What the papers say.

The Journal of Hip Preservation Surgery (JHPS) is not the only place where work in the field of hip preservation can be published. Although our aim is to offer the best of the best, we are continually fascinated by work, which finds its way into journals other than our own. There is much to learn from it, and so JHPS has selected six recent and topical subjects for those who seek a summary of what is taking place in our ever-fascinating world of hip preservation. What you see here are the mildly edited abstracts of the original articles, to give them what JHPS hopes is a more readable feel. If you are pushed for time, what follows should take you no more than 10 min to read. So here goes …

POSTOPERATIVE, BUT NOT PREOPERATIVE COVID-19 IS ASSOCIATED WITH AN INCREASED RATE OF MEDICAL ADVERSE EVENTS FOLLOWING ARTHROSCOPIC PROCEDURES

The authors from United States and Canada [1] have carried out this study to characterize how severe acute respiratory syndrome coronavirus-2 infection in the perioperative period affects the medical adverse event (MAE) rates in arthroscopic sports medicine procedures. The Mariner corona virus disease 2019 (COVID-19) database was queried for all shoulder, hip or knee arthroscopies, 2010–2020. Patients with COVID-19 in the 3 months before to 3 months after their surgery were matched by age, gender, and Charlson Comorbidity Index to patients with an arthroscopy but no perioperative COVID-19 infection, or a COVID-19 infection but no arthroscopic procedure. MAEs in the 3 months after surgery or illness were compared between groups.

Their final cohort consisted of 1299 matched patients in three groups: COVID alone, arthroscopy and perioperative COVID-19, and arthroscopy alone. There were 265 MAEs if a patient had COVID alone (20.4%), 200 MAEs if a patient had arthroscopy with COVID (15.4%), and 71 (5.5%) MAEs if a patient had arthroscopy alone. If a patient had an arthroscopy, having COVID was associated with 3.1-fold elevated odds of MAE. Among patients with an arthroscopy, MAEs were more common if a patient acquired COVID-19 in the 3 months after their surgery (pooled OR = 7.39, 95% CI 5.49–9.95), but not if a patient had preoperative COVID-19 (pooled OR = 0.66, 95% CI 0.42–1.03).

The authors thus concluded that having COVID-19 during the postoperative period appears to confer a 7-fold elevated risk of MAEs after shoulder, hip and knee arthroscopy compared to matched patients with arthroscopy and no perioperative COVID, but equivalent to that of patients with COVID and no arthroscopy. However, there was no increase in postoperative MAEs if a patient had COVID-19 during the 3 months preceding surgery. Therefore, it appears safe to conduct an arthroscopic procedure shortly after recovery from COVID-19 without an increase in acute medical complication rates.

HANDLE WITH CARE: THE ANTERIOR HIP CAPSULE PLAYS A KEY ROLE IN DAILY HIP PERFORMANCE

In this paper, Duquesne et al. [2] note that passive energy storage and return has long been recognized as one of the central mechanisms for minimizing the energy cost needed for terrestrial locomotion. Although the iliofemoral ligament (IFL) is the strongest ligament in the body, its potential role in energy-efficient walking remains unexplored.

The authors aimed to identify the contribution of the IFL to the amount of work performed by the hip muscles for normal, straight-level walking in this controlled laboratory study.

Straight-level walking of 50 healthy and injury-free adults was simulated using the AnyBody Modeling System. For each participant, the bone morphology and soft tissue properties were non-uniformly scaled. The superior and inferior parts of the IFL were represented by two springs each, and a linear force-strain relation was defined. A parameter study was conducted to account for the uncertainty surrounding the mechanical properties of the IFL. The work required from the gluteus, quadriceps, iliopsoas and sartorius with and without inclusion of the IFL was calculated. Analysis of variance with subsequent post hoc paired t test was used to test the significance of IFL presence on the required mechanical work.

They found that during walking, the strain in the IFL reached a median of 18.7% (95% CI, 8.0–26.5%), with the largest values obtained at toe-off. With the IFL undamaged and fully operational, the effort required by the hip flexor muscles was reduced by a median of 54% (99% CI, 45–62%) for the iliopsoas and by a median of 41% (99% CI, 27–54%) for the sartorius muscles. The inclusion of the IFL did not significantly alter the work required by the gluteus and the quadriceps.

In their conclusion, the authors felt that the findings emphasized the key role the IFL plays in hip flexion by working synergistically with the hip musculature. The importance of the contribution of the IFL to the hip flexors warrants careful handling and repair of these ligaments in cases of surgery and structural damage.

OUTCOME-AFFECTING PARAMETERS OF HIP ARTHROSCOPY FOR FEMOROACETABULAR IMPINGEMENT WITH CONCOMITANT CARTILAGE DAMAGE—DATA ANALYSIS FROM THE GERMAN CARTILAGE REGISTRY

The researchers from Germany [3] aim to report on a prospectively collected, multicenter database of patients undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS) and concomitant cartilage damage (according to the International Cartilage Repair Society) and to assess the outcome-affecting parameters. In the study, 353 hips with up to 24-month follow-up were assessed by iHOT-33 scores and achievement of the minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) levels. Multiple and binary regression analyses were performed to identify factors related to (un-)favorable outcomes and to assess their clinical relevance with regard to achieving the MCID and PASS. Multiple regression yielded the parameters of male sex and lower body mass index (BMI) at 6 months, lower BMI and younger age at 12 months, and younger age at 24 months to be significantly associated with higher iHOT scoring. Male sex and lower BMI were significantly correlated with achievement of the PASS in binary regression at 6 months, whereas at 12 and at 24 only younger age was shown to be significantly correlated. None of the parameters was statistically associated with achievement of the MCID. The authors noted that as the parameters of younger age, male sex, and lower BMI were identified as temporarily correlated with a preferable outcome in general and with achievement of the PASS in particular. The authors felt that these findings will help to pre-operatively identify factors associated with (un-)favorable therapy results.

ACETABULAR RETROVERSION DOES NOT AFFECT OUTCOME IN PRIMARY HIP ARTHROSCOPY FOR FEMOROACETABULAR IMPINGEMENT

In this study Dippmann et al. [4] from Denmark note that the surgical treatment of FAIS in patients with acetabular retroversion (AR) is arthroscopic or by a reverse periacetabular osteotomy. The purpose of their study was to investigate the results after arthroscopic treatment of FAIS in patients with and without radiographic signs of AR in a large, prospective cohort from the Danish Hip Arthroscopy Registry (DHAR). The hypothesis was that there is no difference in clinical outcome between the two groups.

They collected data on 4914 hip arthroscopies performed during 2012–19 from DHAR. Patients with radiographic signs of osteoarthritis (Tönnis > 1), hip dysplasia (CEA < 25°), other hip pathologies or previous hip surgery were excluded. The clinical outcomes for patients with AR [defined by a positive posterior wall sign (PWS) in combination with a positive Ischial Spine Sign (ISS)] and patients without AR (no PWS, no ISS) were analyzed at 1 and 2 years after surgery. The primary outcomes were the six domains of the Copenhagen Hip and Groin Outcome score (HAGOS), while secondary outcomes were the Hip Sports Activity Scale (HSAS), a visual analog pain scale (VAS) and a numeric rating scale (NRS) for pain.

The authors included a total of 3135 hip arthroscopies, of which 339 had AR, 1876 did not, and 920 presented one of the two signs (PWS and ISS). There were no statistically significant differences 1 and 2 years after surgery (n.s.) between patients with and without AR in HAGOS domain scores, HSAS, VAS or NRS. Both groups showed improvement at both follow-ups. The two groups did not differ in relation to intraoperative findings and the procedures they have had.

The Danish researchers reported that the outcome at 1 and 2 years after arthroscopic treatment of FAIS is not different for patients with and without AR.

MIDTERM OUTCOMES AFTER HIP LABRAL AUGMENTATION IN REVISION HIP ARTHROSCOPY

The authors from Vale, Colorado, USA [5], describe that labral augmentation has emerged as an essential procedure to address a deficient or irreparable labrum while preserving native labral tissue and restoring the hip suction seal mechanism.

The purpose of their study was to evaluate midterm outcomes of arthroscopic hip labral augmentation for labral insufficiency after previous hip arthroscopy. Study design was that of case series.

The authors identified patients from a prospectively collected database who underwent arthroscopic hip labral augmentation between January 2011 and January 2017 with a minimum 3-year follow-up. Pre- and postoperative patient-reported outcome scores were compared and included the 12-Item Short Form Health Survey physical and mental component summaries, Western Ontario and McMaster Universities Osteoarthritis Index, modified Harris Hip Score (mHHS) and Hip Outcome Score (HOS) [Activities of Daily Living (ADL) and Sport]. Postoperative Tegner Activity Scale and patient satisfaction (1–10) scores were also evaluated. The minimal clinically important difference (MCID) and Patient Acceptable Symptom State (PASS) between the preoperative and minimum 3-year follow-up scores were calculated.

They reported a total of 88 patients (39 men, 49 women) who underwent revision hip arthroscopy with labral augmentation. The average age was 32.8 years. Of these, 77 patients (88%) were available for the minimum 3-year follow-up. The survivorship (absence of conversion to total hip arthroplasty) at 3 years and 5 years was 93% at both time points, with a mean survival time of 8.5 years (95% CI, 8.0–8.9). Eleven patients (14%) required revision arthroscopic surgery for continued pain. Revisions occurred at a mean of 2.6 years after augmentation. The mean follow-up was 5.2 (range, 3–9 years). For patients not requiring subsequent surgery (n = 61), all patient-reported outcome measures significantly improved, which included a 20-point increase in HOS-ADL (MCID, 82%; PASS, 72%) and mHHS (MCID, 78%; PASS, 70%). The median postoperative Tegner score was 4 (range, 1–10). The median postoperative patient satisfaction score was 9 out of 10 (range, 1–10).

The authors thus concluded that the arthroscopic hip labral augmentation is a successful treatment option for patients with labral insufficiency after previous hip arthroscopy, demonstrating improved patient-reported outcomes and survivorship of 93% at 3 years and 5 years. This technique provides a valuable labral preservation option when addressing hip labral pathology when viable native labral tissue remains.

THE BIOMECHANICAL CONSEQUENCES OF ARTHROSCOPIC HIP CAPSULOTOMY AND REPAIR IN POSITIONS AT RISK FOR DISLOCATION

The authors from New York, USA [6], explore the effect of interportal (IP) capsulotomy, short T-capsulotomy, and long T-capsulotomy, and their repairs, on resistance to anterior and posterior “at risk for dislocation” positions, which has not been quantified.

Their primary hypothesis was that an IP capsulotomy would have a minimal effect on hip resistive torque compared with both short and long T-capsulotomies in the at-risk dislocation positions. Their secondary hypothesis was that capsule repair would significantly increase hip resistive torque for all capsulotomies. They conducted a controlled laboratory study.

Researchers mounted 10 cadaveric hips on a biaxial test frame in an anterior dislocation high-risk position (20° of hip extension and external rotation) and posterior dislocation high-risk position (90° of hip flexion and internal rotation). An axial force of 100 N was applied to the intact hip while the femur was internally or externally rotated at 15° per second to a torque of 5 N· m. The rotatory position at 5 N· m was recorded and set as a target for each subsequent condition. Hips were then sequentially tested with IP, short T- and long T-capsulotomies and with corresponding repairs randomized within each condition. Peak resistive torques were compared using generalized estimating equation modeling and post hoc Bonferroni-adjusted tests.

The authors reported that for the anterior position, the IP and long T-capsulotomies demonstrated significantly lower resistive torques compared with intact. For the posterior position, both the short and the long T-capsulotomies resulted in significantly lower resistive torques compared with intact. Repairs for all 3 capsulotomy types were not significantly different from the intact condition at anterior and posterior positions.

They concluded that an IP incision resulted in a decrease in capsular resistive torque in the anterior but not the posterior at-risk dislocation position, in which direction only T-capsulotomies led to a significant decrease. All capsulotomy repair conditions resulted in hip resistive torques that were similar to the intact hip in both dislocation positions. The authors noted that their results suggest that it was biomechanically advantageous to repair IP, short T- and long T-capsulotomies, particularly for at-risk anterior dislocation positions.