conducted. The inclusion criteria included a diagnosis of femoroacetabular impingement syndrome and preoperative radiographic imaging and MRI. Fluoroscopic images were obtained at 0 lb and 100 lb of axial traction force. Total distraction distance was calculated by comparing the initial joint space with the total joint space at 100 lb. Hip capsular thickness was measured on MRI. Analysis was conducted using multiple linear regression, independent-samples t tests, and Mann-Whitney U tests. RESULTS: Eighty patients were included. Bivariable regression showed an association between an increased distraction distance and female sex (ß = 4.303, R = 0.561, P < .001), as well as decreased anterior axial (ß = -1.291, R = 0.365, P < .001) and superior coronal (ß = -1.433, R = 0.501, P < .001) capsular thickness. Multivariable regression (R = 0.645) showed an association between an increased distraction distance and female sex (ß = 3.175, P < .001), as well as decreased superior coronal capsular thickness (ß = -0.764, P = .022). Independent-samples t tests showed that female patients had significantly decreased superior coronal capsular thickness (2.92 ± 1.14 mm vs 3.99 ± 1.15 mm, P < .001). CONCLUSIONS: Female sex and decreased hip capsular thickness in the superior aspect of the coronal plane on magnetic resonance scans were found to be predictors of increased hip joint axial distraction distance on examination under anesthesia prior to hip arthroscopy, with anterior axial capsular thickness being a moderate predictor. Poor predictors of distraction distance were posterior axial and inferior coronal capsular thickness, age, body mass index, and lateral center-edge angle. Female patients were also found to have thinner hip capsules in the superior region, which may explain the association between female patients and increased distraction. These findings further characterize the relation between capsular thickness and hip laxity. LEVEL OF EVIDENCE: Level IV, case series.

Tape Augmentation Does Not Affect Mid-Term Outcomes of Medial Patellofemoral Ligament Reconstruction in Skeletally Mature Adolescent Patients.

Purpose: To evaluate mid-term outcomes after medial patellofemoral ligament (MPFL) reconstruction with and without tape augmentation in the skeletally mature adolescent population. Methods: All patients under age 18 with recurrent patellar instability treated with surgery at a single institution by a single surgeon from January 2013 through June 2017 were identified by current procedural terminology codes. Inclusion criteria were (1) primary MPFL reconstruction, (2) minimum 3 years' follow-up, (3) skeletal maturity. Exclusion criteria were (1) bilateral MPFL reconstruction using different techniques on each knee, (2) prior surgery for patellar instability. Chart and imaging review was completed. Patients were contacted to complete a questionnaire, which included the International Knee Documentation Committee (IKDC) form. Results: Fifty-one of 92 eligible patients completed questionnaires. Two patients were excluded. Twenty patients underwent 23 non-augmented MPFL reconstructions; 29 patients underwent 33 augmented MPFL reconstructions. Group demographics were similar. At 4.9 ± 1.2 years follow-up, mean IKDC scores were 77.4 and 79.4 in the nonaugmentation and augmentation groups, respectively. Significantly fewer patients in the augmentation group experienced further injury to their ipsilateral knee compared to the non-augmentation group (6% vs 30%, P = .019). Fewer knees in the augmentation group developed recurrent subjective instability or dislocation after initial surgery requiring surgical correction compared to knees in the nonaugmentation group, although this difference was not significant (6% vs 17%, P = 0.181). Overall patient-reported outcomes were similar between the 2 groups. Conclusions: There were no significant differences in patient-reported outcomes after MPFL reconstruction with or without tape augmentation. Tape augmentation significantly decreased the risk of subsequent ipsilateral knee injuries, although it did not show a significant difference in recurrent dislocations. Level of Evidence: IV, therapeutic case series.

Magnetic Resonance Arthrogram Improves Visualization of Hip Capsular Defects in Patients Undergoing Previous Hip Arthroscopy.

Purpose: To compare magnetic resonance imaging (MRI) with magnetic resonance arthrogram (MRA) in the identification of hip capsular defects in patients who previously underwent hip arthroscopy. Methods: Patients who underwent revision hip arthroscopy for capsular insufficiency by a single surgeon between March 2014 and December 2019 were identified by Current Procedural Terminology code. Patients with arthroscopically confirmed capsular defects treated surgically who underwent both MRI and MRA between their primary and revision surgeries were identified. Imaging studies were blinded, randomized, and distributed to two fellowship-trained musculoskeletal radiologists. Radiologists evaluated 14 components of different anatomic structures, including the presence of capsular defect and defect grading, over 2 months, with a 2-week washout period between 4 sets of reads to obtain 2 complete reads from each radiologist. Data were analyzed in R version 4.0.2. Results: Two hundred thirty patients underwent revision hip arthroscopy between March 2014 and December 2019. Twelve patients had both an MRI and an MRA of the operated hip performed between their primary and revision surgeries. Time between primary and revision hip arthroscopy was 2.0 ± 1.5 years (R: .3-6.3). Time between MRI and MRA was .6 ± .6 years (R: .0-1.6). Sensitivity for detecting hip capsular defects was significantly higher for MRA than for MRI (87.5%, 95% CI: [68,96] vs 50%, 95% CI: [31,69], respectively; P = .008). Conclusions: This retrospective review demonstrates that MRA has higher sensitivity than MRI in detecting surgically confirmed capsular defects. MRA may be more helpful in identifying capsular defects in patients presenting with hip instability symptoms who have had a previous hip arthroscopy. Level of Evidence: Level IV, diagnostic case series.

Previous Arthroscopic Hip Surgery Increases Axial Distractibility Compared to the Native Contralateral Hip and May Suggest Instability.

PURPOSE: To compare intraoperative hip joint distractibility between hips that previously underwent arthroscopic surgery and the contralateral hip with no history of surgical manipulation. METHODS: Patients undergoing revision hip arthroscopy between April 2019 and December 2020, who previously underwent arthroscopic hip surgery for femoroacetabular impingement syndrome, were prospectively enrolled. Exclusion criteria were any contralateral hip surgery. Before instrumentation, fluoroscopic images of both hips were obtained at 25 lbs traction intervals up to 100 lbs. Total joint space was measured at each traction interval. Distraction was calculated as the difference between the baseline joint space and the total joint space at each subsequent traction interval. Wilcoxon signed ranks tests and McNemar tests were used to compare distraction between revision and native contralateral hips. RESULTS: Forty-seven patients were included. Mean distraction of operative hips was significantly greater than mean distraction of nonoperative hips at traction intervals of 50 lbs (2.13 vs 1.04 mm, P = .002), 75 lbs (6.39 vs 3.70 mm, P < .001), and 100 lbs (8.24 vs 5.39, P < .001). Mean total joint space of operative hips was significantly greater than mean total joint space of nonoperative hips at traction intervals of 50 lbs (6.60 vs 5.39 mm, P < .001), 75 lbs (10.86 vs 8.05 mm, P < .001), and 100 lbs (12.73 vs 9.73, P < .001). A greater percentage of operative hips achieved all distraction thresholds, in 2-mm intervals up to 10-mm, at each traction interval. CONCLUSIONS: In the majority of patients undergoing revision hip arthroscopy, previous arthroscopic hip surgery increases axial distractibility of the hip joint compared with the native contralateral hip at axial traction forces of 50-100 lbs. Increased axial distractibility following hip arthroscopy may be suggestive of hip instability and can be assessed on a stress examination with the patient under anesthesia. LEVEL OF EVIDENCE: III, case-control study.

Postoperative Pain Medication Utilization in Pediatric Patients Undergoing Sports Orthopaedic Surgery: Characterizing Patient Usage Patterns and Opioid Retention.

INTRODUCTION: Opioid overprescribing is a problem in orthopaedic surgery, with many patients having leftover opioid medications after surgery. The purpose of our study was to capture utilization patterns of opioids in pediatric patients undergoing orthopaedic sports medicine surgery, in addition to evaluating patient practices surrounding unutilized opioid medication. Our hypothesis was that there would be low utilization of opioids in this patient population and would in turn contribute to notable overprescribing of opioids and opioid retention in this population. METHODS: Pediatric patients undergoing orthopaedic surgery for knee and hip pathology were prospectively enrolled. A survey was administered 14 days postoperatively, with questions centered on the patient-reported number of opioids prescribed, number of opioids used, number of days opioids were used, and incidences of leftover opioid medication and disposal of leftover medication. The magnitude of opioid overprescribing was calculated using the reported prescribed and reported used number of opioid pills. Linear regression was used to examine associations between opioids and NSAIDs prescribed. RESULTS: One hundred fourteen patients reported a mean prescription of 12.0 ± 5.0 pills, with utilization of 4.4 ± 6.1 pills over 2.7 ± 5.1 days. Patients were prescribed 2.73 times the number of opioid pills required on average. One hundred patients (87.7%) reported having unused opioid medication after their surgery, with 71 (71.0%) reporting opioid retention. Regression results showed an association with opioids used and prescribed opioid amount (ß = 0.582, R = 0.471, P < 0.001). DISCUSSION: Overall, our study results help characterize the utilization patterns of opioid medications in the postsurgical pediatric sports orthopaedic population and suggest that orthopaedic surgeons may be able to provide smaller quantities of opioid pills for analgesia than is typically prescribed, which in turn may help reduce the amount of prescription opioid medications present in the community. LEVEL OF EVIDENCE: Level IV.

Tibial Spine Repair in the Pediatric Population: Outcomes and Subsequent Injury Rates.

PURPOSE: To evaluate short- to mid-term outcomes after arthroscopic operative fixation of tibial spine fractures in pediatric patients, to determine the incidence of further ipsilateral and contralateral knee injuries, and to describe associated meniscal pathology and intraoperative findings at the time of tibial spine repair. METHODS: All patients under age 18 with a tibial spine fracture treated arthroscopically at 1 institution by 2 surgeons from 2008 through 2019 were identified by Current Procedural Terminology codes. Patients at least 1 year from their date of surgery were contacted to complete a questionnaire, which included the International Knee Documentation Committee (IKDC) form. Questions pertained to knee function, pain, and further injury or surgery on either knee. Patient charts, preoperative imaging, and operative reports were reviewed to determine demographic information, tibial spine fracture type, concomitant injuries, and intraoperative details. RESULTS: Sixty-six of 97 eligible patients (68%) completed questionnaires. Average age at initial surgery was 10.7 years (range, 4-17). Mean follow-up was 5.8 years (range, 1.0-11.9). Average IKDC score at follow-up was 91.4 (range, 62.1-100). Patients reported their knee as 92% of "normal" (range, 40-100). Thirty-five (53%) currently participate in sport; 6 (9%) remain limited because of instability and residual pain. Regarding pain on a visual analog scale, 94%, 95%, and 83% of patients reported less than a 3 at rest, with daily activity, and with sport, respectively. Seven patients (11%) had subsequent ACL rupture. Six patients (9%) underwent ACL reconstruction 3.1 years (range, 0.9-7) after initial repair. Fourteen patients (21%) required at least 1 additional procedure. Regarding the contralateral knee, there were no ACL or tibial spine injuries. Sixty-one (92%) patients were both satisfied and would definitely undergo the procedure again. CONCLUSIONS: Although many pediatric patients demonstrate excellent results after tibial spine repair at mean 5.8 years follow-up, 10.6% sustained an ipsilateral ACL rupture, and 21% required an additional procedure. No patient had a contralateral tibial spine or ACL injury. This is helpful when counseling patients regarding injury risk when returning to activity after tibial spine repair. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Chondrosarcoma Arising in Synovial Chondromatosis of the Hip: A Case Report.

CASE: Synovial chondromatosis (SC) is a rare condition involving the proliferation of cartilage within the synovial membrane secondary to subsynovial connective tissue metaplasia. Malignant transformation to chondrosarcoma is rare. We cite a case of SC of the hip refractory to arthroscopic debridement, found to have secondary chondrosarcoma on aborted total hip arthroplasty, in which curative treatment was ultimately obtained with external hemipelvectomy. CONCLUSION: SC has the potential to undergo malignant transformation to chondrosarcoma. The consequences of not recognizing such transformation can significantly impact patient outcomes and limit options for local control surgery and limb salvage.

Capsular Repair During Hip Arthroscopy Demonstrates Restoration of Axial Distraction Resistance in an in Vivo Intraoperative Testing Model.

BACKGROUND: Cadaveric models demonstrate that failure of hip capsular repair is dependent on the robustness of the repair construct. In vivo data on capsular repair construct efficacy are limited. We investigated the effect of a figure-of-8 capsular repair on hip distraction resistance relative to native and post-capsulotomy states. We hypothesized that an unrepaired capsulotomy would demonstrate increased axial distraction compared with the native state and that capsular repair would restore distraction resistance to native levels. METHODS: Patients undergoing primary hip arthroscopy by a single surgeon were prospectively enrolled between March 2020 and June 2020. Prior to any instrumentation, fluoroscopic images of the operative hip were obtained at 12.5-lbs (5.7-kg) traction intervals, up to 100 lbs (45.4 kg). Anterolateral, modified anterior, and distal anterolateral portals were established. Following interportal capsulotomy, labral repair, and osteochondroplasty, fluoroscopic images were reobtained at each traction interval. Capsular repair was performed with use of a figure-of-8 suture configuration. Traction was reapplied and fluoroscopic images were again obtained. Joint distraction distance was measured at each traction interval for all 3 capsular states. Anteroposterior pelvic radiographs were utilized to scale fluoroscopic images to obtain joint space measurements in millimeters. RESULTS: A total of 31 hips in 31 patients were included. Capsulotomy resulted in significant increases in distraction distance from 25 (11.3 kg) to 100 lbs of traction compared with both native and capsular repair states (all comparisons, p ≤ 0.017). Capsular repair yielded a significantly greater distraction distance compared with the native state at 37.5 lbs (17.0 kg; 5.49 versus 4.98 mm, respectively; p = 0.012) and 50 lbs (22.7 kg; 6.08 versus 5.35 mm; p < 0.001). The mean difference in distraction distance between native and capsular repair states from 25 to 100 lbs of traction was 0.01 mm. CONCLUSIONS: This in vivo model demonstrates that an unrepaired interportal capsulotomy significantly increases axial distraction distance compared with the native, intact hip capsule. Performing a complete capsular closure reconstitutes resistance to axial distraction intraoperatively. Future research should evaluate the in vivo effects and associated clinical outcomes of other published capsular repair techniques and assess the durability of capsular repairs over time.

Arthroscopic Hip Capsule Reconstruction for Anterior Hip Capsule Insufficiency in the Revision Setting.

Iatrogenic hip instability is increasingly recognized as a cause of persistent pain and disability after hip arthroscopy. Many authors currently advocate capsular repair to reduce postoperative instability. However, anatomic deficiencies in the anterosuperior capsule can prevent a functional capsular repair, particularly in the revision setting. Capsular reconstruction has been shown to restore biomechanical stabilization in cadaveric models and improve short-term patient outcomes in patients with primary hip arthroscopy failure. Arthroscopic hip capsular reconstruction is technically challenging, largely owing to complex suture management and difficulties with graft placement and sizing. This article describes the capsular reconstruction technique, detailing the technical aspects of anterosuperior capsular defect identification; capsular preparation; suture management; and dermal allograft sizing, preparation, and positioning.

Overgrowth After Pediatric Tibial Spine Repair with Symptomatic Leg Length Discrepancy: A Case Report.

CASE: A 12-year-old girl sustained a right-sided tibial spine fracture while jumping on a trampoline. Postoperative course was complicated initially by arthrofibrosis requiring manipulation under anesthesia and subsequent leg length discrepancy attributed to posttraumatic overgrowth necessitating femoral epiphysiodesis. Ten years after initial injury, she reported her knee to be 63% of normal and an International Knee Documentation Committee score of 63.2. Symptomatic overgrowth requiring epiphysiodesis after tibial spine repair has not been previously reported to our knowledge. CONCLUSION: Tibial spine fixation, although previously associated with growth arrest because of physeal damage, may also result in symptomatic limb overgrowth.

Ischial osteoid osteoma: A cause of persistent hip pain in an adolescent patient with bilateral femoroacetabular impingement.

A 15-year-old boy presented with left-sided hip pain and imaging consistent with the diagnosis of femoroacetabular impingement. Following hip arthroscopy, which included an osteochondroplasty, labral repair, and capsular repair, the patient's anterior hip pain improved. However, his deep aching hip pain persisted until an ischial osteoid osteoma was identified and treated with radiofrequency ablation. At 3 years follow-up, the patient reports high satisfaction and minimal pain. We present this case to illustrate the importance of considering all potential causes of persistent hip pain following hip arthroscopy, including benign bone tumors which may be difficult to visualize on plain radiographs.

Joint Venting Prior to Hip Distraction Minimizes Traction Forces During Hip Arthroscopy.

PURPOSE: This study evaluates the effect of venting on distraction of the hip during arthroscopy on a post-free traction table for fixed traction forces ranging from 0 to 100 pounds (lbs). METHODS: Patients underwent surgery by the senior author (S.K.A.) between November 2018 and July 2019. Inclusion criteria were primary hip arthroscopy requiring central compartment access. Patients were positioned in 10-15° Trendelenburg on a post-free traction table. Prior to instrumentation, fluoroscopic images of the operated hip joint were taken at 25-lb intervals from 0 to 100 lbs of axial traction. Traction was released for 15 minutes. Venting with 20 mL of air was performed and fluoroscopic images were repeated at all traction intervals. Joint displacement was measured at all intervals. An unvented control group underwent the same axial traction protocol for comparison. RESULTS: Sixty-one consecutive patients underwent study protocol. Fifty-eight hips in 57 patients were included. Thirty-two (55.2%) were female; mean age was 31 ± 13 years and mean body mass index was 25.7 ± 6.2. Paired samples analysis demonstrated mean differences in distraction distance prior to and after venting of 0.27, 2.60, 4.09, 4.54, and 2.31 mm at 0, 25, 50, 75, and 100 lbs of traction, which were significant (P < .001) at all traction intervals. Significantly more vented hips distracted at least 10 mm at 25-100 lbs traction (P ≤ .001). An unvented control group showed no significant differences between the first and second traction application. CONCLUSIONS: Venting prior to applying traction on a post-free traction table increases the distraction distance achieved for a given traction force at multiple levels of traction in comparison to the pre-vented state. Our results suggest venting the hip joint prior to the application of traction may serve to reduce the maximal amount of traction required to safely instrument the hip arthroscopically. LEVEL OF EVIDENCE: IV, case series.

Three-Dimensional Magnetic Resonance Arthrography of Post-Arthroscopy Hip Instability Demonstrates Increased Effective Intracapsular Volume and Anterosuperior Capsular Changes.

PURPOSE: To quantify the magnetic resonance arthrography (MRA) capsular morphologic findings associated with postarthroscopy hip instability. METHODS: Among patients with clinically significant iatrogenic hip instability at a single center, patients with preindex and postindex surgery MRAs were identified. These MRAs were compared regarding effective intracapsular volume calculated by semi-automated 3-dimensional pixel intensity region segmentation, 2-dimensional anterior proximal intracapsular area in the femoral neck axial plane reconstruction, maximal anterior fluid pocket depth, capsule retraction distance, and capsular instability grade. Morphological measurements were conducted using Horos image processing software. Paired t-test, paired Wilcoxon signed rank test, and the McNemar test were used for identifying statistical significance. RESULTS: In 42 patients, mean effective intracapsular volume was significantly greater in the postindex surgery MRAs (19.44 cm3 vs 17.26 cm3; P = .006). Proximal anterosuperior (12-3 o'clock) intracapsular area was also significantly greater after index surgery (2.84 cm2 vs 1.43 cm2; P < .001. Proximal anteroinferior (3-6 o'clock) intracapsular area (1.34 cm2 vs 0.97 cm2; P = .002), capsule deficiency grade (P < .001), anterior capsule retraction distance (4.83 mm vs 0.34 mm; P < .001), and maximum anterior fluid depth (8.33 mm vs 4.90 mm; P <.001) were also significantly increased after index surgery. CONCLUSION: In comparison to the preoperative state, iatrogenic hip instability is associated with MRA findings that include increases in total effective intracapsular volume, proximal anterosuperior and anteroinferior intracapsular cross-sectional area, maximum proximal anterosuperior fluid depth, and capsule retraction distance. LEVEL OF EVIDENCE: Level IV, diagnostic case series.

HRAS-driven cancer cells are vulnerable to TRPML1 inhibition.

By serving as intermediaries between cellular metabolism and the bioenergetic demands of proliferation, endolysosomes allow cancer cells to thrive under normally detrimental conditions. Here, we show that an endolysosomal TRP channel, TRPML1, is necessary for the proliferation of cancer cells that bear activating mutations in HRAS Expression of MCOLN1, which encodes TRPML1, is significantly elevated in HRAS-positive tumors and inversely correlated with patient prognosis. Concordantly, MCOLN1 knockdown or TRPML1 inhibition selectively reduces the proliferation of cancer cells that express oncogenic, but not wild-type, HRAS Mechanistically, TRPML1 maintains oncogenic HRAS in signaling-competent nanoclusters at the plasma membrane by mediating cholesterol de-esterification and transport. TRPML1 inhibition disrupts the distribution and levels of cholesterol and thereby attenuates HRAS nanoclustering and plasma membrane abundance, ERK phosphorylation, and cell proliferation. These findings reveal a selective vulnerability of HRAS-driven cancers to TRPML1 inhibition, which may be leveraged as an actionable therapeutic strategy.