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Background: Significant controversy surrounds ideal tunnel position for medial patellofemoral ligament (MPFL) reconstruction (MPFLR) in the pediatric setting. The start point for femoral tunnel positioning (the Schöttle point) relative to the distal medial femoral physis is not well defined. Previous studies provide conflicting data regarding position of the MPFL origin and the Schöttle point relative to the distal femoral physis. Hypothesis: The Schöttle point would be consistently distal to the distal medial femoral physis. Study Design: Descriptive laboratory study. Methods: The institutional picture archiving and communication system was queried for computed tomography (CT) imaging studies of pediatric knees. Data were imported to an open-source image computing platform. True lateral digitally reconstructed radiographs and 3-dimensional (3D) renderings were generated, and the Schöttle point was registered in 3D space. Then, 3D distance measurements were obtained from the Schöttle point to the distal medial femoral physis. Results: A total of 49 pediatric knee CT scans were included. Mean age was 13.0 ± 2.3 years. Mean minimum distance from the medial physis to the Schöttle point was 9.9 ± 3.0 mm (range, 3.4-16.1 mm). In 49 of 49 cases (100%), the Schöttle point was distal to the physis. Using a 6-mm reaming diameter would result in 3 of 49 (6%) femurs having violation of the distal medial femoral physis. Moving the start point 3 mm distally would result in 0 of 49 (0%) sustaining physeal injury. Conclusion/Clinical Relevance: The Schöttle point is consistently distal to the distal medial femoral physis. The mean minimum distance from the Schöttle point to the physis on the medial cortex is 9.9 mm. The Schöttle point provides a safe and reliable radiographic landmark for pediatric MPFLR, although reaming diameter should be considered.

PURPOSE OF REVIEW: To characterize current concepts in capsular repair and hip instability, and examine findings from biomechanical and clinical studies on hip capsular management strategies as they pertain to hip stability, patient outcomes, and hip arthroscopy failure. Further, we discuss the clinical evaluation and treatment of capsular deficiency. RECENT FINDINGS: There remains debate regarding the optimal capsular management strategies in hip arthroscopy, particularly concerning the necessity of routine capsular repair. A variety of capsulotomy techniques exist and may be used to access the hip joint. Additionally, a wide variety of techniques are employed to repair the hip capsule. Biomechanical evidence supports capsular closure restores hip joint stability to that of the intact, native state. Several clinical studies in both primary and revision hip arthroscopy settings have demonstrated improved pain and functional outcomes in patients who underwent capsular repair or capsular reconstruction. Studies have shown capsular repair may be especially important in patients with ligamentous laxity and hip dysplasia, and in competitive athletes. SUMMARY: Post-surgical hip instability secondary to capsular insufficiency is increasingly recognized as a cause of hip arthroscopy failure. Capsular closure restores native biomechanical stability to the hip joint, and several clinical studies report improved pain and functional outcomes following capsular repair or capsular reconstruction in both the primary and revision hip arthroscopy settings. There remains much to learn regarding capsular hip instability as it relates to optimal capsular management surgical technique, intra-operative capsular management decision-making, clinical diagnosis, and related advanced imaging findings.

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.

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.

Hip arthroscopy and femoral osteochondroplasty are commonly used in the treatment of femoroacetabular impingement (FAI). Determining the correct resection depth of the femoral head–neck cam lesion intraoperatively can be challenging. Both inadequate resection and over-resection may result in complications, underlying the importance of using a consistent and accurate technique when resecting and reshaping the proximal femur. Osseous resection to a depth of the subchondral cortical–cancellous bone margin in individuals with FAI has been shown to restore proximal femoral anatomy to within submillimeter differences when compared with control subjects without FAI. This bony boundary may be used as an intraoperative guide to consistently achieve appropriate resection depth. The sclerotic margin indicating the extent of the cam-type deformity can be evaluated with preoperative radiographs and recreated fluoroscopically, giving the surgeon a reliable intraoperative template. In addition, changes in clinical appearance during arthroscopy, particularly identification of the underlying trabecular structure at the cortical–cancellous border during resection, provides a visible, reliable intraoperative guide to resection depth.

Background: The anterior center-edge angle (ACEA) is used to quantify anterior coverage of the femoral head by the acetabulum. However, its measurement has not been evaluated in a manner consistent with routine use, and the precise 3-dimensional (3D) anatomic location where it measures coverage is not known. Purpose: To determine the effect of patient positioning on ACEA measurement reliability, magnitude, and 3D location. Study Design: Descriptive laboratory study. Methods: Included were 18 adults; 7 participants had cam morphology and femoroacetabular impingement syndrome, and 11 participants had no radiographic evidence of hip abnormalities and no history of hip pain or injuries. Ultimately, 3D femur and pelvis models were generated from computed tomography images. Radiographs were generated with the models in different degrees of pelvic rotation, tilt, and obliquity relative to the standard false-profile view. The ACEA was measured by 2 raters by selecting the location of the bone edge on each radiograph. Selections were projected onto the pelvis model and expressed as a clockface location on the acetabular rim. The clockface was mirrored on left hips to allow a direct comparison of locations between hips. Interrater and intrarater reliability were quantified via the intraclass correlation coefficient (ICC). The effect of position on ACEA measurements and clockface locations was determined via linear regression. Results: Intrarater and interrater reliability were excellent (ICC ≥0.97 for all). For every degree increase in rotation, tilt, and obliquity, the ACEA changed by +0.53°, +0.93°, and –0.04°, respectively. The mean clockface location (hour:minute:second) in the false-profile view was 2:09:32 ± 0:12:00 and changed by +0:02:08, –0:00:35, and –0:00:05 for every degree increase in rotation, tilt, and obliquity, respectively. Conclusion: ACEA measurements were reliable even with differences in patient positioning. Rotation and tilt were associated with notable changes in ACEA measurements. ACEA bone edge measurements mapped to the anterosuperior acetabular rim, typically in proximity to the anterior inferior iliac spine. Mapped location was most sensitive to rotation. Clinical Relevance: Pelvic rotation and tilt affected ACEA measurements, which could alter the clinical classification and treatment of borderline abnormalities. Rotation in particular must be well controlled during patient imaging to preserve measurement reliability and accuracy and to describe coverage from the intended 3D rim location.

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.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.Eighty patients were included. Bivariable regression showed an association between an increased distraction distance and female sex (β = 4.303, R = 0.561, P.001), as well as decreased anterior axial (β = -1.291, R = 0.365, P.001) and superior coronal (β = -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 (β = 3.175, P.001), as well as decreased superior coronal capsular thickness (β = -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).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 IV, case series.

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.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.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;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 IV, diagnostic case series.

To compare intraoperative hip joint distractibility between hips that previously underwent arthroscopic surgery and the contralateral hip with no history of surgical manipulation.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.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.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.III, case-control study.

To evaluate mid-term outcomes after medial patellofemoral ligament (MPFL) reconstruction with and without tape augmentation in the skeletally mature adolescent population.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.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%,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.IV, therapeutic case series.

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

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.

Case A 13-year-old boy sustained an acute, grade III medial collateral ligament (MCL) distal periosteal avulsion injury while playing noncontact football. Treatment consisted of diagnostic knee arthroscopy with open physeal-sparing MCL repair. At approximately 1-year follow-up, new development of genu valgum in the operative extremity was noted. After 8 months of nonoperative treatment with deformity progression, the patient underwent correction with proximal medial tibial hemiepiphysiodesis. Conclusion Although Cozen's phenomenon commonly occurs after a proximal metaphyseal tibial fracture in children aged 2 to 7 years, it can occur as a rare complication of MCL injury/repair and remains a possible outcome in skeletally immature patients.

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., Technique Video Video 1 Narrated key steps of arthroscopic reconstruction of the anterosuperior hip capsule in a right hip, as viewed from the anterolateral portal (superior view using a 70° scope). The anterolateral and modified anterior portals are established through the defect of the previous interportal capsulotomy. After defect identification and measurement, the dermal allograft is oversized by 5 mm in length and width. Sutures are placed circumferentially along the periphery of the capsular defect. In the absence of viable acetabular-sided capsule, suture anchors are placed to secure the graft. Sutures are brought out one by one through a 10-mm cannula and passed through the dermal allograft using a suture-passing device. A knot pusher is placed over one of the sutures in the graft and used to parachute the graft down through the cannula. The graft is secured in place by sequentially tying the sutures, beginning with those closest to the camera and working toward the medial side to facilitate visualization and suture management. Meticulous suture management is a key technical aspect of this procedure.

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).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.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.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.IV, case series.

To evaluate whether a narrow posterior joint space (2 mm) correlated with posterior joint cartilage degeneration in the hip preservation patient population.A retrospective chart review of 155 consecutive hip arthroscopy cases by a single surgeon (SKA) from March 2012 to February 2013 was performed. Patients were included in the study if they had an adequate perioperative false profile radiograph and clear intraoperative arthroscopic images of the posterior hip joint. The narrowest posterior joint space (NPJS) width and the directly posterior, posterosuperior, superior, and anterosuperior joint space widths were measured on the false profile radiograph. Femoral and acetabular cartilage of the posterior hip joint were graded according to the International Cartilage Repair Society (ICRS) classification system using arthroscopic images obtained at the time of surgery. The cartilage grades of patients with2 mm NPJS were compared with cartilage grades of patients with ≥2 mm NPJS.There was no difference in cartilage grading between patients with2 mm NPJS (19 patients) and those with ≥2 mm NPJS (81 patients) (P = .905). The mean age of patients with NPJS ≥2 mm and2 mm was 34.0 (median 31.2; interquartile range [IQR] 23.7, 42.9) and 38.7 (median 43.0; IQR 26.1, 50.9) respectively, and was not statistically different (P = .183). No correlation between cartilage grade and NPJS measurement was found (P = .374).In this predominantly cam-type femoroacetabular impingement patient cohort, our findings indicate there is no correlation between a2 mm posterior hip joint narrowing seen on false profile radiographs and posterior hip cartilage degeneration confirmed with arthroscopy. Although posterior arthritis can be visualized on a false profile radiograph, a posterior joint space measurement2 mm should not be interpreted as isolated posterior joint wear and should not be considered a hip arthroscopy contraindication.Level IV, case series.