Microinstability of the Hip and the Splits Radiograph

Primary Total Hip Arthroplasty Outcomes for Labral Tears are Comparable to Advanced Osteoarthritis

BACKGROUND

There is a paucity of evidence on outcomes following total hip arthroplasty (THA) in patients who have symptomatic degenerative labral tears and mild to moderate osteoarthritis (OA). The purpose of this study was to determine if outcomes of primary THA in the setting of painful, symptomatic labral tear and mild to moderate arthritic changes were comparable to outcomes of primary THA performed for severe arthritic changes. Primary outcomes were patient-reported outcome (PRO) scores. Secondary outcomes included length of stay and perioperative complications.

METHODS

This was a retrospective investigation of all THAs between January 2018 and July 2022. There were 111 patients who had THA due to failure of nonoperative treatment of a degenerative labral tear without advanced arthritic changes (mild to moderate OA cohort, Kellgren-Lawrence Grades 1 to 3). These patients were matched to 111 patients who underwent THA for advanced OA (AOA cohort, Kellgren-Lawrence Grade 4). PROs included the Western Ontario McMaster Universities Arthritis Index (WOMAC). The average age for the labral tear cohort was 59 years, with 50.6% women, compared to 70 years (P < 0.001), and 49.4% women (P = 0.93) in the AOA cohort.

RESULTS

There were no differences in preoperative PROs, complications, or length of stay between groups. When looking at postoperative PROs between cohorts, the labral tear cohort had less improvement in WOMAC-Stiffness (24.3 versus 34.0, P = 0.005) and WOMAC-Functional limitation (26.3 versus 36.0, P = 0.005) at 12 months and greater improvement in WOMAC-Pain at 12 months (38.3 versus 34.7, P = 0.04). The Short Form 12-Physical function scores were significantly higher among the labral tear cohort compared to the AOA cohort at 12 months (48.5 versus 47.8, P < 0.001). The Short Form 12-Mental scores were significantly higher in the AOA cohort compared to the labral tear cohort at 3 months (47.1 versus 47.4, P = 0.02) and 12 months (46.7 versus 47.6, P < 0.001). In the multivariate analysis, the change in WOMAC-Pain at 12 months was significantly better for labral tear patients (odds ratio 7.5, P = 0.008, confidence interval 6.85 to 8.14).

CONCLUSIONS

Our study showed that patients who have symptomatic degenerative labral tears with mild to moderate arthritic changes have comparable outcomes to patients who have AOA following primary THA. Given suboptimal outcomes with hip arthroscopy for labral tear in the setting of early arthritis, primary THA can be a reasonable treatment modality for patients failing nonoperative treatments.

Excessive Femoral Anteversion Leading to Symptomatic Posterior Femoroacetabular Impingement, Cam Deformity of the Posterior Femoral Head-Neck Junction, and Anterior Hip Instability in a Dancer: A Case Report

CASE

An adolescent female dancer with excessive femoral anteversion presented with posterior and anterior hip pain aggravated by poses that required extension and external rotation. Imaging revealed an atypical cam deformity of the posterior head-neck junction. During surgery, the posterior head-neck junction was observed to impinge on the posterior acetabulum with anterior subluxation of the hip. After a derotational femoral osteotomy, the patient experienced resolution of her symptoms.

CONCLUSION

Excessive femoral anteversion can lead to reactive cam deformity, posterior intra-articular impingement, and anterior hip instability in patients who require repetitive hip extension and external rotation, such as ballet dancers.

Can Hip Passive Range of Motion Predict Hip Microinstability? A Comparative Study

Background

Hip microinstability is an increasingly recognized cause of pain and disability in young adults. It is unknown whether differences in passive hip range of motion (ROM) exist between patients with versus without hip microinstability.

Hypothesis

Underlying ligamentous and capsular laxity will result in differences in clinically detectable passive ROM between patients with femoroacetabular impingement (FAI), patients with microinstability, and asymptomatic controls.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

A retrospective review of all patients undergoing hip arthroscopy between 2012 and 2018 was conducted. Patients with a diagnosis of isolated microinstability based on intraoperative findings were identified and classified as having isolated FAI, instability, or FAI + instability. Patients without a history of hip injury were included as controls. Range of motion was recorded in the supine position for flexion, internal rotation, and external rotation. Univariate and multivariate analysis was performed on each measurement in isolation as well as combinations of motion to include total rotation arc, flexion + rotation arc, and flexion + 2× rotation arc Models were then created and tested to predict instability status.

Results

In total, 263 hips were included: 69 with isolated instability, 50 with FAI, 50 with FAI + instability, and 94 control hips. A higher proportion of patients in the instability and FAI + instability groups were female compared with the FAI and control groups (P < .001). On univariate analysis, differences were found in all groups in all planes of motion (P < .001). Multivariable analysis demonstrated differences in all groups in flexion and flexion + rotation arc. In symptomatic patients, the best performing predictive model for hip microinstability was flexion + rotation arc ≥200° (Akaike information criterion, 132.3; P < .001) with a sensitivity of 68.9%, specificity of 80.0%, positive predictive value of 89.1%, and negative predictive value of 51.9%.

Conclusion

Patients with hip microinstability had significantly greater ROM than symptomatic and asymptomatic cohorts without hip microinstability. Symptomatic patients with hip flexion + rotation arc ≥200° were highly likely to have positive intraoperative findings for hip microinstability, whereas instability status was difficult to predict in patients with a flexion + rotation arc of <200°.

Diagnosing Hip Microinstability: an international consensus study using the Delphi methodology

PURPOSE

Hip microinstability is a relatively new diagnosis which is increasingly being discussed in the literature and yet there are no clear guidelines for making a diagnosis. Microinstability has generally been defined as persistent excessive hip motion that has become symptomatic especially with pain. This aim of this Delphi study was to seek expert opinion to formulate a diagnostic criteria for hip microinstability.

METHODS

A Delphi methodology was used for this consensus study. A literature search was conducted on PubMed up to March 2019 using the keywords ((hip) and (microinstability)) to identify relevant articles on this topic. All relevant criteria used for diagnosing hip microinstability were collated to create a questionnaire and further criterion suggested by the experts were included as well. Four rounds of questionnaires were delivered via an online survey platform. Between each round the authors acted as administrating intermediaries, providing the experts with a summary of results and synthesising the next questionnaire. The expert panel was comprised of 27 members: 24 (89%) orthopaedic surgeons and 3 (11%) physiotherapists from around the world.

RESULTS

Expert panel participation in rounds 1-4 was: 27 (100%), 20 (74%), 21 (78%) and 26 (96%) respectively. A literature review by the authors identified 32 diagnostic criteria to populate the first questionnaire. Experts suggested amending three criteria and creating five new criteria. The panel converged on ranking 3 (8%) of criteria as "Not important", 20 (54%) as "Minor Factors" and 14 (38%) as "Major Factors". No criteria was ranked as "Essential". Criteria were subcategorised into patient history, examination and imaging. Experts voted for a minimum requirement of four criteria in each subcategory, including at least six "Major factors". The final diagnostic tool was approved by 20 (77%) of the final round panel.

CONCLUSION

This study describes the first known expert consensus on diagnosing hip microinstability. The relative complexity of the final diagnostic tool is illustrative of the difficulty clinicians' face when making this diagnosis.

LEVEL OF EVIDENCE

V.

Editorial Commentary: Axial Stress Examination Under Anesthesia Provides a Highly Reliable Test for Measurement of Hip Distraction

Symptomatic hip microinstability is now recognized as one of the most common surgical indications for revision hip arthroscopy. Hip microinstability can be difficult to diagnose, particularly because of the multifactorial etiology and limited physical examination maneuvers that provide objective testing of gross hip stability. One measure of hip stability is axial stability evaluated under traction intraoperatively. Recent research has suggested that average axial stability of the hip is decreased after primary hip arthroscopy-although not in all cases. Recognizing that there are many additional factors that may contribute to hip microinstability, as well as the fact that axial stability is only one assessment of overall stability of the hip, is important in the evaluation of microinstability in the setting of prior hip arthroscopy.

Correlates of Manual Therapy and Acupuncture Use Among Rural Patients Seeking Conventional Pain Management: A Cross-sectional Study

OBJECTIVE

In this cross-sectional study, we examined correlates of manual therapy (spinal manipulation, massage therapy) and/or acupuncture use in a population engaging in conventional pain care in West Virginia.

METHODS

Participants were patients (aged 18+ years) from 4 Appalachian pain and rheumatology clinics. Of those eligible (N = 343), 88% completed an anonymous survey including questions regarding health history, pain distress (Short Form Global Pain Scale), prescription medications, and current use of complementary health approaches for pain management. We used age-adjusted logistic regression to assess the relation of sociodemographic, lifestyle, and health-related factors to use of manual therapies and/or acupuncture for pain (complete-case N = 253).

RESULTS

The majority of participants were white (92%), female (56%), and middle aged (mean age, 54.8 ± 13.4 years). Nearly all reported current chronic pain (94%), and 56% reported ≥5 comorbidities (mean, 5.6 ± 3.1). Manual therapy and/or acupuncture was used by 26% of participants for pain management (n = 66). Current or prior opioid use was reported by 37% of those using manual therapies. Manual therapy and/or acupuncture use was significantly elevated in those using other complementary health approaches (adjusted odds ratio, 3.0; 95% confidence interval, 1.5-5.8). Overall Short Form Global Pain Scale scores were not significantly associated with use of manual therapies and/or acupuncture after adjustment (adjusted odds ratio per 1-point increase, 1.01; 95% confidence interval, 1.00-1.03).

CONCLUSION

We found no evidence for an association of pain-related distress and use of manual therapies and/or acupuncture, but identified a strong association with use of dietary supplements and mind-body therapies. Larger studies are needed to further examine these connections in the context of clinical outcomes and cost-effectiveness in rural adults given their high pain burden and unique challenges in access to care.

Hypermobile Disorders and Their Effects on the Hip Joint

Hypermobility, or joint hyperlaxity, can result from inherited connective tissue disorders or from micro- or macrotrauma to a joint. The supraphysiologic motion of the hip joint results in capsuloligamentous damage, and these patients have a propensity to develop femoroacetabular impingement syndrome (FAIS) and labral injury. In this review, the recent literature evaluating the definitions, history, incidence, genetics, and histology of hypermobile disorders is investigated. We then review the clinical evaluation, natural history, and resulting instability for patients presenting with a hypermobile hip. Lastly, treatment options and outcomes will be highlighted.

Hip Instability in the Athlete: Anatomy, Etiology, and Management

In this review, the recent literature evaluating the anatomic considerations, etiology, and management options for athletes with hip instability are investigated. Studies on the osseous, chondrolabral capsuloligamentous, and dynamic muscular contributions to hip stability are highlighted. Microinstability, iatrogenic instability, and femoroacetabular impingement-induced instability are discussed with a focus on demographic and outcomes research in athletes. Surgical techniques including both open and arthroscopic approaches are additionally evaluated.

Cam Osteochondroplasty for Femoroacetabular Impingement Increases Microinstability in Deep Flexion: A Cadaveric Study

PURPOSE

The purpose of this in vitro cadaveric study was to examine the contributions of each surgical stage during cam femoroacetabular impingement (FAI) surgery (i.e., intact-cam hip, T-capsulotomy, cam resection, and capsular repair) toward hip range of motion, translation, and microinstability.

METHODS

Twelve cadaveric cam hips were denuded to the capsule and mounted onto a robotic tester. The hips were positioned in several flexion positions-full extension, neutral (0°), 30° of flexion, and 90° of flexion-and performed internal-external rotations to 5 Nm of torque in each position. The hips underwent a series of surgical stages (T-capsulotomy, cam resection, and capsular repair) and were retested after each stage. Changes in range of motion, translation, and microinstability (overall translation normalized by femoral head radius) were measured after each stage.

RESULTS

Regarding range of motion, cam resection increased internal rotation at 90° of flexion (change in internal rotation = +6°, P = .001) but did not affect external rotation. Capsular repair restrained external rotation compared with the cam resection stage (change in external rotation = -8° to -4°, P ≤ .04). In terms of translation, the hip translated after cam resection at 90° of flexion in the medial-lateral plane (change in translation = +1.9 mm, P = .04) relative to the intact and capsulotomy stages. Regarding microinstability, capsulotomy increased microinstability in 30° of flexion (change in microinstability [Δ_M] = +0.05, P = .003), but microinstability did not further increase after cam resection. At 90° of flexion, microinstability did not increase after capsulotomy (Δ_M = +0.03, P = .2) but substantially increased after cam resection (Δ_M = +0.08, P = .03), accounting for a 31% change with respect to the intact stage.

CONCLUSIONS

Cam resection increased microinstability by 31% during deep hip flexion relative to the intact hip. This finding suggests that iatrogenic microinstability may be due to separation of the labral seal and resected contour of the femoral head.

CLINICAL RELEVANCE

Our in vitro study showed that, at time zero and prior to postoperative recovery, excessive motion after cam resection could disrupt the labral seal. Complete cam resection should be performed cautiously to avoid disruption of the labral seal and postoperative microinstability.

Microinstability of the hip: a systematic review of the imaging findings

OBJECTIVES

To undertake a systematic review of the morphologic features associated with hip microinstability and determine whether there are suggestive or diagnostic imaging findings.

METHODS

Four electronic databases were searched up to September 2019 to identify original research reporting morphologic features in individuals with either a clinical diagnosis of hip microinstability (instability without overt subluxation/dislocation) or those with symptomatic laxity demonstrated on imaging (increased femoral head translation/distraction or capsular volume). Studies focussing on individuals with pre-existing hip conditions (including definite dysplasia (lateral centre edge angle < 20°), significant trauma, previous dislocation or surgery were excluded. Methodological quality was assessed by the Quality Assessment of Diagnostic Accuracy Studies 2 tool.

RESULTS

Twenty-two studies met inclusion criteria (clinical diagnosis of microinstability n = 15 and demonstration of laxity n = 7). Imaging information gathered from the studies includes radiographs (n = 14), MRI (n = 6), MR arthrography (n = 4), CT (n = 1) and intraoperative examination. Most studies exhibited design features associated with an overall high or unclear risk of bias. Some dysplastic features are associated with microinstability or laxity reference measures; however, microinstability is frequently diagnosed in those with a lateral centre edge angle > 25°. Other associated imaging findings reported include impingement morphology, anterior labral tearing, femoral head chondral injury, ligamentum teres tears and capsular attenuation.

CONCLUSIONS

The current literature does not provide strong evidence for imaging features diagnostic of microinstability. In the appropriate clinical context, dysplastic morphology, anterior labral tears and ligamentum teres tears may be suggestive of this condition although further research is needed to confirm this.

PROSPERO REGISTRATION

CRD42019122406.

Is the Iliopsoas a Femoral Head Stabilizer? A Systematic Review

PURPOSE

To perform a systematic review of biomechanical and clinical studies to determine whether the iliopsoas is a femoral head stabilizer.

METHODS

A systematic review was conducted using Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Inclusion criteria were any human clinical (Levels I-IV evidence) or laboratory studies that investigated the role of the iliopsoas as a stabilizer of the hip. Exclusion criteria included studies that investigated patients undergoing spine surgery or those with a total hip arthroplasty or hip hemiarthroplasty. Study methodologic quality for clinical-outcomes studies were analyzed using the Modified Coleman Methodology Score. Because of the heterogeneity in the participants and interventions, no quantitative assimilative meta-analysis was performed.

RESULTS

Eight articles were analyzed (3 biomechanical [35 cadavers and 18 healthy subjects]; 5 clinical outcomes studies [537 subjects, 207 arthroscopic iliopsoas tenotomies]). Two in vivo biomechanical studies identified the iliopsoas as an anterior hip stabilizer. One cadaveric study identified the iliopsoas as a femoral head stabilizer at 0o-15o of hip flexion. Two clinical studies demonstrated the role of the iliopsoas as a dynamic hip stabilizer, particularly in patients with increased femoral version (greater than 15˚-25˚). Two studies reported cases of atraumatic anterior hip dislocations after arthroscopic iliopsoas tenotomies.

CONCLUSIONS

Evidence from biomechanical and clinical studies may suggest that the iliopsoas is a dynamic anterior femoral head stabilizer.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III and IV plus biomechanical studies.

An Injury Prevention Program for Professional Ballet: A Randomized Controlled Investigation

BACKGROUND

Few investigations have examined dance-specific injury prevention programs (IPPs), and no published randomized controlled trials are available that evaluate IPPs for dance.

HYPOTHESIS

The implementation of an IPP will significantly reduce the risk of injury in professional ballet dancers.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

A randomized controlled trial was designed that entailed a superiority model for the intervention group. All professional dancers from a single ballet company were eligible to participate. Randomization and allocation were performed before the start of the season. The control group practiced and performed without change to preexisting standard operating practice. The IPP group was instructed to perform a 30-minute exercise program 3 times per week over the 52-week study period. Injuries were recorded. Standard continuous and categorical data comparisons and correlations were used. Cox proportional hazards regression models for recurrent failures were used wherein the hazard ratio indicates the relative likelihood of injury in the control versus intervention groups.

RESULTS

Of the 52 eligible dancers, 75% (n = 39) participated. Of these 39 dancers, 19 (9 males, 10 females; mean age, 26.6 ± 4.0 years) were randomized to the control group and 20 (11 males, 9 females; mean age, 25.1 ± 5.1 years) to the IPP group. No significant (P > .05) difference was found in baseline demographics between groups. A total of 116 injuries were recorded for the entire study population (49 IPP; 67 control). Traumatic and chronic injuries accounted for 54% and 46% of injuries, respectively. The injury rate was 82% less (IPP hazard ratio, 0.18; z = -2.29; P = .022) in the IPP group after adjustment for confounding variables, and time between injuries was 45% longer (IPP hazard ratio, 0.55; z = -2.20; P = .028) than for controls.

CONCLUSION

The present study is the first prospective randomized controlled investigation of an IPP for professional ballet. The results showed an 82% decrease in injury rate for the intervention group and an extended period from previous injury to subsequent injury.

REGISTRATION

NCT04110002 (ClinicalTrials.gov identifier).

Gender-Specific Sexual Activity After Hip Arthroscopy for Femoroacetabular Impingement Syndrome: Position Matters

BACKGROUND

There is limited evidence on the safety of return to sexual activity after hip arthroscopy.

AIM

To determine the positional safety of sexual activity after hip arthroscopy relative to hip instability and/or impingement risk.

STUDY DESIGN

This study is an observational study.

METHODS

12 common sexual positions were identified based on previous research. Gender-specific hip motion was then assessed for the possibility of postarthroscopic hip instability (due to disruption of iliofemoral ligament [interportal capsulotomy] repair) and/or impingement (labral or capsular compressive stress with disrupted repair) for all 12 positions (both right and left hips; 15 unique male and 14 unique female positions). Instability risk was defined as greater than 0° hip extension, greater than 30° external rotation (ER), or greater than 30° abduction. Impingement risk was defined as greater than 90° hip flexion, greater than 10° internal rotation, and greater than 10° adduction.

OUTCOMES

A majority of both male and female sexual positions caused either instability or impingement, with only 4 positions in women and 4 positions in men deemed "safe" by avoiding excessive hip motion.

RESULTS

Return to sexual activity after hip arthroscopy may cause instability in 10/15 of male positions and 5/14 female positions. Most male positions (6/10) were at risk for instability because of excessive ER. 2 positions were unstable because of a combination of ER and extension, one was due to extension, and one abduction. In female instability positions, all 5 were unstable because of excessive abduction. Impingement may be observed in 5 of 15 male positions and 6 of 14 female positions. In male impingement positions, all were due to excessive adduction. 4 female positions risked impingement due to excessive flexion and 2 positions due to internal rotation.

CLINICAL IMPLICATIONS

This study demonstrates risks that should be considered when counseling patients preoperatively and postoperatively regarding sexual activity.

STRENGTHS & LIMITATIONS

This study closely models a hip preservation patient population by using 2 young and otherwise healthy individuals. The most significant limitation of this investigation was its basis with only 2 young healthy volunteers (one male, one female) in a single motion capture session using surface-based spherical retroreflective markers from a previous investigation.

CONCLUSION

After hip arthroscopy, patients need to be made aware of the possibility of hip instability (10 of 15 men; 5 of 14 women) and impingement (5 of 15 men; 6 of 14 women) due to excessive hip motion that may compromise their outcome. Morehouse H, Sochacki KR, Nho SJ, et al. Gender-Specific Sexual Activity After Hip Arthroscopy for Femoroacetabular Impingement Syndrome: Position Matters. J Sex Med 2020;17:658-664.

Radiographic analysis of subclinical appearances of the hip joint among patients with labral tears

Objective

Labral tears can be complicated by hip diseases, including osteoarthritis or femoral acetabular impingement. To accurately plan hip arthroscopy or subsequent conversion to total hip arthroplasty, the presence of bony abnormalities in the hip joint must be evaluated. This study aimed to elucidate the utility of multiplanar reconstruction computed tomography (mCT) for the detection of subclinical coincidence of osteoarthritis or femoral acetabular impingement with a labrum tear.

Materials and methods

We retrospectively analysed 34 patients (36 hips) with labrum tears without apparent osteoarthritis or hip dysplasia from 2012 to 2015. The joint spaces were calculated using radiographs or mCT, and the detection rates of degenerative cyst and herniation pit were compared.

Results

Narrow joint spaces (< 2 mm) were more clearly detected in mCT (p < 0.05, chi-square analysis) than in radiographs. The detection rate of cysts in the acetabulum was 8.3% using radiographs and 36.1% using mCT (p < 0.001, chi-square analysis). Additionally, the detection of herniation pit was 8.3% and 25.0% using radiographs and mCT, respectively (p = 0.053, chi-square analysis).

Conclusion

We performed the radiographic analysis of patients with labral tears using radiographs and mCT. The mCT allowed for fine detection of narrow joint spaces and subtle subclinical appearances. The results of this study may provide surgeons with more appropriate strategies for the treatment of labral tears.

Return to Dance and Predictors of Outcome After Hip Arthroscopy for Femoroacetabular Impingement Syndrome

PURPOSE

To investigate the rate of return to dance and factors influencing this primary outcome after hip arthroscopy for the treatment of femoroacetabular impingement syndrome.

METHODS

A consecutive series of self-identified dancers with femoroacetabular impingement syndrome was included. To assess for the impact of hypermobility on outcomes, patients were classified as having either generalized joint laxity (GJL) or no GJL based on the Beighton-Horan Joint Mobility Index. A return-to-dance survey, the modified Harris Hip Score, and the Hip Outcome Score (HOS)-Activities of Daily Living and HOS-Sports-Specific subscales were collected preoperatively and postoperatively at 6, 12, 24, and 36 months. The preoperative-to-postoperative outcome score change was compared using the minimal clinically important difference and patient acceptable symptomatic state. Return to dance was evaluated regarding (1) return to any dance activity, (2) return to prior level of dance, and (3) number of hours of dance participation after surgery. Clinical and demographic predictors and return to dance were analyzed using univariate or bivariate analysis where appropriate.

RESULTS

The study included 64 consecutive dancers (62 female and 2 male patients) (mean age, 22.3 ± 9.4 years; body mass index, 22.8 ± 4.1) with a mean follow-up period of 23.0 months. Postoperatively, 62 patients (97%) returned to dance at an average of 6.9 ± 2.9 months; 40 patients (62.5%) reported that they returned to a better level of participation, whereas 20 dancers (31%) returned to the same level of participation. Statistically significant increases were observed for the HOS-Activities of Daily Living subscale (60.5 ± 19.5 vs 92.4 ± 11.8, P < .001), HOS-Sports-Specific subscale (40.3 ± 20.3 vs 83.5 ± 19.4, P < .001), and modified Harris Hip Score (57.0 ± 13.6 vs 86.6 ± 13.9, P < .001). There was, however, a significant decrease in the number of hours of dance postoperatively: 11.5 ± 8.2 h/wk preoperatively versus 9.0 ± 7.3 h/wk postoperatively (P = .041). All postoperative hip outcome measures showed statistically significant (P < .001) and clinically relevant improvements. Patient-reported outcomes and return time showed no significant differences between the patient groups with GJL and without GJL (P = .1 and P = .489, respectively). For competitive dancers, a correlation was shown with a shorter time to return to dance (r² = 0.45, P = .001), but there were no significant differences by skill level in patient-reported outcomes or dance hours.

CONCLUSIONS

After hip arthroscopy, 97% of dancers returned to dance at an average of 6.9 months, with most dancers dancing at a level higher than their preoperative status. Dance experience level was the only significant factor influencing return-to-dance outcomes, with competitive dancers showing a faster return to dancing.conclusion LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Arthroscopic capsular repair using proximal advancement for instability following hip arthroscopic surgery: a case report

Arthroscopic capsular reconstruction has been reported for joint capsule tear and joint instability after hip arthroscopic surgery. However, the procedure is complicated and requires proficiency. Herein, we present a case of mild dysplasia and instability following arthroscopic surgery performed against pain due to synovitis and labral injury. The patient refused osteotomy of the hip joint, so we performed hip arthroscopic surgery using a new method of arthroscopic capsular repair using proximal advancement. A 37-year-old woman underwent hip arthroscopic surgery two times at the right side and periacetabular osteotomy at the left side. She noticed instability of the right hip joint after the second hip arthroscopic surgery. For the joint capsular management at the second surgery, which was not suitable for capsular plication, arthroscopic capsular repair using proximal advancement was performed by lifting the distal capsule to the acetabular margin. This method is less technically demanding compared with capsular reconstruction, and it can securely achieve joint stability by retensioning the joint capsule and iliofemoral ligament. Patient-reported outcomes were assessed by modified Harris hip score (mHHS), non-arthritic hip score (NAHS) and visual analog scale (VAS). The patient reported an increase in the mHHS from 35.2 pre-operatively to 90.1, the NAHS increased from 50 pre-operatively to 88.7, and the VAS score improved from 9 points pre-operatively to 1 point at 2 years post-operatively. To our knowledge, this is the first report on arthroscopic capsular repair using proximal advancement in a patient with hip instability following hip arthroscopic surgery.

There Is a Significant Discrepancy Between "Big Data" Database and Original Research Publications on Hip Arthroscopy Outcomes: A Systematic Review

PURPOSE

The purpose of this study was to compare (1) major complication, (2) revision, and (3) conversion to arthroplasty rates following hip arthroscopy between database studies and original research peer-reviewed publications.

METHODS

A systematic review was performed using PRISMA guidelines. PubMed, SCOPUS, SportDiscus, and Cochrane Central Register of Controlled Trials were searched for studies that investigated major complication (dislocation, femoral neck fracture, avascular necrosis, fluid extravasation, septic arthritis, death), revision, and hip arthroplasty conversion rates following hip arthroscopy. Major complication, revision, and conversion to hip arthroplasty rates were compared between original research (single- or multicenter therapeutic studies) and database (insurance database using ICD-9/10 and/or current procedural terminology coding terminology) publishing studies.

RESULTS

Two hundred seven studies (201 original research publications [15,780 subjects; 54% female] and 6 database studies [20,825 subjects; 60% female]) were analyzed (mean age, 38.2 ± 11.6 years old; mean follow-up, 2.7 ± 2.9 years). The database studies had a significantly higher age (40.6 + 2.8 vs 35.4 ± 11.6), body mass index (27.4 ± 5.6 vs 24.9 ± 3.1), percentage of females (60.1% vs 53.8%), and longer follow-up (3.1 ± 1.6 vs 2.7 ± 3.0) compared with original research (P < .0001 for all). Ninety-seven (0.6%) major complications occurred in the individual studies, and 95 (0.8%) major complications occurred in the database studies (P = .029; relative risk [RR], 1.3). There was a significantly higher rate of femoral neck fracture (0.24% vs 0.03%; P < .0001; RR, 8.0), and hip dislocation (0.17% vs 0.06%; P = .023; RR, 2.2) in the database studies. Reoperations occurred at a significantly higher rate in the database studies (11.1% vs 7.3%; P < .001; RR, 1.5). There was a significantly higher rate of conversion to arthroplasty in the database studies (8.0% vs 3.7%; P < .001; RR, 2.2).

CONCLUSIONS

Database studies report significantly increased major complication, revision, and conversion to hip arthroplasty rates compared with original research investigations of hip arthroscopy outcomes.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies.

Editorial Commentary: Caveat Flexor-To Release or Not to Release the Iliopsoas, That Is the Question

In nonarthritic patients with femoroacetabular impingement syndrome, borderline dysplasia, and symptomatic iliopsoas snapping, arthroscopic iliopsoas fractional lengthening carries a significant risk of postarthroscopic instability. The iliopsoas is a dynamic stabilizer of the anterior hip. Thus, although statistically significant and clinically important improvements in hip function have the potential to be achieved with iliopsoas fractional lengthening, surgeons must be supremely confident in their ability to perform a secure capsular plication, labral preservation (not debridement), comprehensive cam correction, avoidance of intra-abdominal fluid extravasation, release of all iliopsoas tendon bands (if bifid or trifid), and ensure that femoral version is normal or low, neck-shaft angle is not excessively valgus, the dysplasia magnitude is no more than mild, and that there is no excessive soft tissue hypermobility. If these goals can be met, then excellent outcomes can be achieved. If not, then an iliopsoas fractional lengthening should not be performed.

Does Capsular Laxity Lead to Microinstability of the Native Hip?

BACKGROUND

Hip "microinstability" is commonly cited as the cause of symptoms that occur in the presence of translation of the femoral head away from conformity with the acetabular fossa. However, there is still no consistent objective criteria defining its presence and biomechanical basis. One hypothesis is that abnormal motion of the articular surfaces occurs because of capsular laxity, ultimately leading to clinical symptoms.

PURPOSE

To determine the relationship between capsular laxity and abnormal rotation and translation of the hip.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight cadaveric hips were dissected down to the capsule and mounted in a customized multiaxial hip activity simulator. Each specimen was loaded with 5 N·m of internal and external rotational torque in full extension and 0°, 30°, 60°, and 90° of flexion. During testing, the relative position and rotation of the femur and the pelvis were monitored in real time with a 6-camera motion analysis system. The testing was repeated after capsular laxity was generated by placing a regular array of incisions ("pie crusting") in the iliofemoral, pubofemoral, and ischiofemoral ligaments. Joint rotation and femoral head translation were calculated with specimen-specific models. A hip microinstability index was defined as the ratio between the length of the locus of the femoral head center and the radius of the femoral head during rotation from extension to 90° of flexion.

RESULTS

In intact hips, the components of femoral head translation were within 0.5 mm in positions close to neutral (<30° of flexion). Capsular modification led to significant increases in internal and external rotation ( P < .01) and in the translation of the femoral head center at different positions ( P < .05). Compared with intact hips, the femoral head was inferiorly displaced during external rotation and anteroinferiorly during internal rotation. The length of the locus of the femoral head center increased from 3.61 ± 1.30 mm to 5.35 ± 1.83 mm for external rotation ( P < .05) and from 6.24 ± 1.48 mm to 8.21 ± 1.42 mm for internal rotation ( P < .01). The correlations between rotational laxity and the total translation of the femoral head were not significant, with coefficients of 0.093 and 0.006 in external and internal rotation, respectively. In addition, the hip microinstability index increased from 0.40 ± 0.08 for intact hips to 0.55 ± 0.09 for modified hips ( P < .01).

CONCLUSION

The native hip approximates a concentric ball-and-socket joint within 30° of flexion; however, beyond 30° of flexion, the femoral head translation reached as high as 4 mm. Capsular laxity leads to microinstability of the hip, as indicated by significantly increased joint rotations and femoral head translations and an abnormal movement path of the femoral head center. However, there was no correlation between rotational laxity and the increase in femoral head translation.

CLINICAL RELEVANCE

Capsular laxity alters normal kinematics (joint rotation and femoral head translation) of the hip, potentially leading to abnormal femoral-acetabular contact and joint degeneration.

Extra-articular hip impingement: a review of the literature

Hip and groin pain is a common clinical problem. Multiple causes can generate hip or groin pain, often sharing clinical and demographic characteristics. Diagnostic imaging tests play an important role in the etiological diagnosis. New forms of extra-articular hip impingement have recently been recognized as a cause of hip pain and limited function especially in young active patients. These conditions include ischiofemoral impingement, anterior inferior iliac spine and subspine impingement, iliopsoas impingement and greater trochanteric-pelvic impingement. In general, they are caused by a mechanical conflict with an abnormal or excessive contact between the proximal femur and pelvis and/or soft tissue between them. In this manuscript we review the physiopathology, clinical presentation, the most common radiologic findings and treatment of these forms of extra-articular hip impingement.

Decreased Synovial Inflammation in Atraumatic Hip Microinstability Compared With Femoroacetabular Impingement

PURPOSE

To compare the inflammatory profile of hip synovial tissue in those with atraumatic microinstability to patients with femoroacetabular impingement (FAI).

METHODS

Patients with cam and mixed-type FAI (FAI group) and patients with hip instability underwent sampling of the anterolateral synovium. Demographic data, intraoperative measurements, and functional outcome scores (International Hip Outcomes Tool and Short Form-12) were recorded. Cryosections were stained and examined under light microscopy as well as confocal fluorescent microscopy for anti-CD45 (common leukocyte antigen), anti-CD31 (endothelial), and anti-CD68 (macrophage) cell surface markers. A grading system was used to quantify synovitis under light microscopy whereas digital image analysis was used to quantify immunofluorescence staining area. Comparison were made with Student t test, Mann-Whitney U, χ², and regression analysis.

RESULTS

There were 12 patients in the FAI group and 5 in the instability group. Mean age was not significantly different (P > .05), but there was a significantly greater proportion of females in the instability group versus the FAI group (P < .001). There was a significant correlation (r = 0.653; P = .005) between number of turns needed for 10 mm of distraction and increased synovitis. Synovitis scores also were increased significantly in patients with cam morphology and articular cartilage damage (P = .024) versus those without. Immunohistochemistry did not reveal differences (P > .082) between the instability and FAI groups, but CD68 staining was significantly greater in those with cam morphology and cartilage damage (P < .045). CD45+/CD68- cells were noted in the perivascular area while CD45+/CD68+ cells were noted within the synovial lining in both groups.

CONCLUSIONS

Increased synovial inflammation was associated with an increased number of turns to achieve joint distraction. Both instability and FAI groups demonstrated baseline levels of synovial inflammation. Synovitis scores also were increased in patients with cartilage damage.

CLINICAL RELEVANCE

An understanding of the molecular and cellular mechanisms behind both hip instability and FAI may lead to novel therapeutic anti-inflammatory therapy, which may serve as an adjunct to treatment of mechanical abnormalities in this conditions.

Microinstability of the hip: a previously unrecognized pathology

BACKGROUND

Hip microinstability is an established diagnosis; however, its occurrence is still debated by many physicians. Diagnosis of hip microinstability is often challenging, due to a lack of specific signs or symptoms, and patients may remain undiagnosed for long periods. This may lead to early manifestation of degenerative joint disease. Consequently, careful patient and family history must be obtained and diagnostic imaging should follow. After a thorough clinical evaluation of the patient with suspected hip microinstability, the physician should focus on how to improve symptoms and functionality in daily and sports activities.

PURPOSE

The purpose of this review article was to give a current update regarding this diagnosis and to provide a complete diagnostic approach in order to effectively treat hip microinstability.

METHODS

We reviewed the literature on the diagnosis, the non-operative and operative indications for the treatment of this complex and often misdiagnosed pathology.

CONCLUSION

Conservative treatment is considered the best initial approach, though, surgical intervention should be considered if symptoms persist or other hip pathology exists. Successful surgical intervention, such as hip arthroscopy, should focus on restoring the normal anatomy of the hip joint in order to regain its functionality. The role of the hip joint capsule has gained particular research interest during the last years, and its repair or reconstruction during hip arthroscopy is considered necessary in order to avoid iatrogenic hip microinstability. Various capsular closure/plication techniques have been developed towards this direction with encouraging results.

LEVEL OF EVIDENCE

V.

Microinstability of the hip: A review

With the development of conservative hip surgery techniques, new entities such as microinstability have been identified. Microinstability is a painful supra-physiological mobility of the hip. It results from the association of architectural and functional abnormalities impairing joint stability. These risk factors concern hip joint bone architecture or peri-articular soft tissues. Bone abnormalities are identified on hip assessment parameters. Soft tissues also play a key role in the static and dynamic stability of the hip: the joint capsule, labrum, ligamentum teres and adjacent myotendinous structures affect joint coaptation; any abnormality or iatrogenic lesion concerning these structures may constitute a risk factor for microinstability. Diagnosis is based on interview, clinical examination and imaging. Findings of labral lesions or femoro-acetabular impingement do not rule out microinstability; they may be associated. Treatment is based first on physiotherapy for muscle reinforcement to improve joint coaptation. In case of failure, arthroscopic surgery is indicated for femoro-acetabular impingement and capsular plicature which is being evaluated. Periacetabular osteotomy or shelf acetabuloplasty may be indicated, according to the severity of joint bone architecture abnormality. Microinstability is a multifactorial entity. Lesions induced by microinstability may in turn become risk factors for aggravation. Diagnosis and indications for surgery are thus difficult to establish. Only full clinical examination and exhaustive imaging assessment allow microinstability and associated lesions to be identified.

Hip labral repair: options and outcomes

The importance of the acetabular labrum has been increasingly recognized, playing a critical role in both normal anatomy and abnormal pathology of the hip joint. The labrum increases acetabular surface area and volume, providing a stable and durable articulation. The fibrocartilaginous composition affords a tissue capable of a lifetime of normal function in the absence of significant osseous pathology. In the setting of femoroacetabular impingement (FAI) or dysplasia, bony biomechanics may cause labral injury, which may translate to patient symptoms. Long-term consequences of labral tears may include joint degeneration. Labral preservation surgery emphasizes retention of the form and function of the labrum, prioritizing labral repair (in the presence of reparable tissue) and reconstruction (in the absence of reparable tissue) over debridement. Patient-reported outcomes have consistently demonstrated significantly better results following labral repair versus debridement. In conjunction with correction of osseous abnormalities, labral surgery can improve short-term outcomes and potentially reduce the risk of long-term osteoarthritis.

Hip instability: a review of hip dysplasia and other contributing factors

BACKGROUND

Hip instability has classically been associated with developmental dysplasia of the hip (DDH) in newborns and children. However, numerous factors may contribute to hip instability in children, adolescents, and adults.

PURPOSE

This review aims to concisely present the literature on hip instability in patients of all ages in order to guide health care professionals in the appropriate diagnosis and treatment of the various disorders which may contribute to an unstable hip.

METHODS

We reviewed the literature on the diagnosis and surgical management of hip dysplasia and other causes of hip instability.

CONCLUSIONS

Multiple intra- and extra-articular variables may contribute to hip instability, including acetabular bony coverage, femoral torsion, femoroacetabular impingement, and soft tissue laxity. Physical examination and advanced imaging studies are essential to accurately diagnose the pathology contributing to a patient's unstable hip. Conservative management, including activity modification and physical therapy, may be used as a first-line treatment in patients with intra-articular hip pathology. Patients who continue to experience symptoms of pain or instability should proceed with arthroscopic or open surgical treatment aimed at correcting the underlying pathology.

LEVEL OF EVIDENCE

V.

Hip Dislocation or Subluxation After Hip Arthroscopy: A Systematic Review

PURPOSE

To determine patient- and surgery-specific characteristics of patients sustaining postarthroscopic hip dislocation or subluxation.

METHODS

A systematic review of multiple medical databases was registered with PROSPERO and performed using Preferred Reporting Items for Systemic Reviews and Meta-Analysis guidelines. Level I to IV clinical outcome studies reporting the presence of hip dislocation or subluxation after hip arthroscopy were eligible. Length of follow-up was not an exclusion criterion. All patient- and surgery-specific variables were extracted from each, specifically evaluating osseous morphology and resection details; labral, iliopsoas, ligamentum teres, and capsular management; generalized ligamentous laxity; instability direction and mechanism; management; and outcome. Study authors were individually contacted to assess most recent outcome.

RESULTS

Ten articles with 11 patients were analyzed (mean patient age: 36.6 ± 12.3 years). There were 9 hip dislocations and 2 subluxations. Mean time between surgery and dislocation was 3.2 ± 4.0 months (range: recovery room to 14 months). Anterior was the most frequent dislocation direction (8 cases). Acetabular undercoverage (preoperative dysplasia or iatrogenic rim over-resection) was observed in 5 cases. Labral debridement was performed in 5 cases, iliopsoas tenotomy in 3 cases, and ligamentum teres debridement in 1 case. A "T" capsulotomy was created in 1 case (isolated interportal in other 10 cases). Capsular closure was performed in 2 cases (both interportal). Generalized ligamentous laxity was diagnosed in 1 case. A combination of external rotation and extension was observed in 5 of the 6 cases reporting the mechanism of anterior dislocation. Four cases were successfully treated with closed reduction; 4 required total hip arthroplasty; and 3 required revision capsulorrhaphy.

CONCLUSIONS

Postarthroscopic hip instability was observed in patients with acetabular undercoverage (including iatrogenic resection), labral debridement, capsular insufficiency, or iliopsoas tenotomy. Most dislocations were anterior, occurring with hip extension and external rotation.

LEVEL OF EVIDENCE

Level IV, systematic review of Level IV studies.

Radiographic Evidence of Hip Microinstability in Elite Ballet

PURPOSE

To determine prevalence, magnitude, and predisposing radiographic features of hip subluxation in elite ballet dancers.

METHODS

A cross-sectional investigation of professional male and female ballet dancers was performed using 5 plain radiographs. A "splits" anteroposterior (AP) radiograph was performed with legs abducted parallel to the trunk in the coronal plane (splits position; grand écart facial). Hip center position (HCP) was measured on standing AP pelvis and AP pelvis splits views and the difference calculated (subluxation distance) to determine prevalence and magnitude of femoral head subluxation. Student t test compared HCP on AP pelvis and splits radiographs. Pearson correlations were used to correlate splits HCP with radiographic measures of femoroacetabular impingement and dysplasia.

RESULTS

Analyzing 47 dancers (21 men, 26 women; 23.8 ± 5.4 years), mean HCP on standing AP pelvis was 9.39 ± 3.33 mm versus 10.8 ± 2.92 mm on splits radiograph, with mean subluxation distance of 1.41 mm (P = .035). Forty-two dancers' femoral heads translated laterally with splits positioning, and 17 dancers (36%) exhibited a "vacuum sign" (bilateral in 71% of subjects with at least 1 hip vacuum sign). There was strong positive correlation (r = 0.461, P = .001) with splits HCP and alpha angle (Dunn 45°), and moderate negative correlation (r = -0.332, P = .022) with subluxation distance and neck-shaft angle. In men, splits HCP increased as lateral center edge angle (CEA) decreased (r = -0.437, P = .047), as anterior CEA decreased (r = -0.482, P = .027), as Tönnis angle increased (r = 0.656, P = .001), and as femoral head extrusion index increased (r = 0.511, P = .018). In women, there was moderate negative correlation (r = -0.389, P = .049) with subluxation distance and neck-shaft angle.

CONCLUSIONS

Hip subluxation occurs during splits in most professional ballet dancers, with a significantly greater magnitude of subluxation in women than men. Subluxation magnitude increases with increasing alpha angle and decreasing neck-shaft angle. In men, the magnitude increases with severity of dysplasia. Women had subluxation regardless of acetabular morphology but increased subluxation with decreased neck-shaft angle. This provides radiographic support for hip microinstability in elite ballet.

LEVEL OF EVIDENCE

Level IV, diagnostic.

Capsular Management in Hip Arthroscopy

The hip capsule is a highly complex anatomic structure, which influences normal hip motion and biomechanics. A dynamic stabilizing capsular contribution exists in the iliocapsularis and gluteus minimus, among other musculotendinous structures crossing the joint. Variable types and sizes of capsulotomy are necessary to sufficiently visualize and address the bony and soft tissue pathologic source of symptoms. Unrepaired capsulotomies may leave the hip significantly unstable to variable degrees. Capsular closure is a necessary part of a comprehensive arthroscopic hip preservation procedure. Greater titration of the degree of plication may be performed for patients with risk factors for postoperative instability.