Changes in Muscle Volume and Composition After Treatment of Hip Dysplasia with Periacetabular Osteotomy.

Background: Periacetabular osteotomy (PAO) is a common treatment for pre-arthritic hip dysplasia in young adults. The purpose of this study was to better understand changes in muscle volume and composition after PAO visualized using magnetic resonance imaging (MRI). Methods: A prospectively collected series of individuals that underwent PAO for hip dysplasia were reviewed to identify subjects with pre- and postoperative MRI. In our practice, MRI was obtained preoperatively and greater than 6 months after PAO for persistent hip pain. MRI sequences were selected to optimize visualization of the muscle volume, fatty infiltration, and hip joint cartilage. MRI images were selected at predetermined bony landmarks and analyzed using 3D Slicer (©2021, www.slicer.org) software to measure muscle diameter and calculate muscle cross-sectional area (CSA) in 17 individual muscles surrounding the hip. Muscle atrophy was graded using the Goutallier classification for fatty infiltration and acetabular cartilage condition was graded using the Outerbridge classification. We compared pre- and postoperative muscle area and composition as well as cartilage for each case. Results: A series of six female patients met our inclusion criteria. Mean age was 26 years at time of surgery. All cases had MRI sequences adequate for muscle volume measurements. Fatty infiltration and cartilage changes were recorded in four subjects with appropriate MRI sequences. Separating muscle groups, external rotators underwent the largest volume increase. Hip flexors demonstrated mild volume decrease. CSA change among external rotators averaged +12%, hip flexors -9.3%, and hip abductors -9.2% after PAO. All muscles had either the same or increased fatty infiltration after surgery, with gluteus medius and iliacus undergoing the most average increase. Similarly, cartilage condition worsened by a small margin in this series. Conclusion: Our results provide preliminary indication that PAO may have noticeable effects on muscle characteristics and cartilage in the early postoperative period. This was a limited case series of subjects with adequate pre- and post-operative MRI imaging.Level of Evidence: IV.

Utilization of Physical Therapy Prior to Consultation for Hip Preservation Surgery.

Background: Comprehensive conservative care prior to arthroscopic hip surgery is recommended, but not all patients pursue a course of physical therapy (PT) prior to consulting a hip surgeon. The purpose of this study is to investigate the incidence and type of PT administered to patients with hip pain prior to consulting a hip surgeon. Methods: We conducted a single-center, questionnaire-driven study at a young adult hip preservation clinic that exclusively treats patients with hip pain. Thirty (88%) of thirty-four consecutive new patients answered the 15-item questionnaire. The questionnaire was designed to inquire about the reason for the visit, type of formal PT received (hip strengthening, leg strengthening etc.), and additional treatments received prior to the visit (electric stimulation, narcotics etc.). Descriptive statistics were utilized to quantify the reason for visit, PT prior to the visit, and type of exercises performed during physical therapy. Results: Overall, 21 (70%) patients received physical therapy prior to consulting with a hip surgeon. Of those who received PT, 91% (n=19) did hip strengthening exercises, 76% (n=16) did focused hip stretching exercises, 62% (n=13) did leg strengthening exercises, 57% (n=12) did joint mobilization exercises, and 52% (n=11) did focused core strengthening exercises. Only 48% (n=10) reported improvement in symptoms with PT. Of those who received additional treatments, 77% (n=20) took anti-inflammatory medications regularly, 50% (n=13) underwent electric stimulation, 31% (n=8) had chiropractic manipulation, 19% (n=5) underwent soft tissue mobilization, 15% (n=4) received steroid injections, and 12% (n=3) were prescribed narcotics for hip pain. Conclusion: The present study offers insight into the incidence and type of formal PT patients with hip pain receive before consulting a hip surgeon. Treatment methods during PT visits are variable, which makes determining outcomes of conservative care difficult to assess in this population.Level of Evidence: IV.

Physical Performance Tests Correlate With Patient-reported Outcomes After Periacetabular Osteotomy: A Prospective Study.

INTRODUCTION: Individuals with hip dysplasia report significant functional disability that improves with periacetabular osteotomy (PAO). Four physical performance measures (PPMs) have been recently validated for use with nonarthritic hip conditions; however, their ability to detect functional improvement and correlate with improvements in popular hip-specific patient-reported outcome (PRO) instruments after PAO is unknown. The purpose of this study was to evaluate the responsiveness of four PPMs up to 1 year after PAO, compare PPMs with established PRO measures at these time points, and report the acceptability and utility of PPMs for assessing outcomes after PAO. METHODS: Twenty-two participants aged 15 to 39 years completed the timed stair ascent (TSA), sit-to-stand five times (STS5), self-selected walking speed, four-square-step test, and seven hip-specific PRO measures before surgery and at approximately 6 months and 1 year after PAO. They completed questions regarding acceptability and utility of both types of testing. Wilcoxon rank sum test and unpaired Student t-tests were used to assess differences between time points; Spearman correlation and generalized linear modeling were used to determine the relationship between PPMs and PRO measures. RESULTS: Six months after PAO, participants showed significant improvements on all seven PRO instruments (P < 0.001) and on the STS5 (P = 0.01). At one year, these improvements were maintained and TSA also improved (P = 0.03). Improvement in other PPMs did not reach significance (P = 0.07 and 0.08). The STS5 test demonstrated moderate to strong correlation (|r| = 0.43 to 0.76, P < 0.05) with all PRO measures, and the TSA test demonstrated moderate to strong correlation with almost all measures (|r| = 0.43 to 0.58, P < 0.05). Correlations strengthened on subanalysis of participants with unilateral disease (n = 11) (|r| = 0.56 to 0.94, P < 0.05). All participants (100%) found PPM testing acceptable despite disability; 25% preferred PPMs to PRO measures, whereas 75% of participants found them equal in usefulness. DISCUSSION: The STS5 and TSA tests demonstrated moderate to very strong correlation with PRO measures at six and 12 months after PAO for dysplasia. These tests could be used as a functional outcome to supplement PRO instruments after PAO.