Tibial Tubercle Osteotomy With and Without Medial Patellofemoral Ligament Reconstruction in Adolescent Patients Leads to Decrease in Patellar Height and Patella Tendon Length.

OBJECTIVE: Patellar height changes after tibial tubercle osteotomy (TTO) have not yet been described. We aimed to evaluate whether TTO ± medial patellofemoral ligament reconstruction (MPFL-R) influences patellar height and tendon length, hypothesizing that TTO would decrease patellar height and tendon length. METHODS: A retrospective review was performed of skeletally mature adolescents (<18 y) receiving primary anteromedialization or medialization TTO ± MPFL-R. Patients with at least 6 months of radiographic follow-up were included in the study. Pre and postoperative patellar heights were assessed on lateral, weight-bearing, and flexion (30 to 70 degrees) radiographs using the Blackburne-Peel Index (BPI), Caton-Deschamps Index (CDI), and Insall-Salvati Ratio (ISR). Subgroup analyses were performed to compare patellar height changes in patients with preoperative patella alta, norma, and baja, as well as between patients undergoing medialization and anteromedialization TTO. Data were analyzed for normality using a Shapiro-Wilk test, and paired-sample t tests were performed. RESULTS: Forty-nine knees were included (mean age: 15 y; range: 12 to 17). A significant decrease in mean patellar height after TTO ± MPFL-R was observed across all measures: BPI (0.12, P = 0.000783), CDI (0.08, P = 0.01062), and ISR (0.15, P = 0.00000075). Patellar tendon length decreased by 2.26 mm ( P = 0.001272). Subgroup analyses demonstrated a decrease in mean patellar height across all 3 measurements ( P < 0.001; BPI, CDI, and ISR) for patients with preoperative patella alta but not patella norma or baja. Additional subgroup analysis showed a patellar height decrease using BPI (0.15, P = 0.004583) and ISR (0.14, P = 0.0002806) for patients receiving medialization TTO but not anteromedialization. The anteromedialization cohort did not demonstrate patellar height change using BPI and CDI; ISR demonstrated a decrease (0.10, P = 0.00917). CONCLUSIONS: Mean patellar height and tendon length decreases after TTO ± MPFL-R in skeletally mature, adolescent patients. Subgroup analyses suggest these changes occur in patients with preoperative patella alta and/or patients who undergo medialization TTO. These data suggest that some distalization in patellar positioning may be achieved without formal distalization osteotomy.

Dysplastic Hips Have Decreased Iliofemoral Ligament Thickness on Coronal Sequences in Magnetic Resonance Imaging: A Matched Cohort Analysis.

PURPOSE: To characterize hip capsule thickness on advanced imaging in patients with and without hip dysplasia and to also evaluate differences in capsular thickness between borderline and true dysplastic patients. METHODS: Patients evaluated by the senior author for concerns of hip pathology from June 2020 to June 2021 were queried and images reviewed to determine dysplasia status by lateral center edge angle (LCEA) ≤ 25 degrees. A group of non-dysplastic patients was identified and matched for age, sex, and body mass index (BMI). Hip capsular thickness was quantified using MRI. A sub-analysis was conducted to compare true dysplastic patients (LCEA < 20°) to borderline dysplastic patients (LCEAs between 20 - 25°). Analysis included independent samples t-tests, Chi-square tests, and multivariable regression. RESULTS: Eighty total patients were included, with a mean age of 31.8 ± 11.7 years, a mean BMI of 26.6 ± 6.5 points, and 70% (56) female patients. Dysplastic patients had a mean LCEA of 19.8 ± 4.3 degrees. Dysplastic individuals had decreased capsular thickness compared to their non-dysplastic controls (2.75 ± 0.96 vs 3.52 ± 1.22 mm, p = 0.003). Multivariable regression showed decreased capsular thickness associated with decreased LCEAs (ß = 2.804, R = 0.432, p<0.001) and dysplasia (ß = -0.709, R2 = 0.056, p = 0.004). Results of a sub-analysis of the dysplastic group examining differences between accepted definitions of borderline dysplasia and true dysplasia showed no significant differences in capsular thickness between the two groups (p = 0.379). CONCLUSIONS: Patients with hip dysplasia were found to have thinner iliofemoral ligaments in the coronal plane on magnetic resonance imaging on magnetic resonance imaging. Further investigation is needed to evaluate any potential implications with hip instability given the thinner hip capsule demonstrated in this study.

Physeal Location on the Distal Femoral Cortical Surface Is Consistently Proximal to Apparent Location on the Perfect Lateral Radiograph: A 3-Dimensional Digitally Reconstructed Radiograph Study.

INTRODUCTION: The perfect knee lateral radiograph visualizes anatomic landmarks on the distal femur for clinical and scientific purposes. However, radiographic imaging is a two-dimensional (2D) representation of a three-dimensional (3D) physis. The aim of this study was to characterize the perceived radiographic projection of the femoral physis using perfect lateral digitally reconstructed radiographs (DRRs) and to evaluate discrepancies from this projection to the physis at the lateral and medial cortices. METHODS: Pediatric patients from a cohort of CT scans were analyzed. Inclusion criteria were an open physis; exclusion criteria were any implant or pathology affecting the physis. CT scans were imported into 3D imaging software and transformed into lateral DRRs and 3D renderings of the femur. The physis was divided into four equal segments, with fiducial markers placed at the "anterior," "midpoint," and "posterior" points. Lines extended from these points in the lateral and medial direction. The vertical distance from these lines, representing the radiographic projection of the physis, was measured relative to the physis at the lateral and medial cortex of the femur on coronal CT slices. RESULTS: Thirty-one patients were included. On the perfect lateral radiograph DRR, the physis on the medial cortex was located proximal to the visualized physis by 6.64 ± 1.74 mm, 11.95 ± 1.67 mm, and 14.30 ± 1.75 mm at the anterior (25%), midpoint (50%), and posterior (75%) locations, respectively. On the lateral side, the physis on the lateral cortex was proximal to the visualized physis by 2.19 ± 1.13 mm, 3.71 ± 1.19 mm, and 6.74 ± 1.25 mm at the anterior, midpoint, and posterior locations, respectively. DISCUSSION: In this cohort of pediatric patients, the location of the cortical physis was, in all areas measured, proximal to the projection of the visualized physis as seen on the perfect knee lateral DRR. The distance from radiographic physis to cortical physis was greater at the medial cortex compared with the lateral cortex. STUDY DESIGN: Descriptive laboratory study. LEVEL OF EVIDENCE: III, observational radiographic anatomic study.

Common radiographic indices used to measure patellar height do not consistently identify patella alta and lack interchangeability between measurements.

PURPOSE: Abnormal patellar height has been identified as a source of aberrant mechanical functioning within the patellofemoral joint. The purpose of this study is to examine the statistical agreement among three commonly used classification methods: Blackburne-Peel (BPI), Caton-Deschamps (CDI) and Insall-Salvati (ISR), by evaluating (1) the rates of patella alta identification and (2) the ability for one index to predict another. METHODS: One hundred lateral knee radiographs were evaluated using BPI, CDI and ISR to classify each knee as patella normal, patella alta or patella baja. Linear regression analysis was performed to evaluate the relationship between each index. Conversion equations were then derived using the reported linear regression best-fit line, comparing each pair of indices. RESULTS: Patella alta was identified in 15 knees using BPI, 15 using CDI and 25 using ISR. A total of seven knees were classified as patella alta by all BPI, CDI and ISR. Statistical analysis revealed significant correlation (p ≤ 0.001) among BPI and CDI (R2 = 0.706), BPI and ISR (R2 = 0.328) and CDI and ISR (R2 = 0.288). Wilcoxon Signed-Rank test between the three indices revealed no significant difference between the means of converted and original indices. CONCLUSION: Despite their significant correlations and adequate reproducibility, variability between common patellar height indices render predictions and conversions between BPI, CDI and ISR inequivalent. Users of these indices must be aware of their incongruent properties when considering application to patients in the clinical setting. Furthermore, it remains unclear which patellar height measurement technique is the correct index to use in a given knee. This study highlights the need for further investigation to create a reliable and standardised method for identifying patella height. LEVEL OF EVIDENCE: Level IV.

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.

Magnetic Resonance Imaging and Magnetic Resonance Arthrography Are Both Reliable and Similar When Measuring Hip Capsule Thickness in Patients With Femoroacetabular Impingement Syndrome.

Purpose: To propose an accurate method of measuring hip capsular thickness in patients with femoroacetabular impingement syndrome and to compare the reliability of these measurements between magnetic resonance imaging (MRI) and magnetic resonance arthrography (MRA). Methods: A previously established database of patients with femoroacetabular impingement syndrome (FAIS) was used to identify candidates with preoperative MRI or MRA from November 2018 to June 2021. Two reviewers independently examined preoperative imaging for 85 patients. Capsular thickness was measured in 12 standardized locations. Intraclass correlation coefficients (ICCs) were calculated using an absolute-agreement, 2-way random-effects model. Using the same method, 30 patients were randomly selected for repeat measurements by 1 reviewer following a washout period. Ten additional patients with preoperative MRI and MRA of the same hip were identified to compare measurements between modalities using paired samples t test. Results: ICCs for measurements on MRIs and MRAs using these proposed measurements to compare inter-rater reliability were 0.981 and 0.985. ICCs calculated using measurements by a single reviewer following a washout period for intrarater reliability were 0.998 and 0.991. When comparing MRI and MRA measurements in the same patient, t test for all pooled measurements found no difference between modality (P = .283), and breakdown of measurements by quadrant found no difference in measurements (P > .05), with the exception of the inferior aspect of the capsule on coronal sequences (P = .023). Conclusions: In patients with FAIS, both MRI and MRA have excellent reliability for quantifying hip capsular thickness. A difference in capsular thickness was found only when comparing MRI and MRA on inferior coronal aspects of the hip capsule, indicating interchangeability of these imaging modalities when measuring the clinically important aspects of the hip capsule. Level of Evidence: Level IV, diagnostic case series.

Acetabular Labral Reconstruction: Review of Techniques and Outcomes.

PURPOSE OF REVIEW: To analyze advances in labral reconstruction, and to discuss the literature relating to efficacy, outcomes, and technical considerations of labral reconstruction. RECENT FINDINGS: The available evidence suggests that labral reconstruction is a safe and effective procedure that can improve pain and function in patients with severe and/or complex labral tears. The superiority of labral reconstruction over labral repair is uncertain, and it remains unclear what graft type and technique should be used in labral reconstructions. Labral reconstruction assists in restoring the function of the labrum of the hip. It consistently restores stability of the hip joint and demonstrates good clinical outcomes at follow-up. The optimal graft type, technique, and extent are still debated, and more research is needed. Ultimately, despite this uncertainty, labral reconstruction is proving to be a valuable tool for hip preservation specialists.