Use of Machine Learning to Predict Improvement After Hip Arthroscopy
The management of expectations is crucial when counseling patients undergoing treatment for a musculoskeletal injury or condition. In hip arthroscopy, this is especially critical when discussing with patients—including athletes seeking to return to play—their anticipated outcomes following surgical treatment for femoroacetabular impingement syndrome (FAIS).
In the latest issue of JBJS, Kunze et al. report on their investigative efforts to develop and internally validate machine learning algorithms that can yield patient-specific predictions of which athletes will reach clinically relevant improvement in function after arthroscopy for FAIS.
A total of 1,118 athletes, identified through a retrospective review of clinical registry data, met the inclusion criteria. The primary outcome was attaining the minimal clinically important difference (MCID) in the Hip Outcome Score-Sports Subscale (HOS-SS) at a minimum of 2 years postoperatively. Six machine learning algorithm models were tested.
The authors found that 23.1% of the athletes did not achieve the MCID for the HOS-SS. Six variables optimized algorithm performance, with the following cutoffs found to decrease the likelihood of achieving the MCID:
- Preoperative HOS-SS score of ≥58.3
- Tönnis grade of 1 (early osteoarthritis)
- Alpha angle of ≥67.1° on anteroposterior radiograph
- Body mass index (BMI) of >26.6 kg/m2
- Tönnis angle of >9.7° (indicating subtle instability or dysplasia)
- Patient age of >40 years
The elastic-net penalized logistic regression (ENPLR) model was the most accurate model in this study.
The findings suggest that patient selection is paramount to the ability to achieve clinically relevant improvements in outcomes for patients treated with arthroscopy for FAIS. Multiple studies have demonstrated that increasing arthritis level and age, along with BMI, are associated with inferior patient-reported outcomes. In addition, hip instability and increased Tönnis angle have been shown to be associated with worse outcomes following hip arthroscopy. A greater alpha angle indicates a larger “deformity” and thus the potential for more damage at the time of surgery that cannot be completely addressed with today’s surgical techniques. “Higher” preoperative HOS-SS (although on a scale of 0 to 100, 58 is not that high) may make it more difficult for a patient to achieve enough of an improvement in their outcome score to be considered as having attained the MCID.
The ENPLR model was converted into an open-source application, although as Kunze et al. point out, external validation is necessary before wider adoption of the application. Nonetheless, the model demonstrates the potential to help hip surgeons better educate our patients on expected outcomes and to assist with proper patient selection for the ever-evolving treatment of FAIS.
Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media
Co-author Kyle N. Kunze, MD discusses this study in an “Author Insights” video, found here.
What’s New in Sports Medicine 2021
Every month, JBJS publishes a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 14 subspecialties. Click here for a collection of all such OrthoBuzz Guest Editorial summaries.
This month, co-author Rachel M. Frank, MD summarizes the 5 most compelling findings from the >30 studies highlighted in the April 21, 2021 “What’s New in Sports Medicine.”
Anterior Cruciate Ligament (ACL)
–Two-year results from the STABILITY randomized controlled trial (RCT)1 comparing single-bundle, hamstring-autograft ACL reconstruction with or without lateral extra-articular tenodesis demonstrated a
4% graft failure in the tenodesis group versus 11% in the non-tenodesis group. Both groups had similar levels of sports activity at 2 years.
Meniscus
–A matched cohort comparison of 45 posterior medial meniscal root tears2 treated either nonoperatively, with partial meniscectomy, or with root repair found the following at a mean of 74 months:
- No significant between-group differences in patient-reported outcomes (IKDC and Tegner scores)
- Progression to arthroplasty in 60% of those who underwent partial meniscectomy, 27% of those treated nonoperatively, and 0% of those who underwent root repair
- Less arthritic progression on radiographs in the root-repair group relative to the other 2 groups
Rotator Cuff
–A multicenter Level-II study compared 96 patients with a rotator cuff tear who underwent nonoperative treatment with 73 similar patients who underwent a surgical procedure. At approximately 3 months, patients in the nonoperative group had significantly better outcomes, but after 1 to 2 years, surgical patients did better in terms of ASES and SPADI scores.
Hip Preservation
–A meta-analysis of 3 RCTs (n=650 patients)3 comparing physical therapy with hip arthroscopy for treating femoroacetabular impingement found the following:
- Greater improvement in the arthroscopy group (as measured with the International Hip Outcome Tool-33) at 10 months
- No between-group differences in 1 of the 3 RCTs at 1 or 2 years when the Hip Outcome Score-ADL and -Sports scales were used
The authors concluded that “hip arthroscopy had significantly superior short-term outcomes.”
Long Head of the Biceps Tendon
–A prospective RCT4 compared biceps tenodesis with biceps tenotomy in >100 patients with pathology of the long head of the biceps tendon. At the 2-year follow-up, the authors found no between-group differences in cramping, elbow flexion strength, or supination strength. The only significant difference was the incidence of a cosmetic Popeye deformity, which was associated with a 3.5 times higher risk after tenotomy.
References
- Getgood AMJ, et al. for the STABILITY Study Group. Lateral extra-articular tenodesis reduces failure of hamstring tendon autograft anterior cruciate ligament reconstruction: 2-year outcomes from the STABILITY study randomized clinical trial. Am J Sports Med.2020 Feb;48(2):285-97. Epub 2020 Jan 15.
- Bernard CD, Kennedy NI, Tagliero AJ, Camp CL, Saris DBF, Levy BA, Stuart MJ, Krych AJ. Medial meniscus posterior root tear treatment: a matched cohort comparison of nonoperative management, partial meniscectomy, and repair. Am J Sports Med.2020 Jan;48(1):128-32. Epub 2019 Nov 25.
- Dwyer T, Whelan D, Shah PS, Ajrawat P, Hoit G, Chahal J. Operative versus nonoperative treatment of femoroacetabular impingement syndrome: a meta-analysis of short-term outcomes. 2020 Jan;36(1):263-73.
- MacDonald P, Verhulst F, McRae S, Old J, Stranges G, Dubberley J, Mascarenhas R, Koenig J, Leiter J, Nassar M, Lapner P. Biceps tenodesis versus tenotomy in the treatment of lesions of the long head of the biceps tendon in patients undergoing arthroscopic shoulder surgery: a prospective double-blinded randomized controlled trial. Am J Sports Med.2020 May;48(6):1439-49. Epub 2020 Mar 30.
What’s New in Sports Medicine 2019
Every month, JBJS publishes a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of all OrthoBuzz Specialty Update summaries.
This month, Albert Gee, MD, a co-author of the April 17, 2019 “What’s New in Sports Medicine,” selected the five most clinically compelling findings from among the 30 noteworthy studies summarized in the article.
Anterior Cruciate Ligament (ACL) Reconstruction
–Norwegian researchers randomized 120 patients to undergo either single-bundle or double-bundle ACL reconstruction and followed them for 2 years.1 They found no difference between the 2 techniques in any patient-reported outcome, knee laxity measurements, or activity levels. These results, along with the preponderance of evidence from other comparative trials over the last 5 years, strongly suggest that routine use of 2 bundles to primarily reconstruct a torn ACL adds no clinical benefit over a well-positioned single-bundle reconstruction.
Knee Cartilage Repair
–A randomized study compared long-term patient outcomes after knee cartilage repair using microfracture versus mosaicplasty.2 Included patients had 1 or 2 focal femoral lesions measuring between 2 and 6 cm2. Better outcomes after a minimum of 15 years of follow-up were found in the mosaicplasty group. Although there were only 20 patients in each arm, the Lysholm-score differences between the groups were both clinically important and statistically significant. More patients in the mosaicplasty group than in the microfracture group said they would have the surgery again, knowing their 15-year outcome.
Rotator Cuff
–UK researchers randomized 313 patients with ≥3 months of subacromial pain and an intact rotator cuff who had completed a nonoperative program of physical therapy and injection to 1 of 3 groups: arthroscopic subacromial decompression, diagnostic arthroscopy (“sham” surgery), or no intervention.3 At 6 months and 1 year, all groups demonstrated statistically significant and clinically important improvement, but patient-reported outcome scores were significantly better in both surgical groups compared with the no-treatment group. The data suggest that patients such as these improve over time, regardless of management, but that surgical decompression may offer a slight benefit over nonoperative management because of the placebo effect.
–A randomized controlled trial investigated the effect of a formal preoperative education program (2-minute video plus handout)4 about postoperative narcotic use, side effects, dependence risk, and addiction potential among >130 patients undergoing arthroscopic rotator cuff repair surgery. The education group consumed 33% less narcotic medication at 6 weeks and 42% less at 12 weeks compared with the control group. Among the more than one-quarter of the patients who had used opioids prior to surgery, those randomized to the education group were 6.8 times more likely than controls to discontinue narcotic use during the study period.
Hip Arthroscopy
–A randomized controlled trial of >300 patients compared hip arthroscopy and “best conservative care” for treating femoroacetabular impingement (FAI).5 Only 8% of patients crossed over from conservative care to the surgical group. The mean adjusted difference in iHOT-33 scores at 1 year was 6.8, in favor of hip arthroscopy. However, adverse events were more frequent in the arthroscopy cohort, and a within-trial economic evaluation suggested that hip arthroscopy was not cost-effective compared with conservative care during the 1-year trial period.
References
- Aga C, Risberg MA, Fagerland MW, Johansen S, Trøan I, Heir S, Engebretsen L. No difference in the KOOS Quality of Life Subscore between anatomic double-bundle and anatomic single-bundle anterior cruciate ligament reconstruction of the knee: a prospective randomized controlled trial with 2 years’ follow-up. Am J Sports Med.2018 Aug;46(10):2341-54. Epub 2018 Jul 18.
- Solheim E, Hegna J, Strand T, Harlem T, Inderhaug E. Randomized study of long-term (15-17 years) outcome after microfracture versus mosaicplasty in knee articular cartilage defects. Am J Sports Med.2018 Mar;46(4):826-31. Epub 2017 Dec 18.
- Beard DJ, Rees JL, Cook JA, Rombach I, Cooper C, Merritt N, Shirkey BA, Donovan JL, Gwilym S, Savulescu J,Moser J, Gray A, Jepson M, Tracey I, Judge A, Wartolowska K, Carr AJ; CSAW Study Group. Arthroscopic subacromial decompression for subacromial shoulder pain (CSAW): a multicentre, pragmatic, parallel group, placebo-controlled, three-group, randomised surgical trial. Lancet. 2018 Jan 27;391(10118):329-38. Epub 2017 Nov 20.
- Syed UAM, Aleem AW, Wowkanech C, Weekes D, Freedman M, Tjoumakaris F, Abboud JA, Austin LS. Neer Award 2018: the effect of preoperative education on opioid consumption in patients undergoing arthroscopic rotator cuff repair: a prospective, randomized clinical trial. J Shoulder Elbow Surg.2018 Jun;27(6):962-7. Epub 2018 Mar 26.
- Griffin DR, Dickenson EJ, Wall PDH, Achana F, Donovan JL, Griffin J, Hobson R, Hutchinson CE, Jepson M,Parsons NR, Petrou S, Realpe A, Smith J, Foster NE; FASHIoN Study Group. Hip arthroscopy versus best conservative care for the treatment of femoroacetabular impingement syndrome (UK FASHIoN): a multicentre randomised controlled trial. Lancet. 2018 Jun 2;391(10136):2225-35. Epub 2018 Jun 1.
Arthroscopy Beats PT for FAI at 8 Months
OrthoBuzz occasionally receives posts from guest bloggers. In response to a recent BMJ study, the following commentary comes from Matthew R. Schmitz, MD, FAOA.
Femoroacetabular impingement (FAI) syndrome continues to be a hot topic in the orthopaedic community. The first two decades of this century have seen huge increases in the number of hip arthroscopies performed in the US and UK,1,2 most of those to treat FAI. In the February 7, 2019 issue of BMJ, Palmer et al., reporting on behalf of the Femoroacetabular Impingement Trial (FAIT), published preliminary findings from a multicenter randomized controlled trial comparing arthroscopic hip surgery to activity modification and physiotherapy for symptomatic FAI.3
The trial randomized 222 patients with a clinical diagnosis of FAI into each cohort (110 in the physiotherapy group and 112 in the arthroscopy group). Follow-up assessments were performed by clinicians blinded to the treatment arm, and attempts were made to standardize both interventions. The participants will eventually be followed for 3 years, but this early report evaluated outcomes 8 months after randomization, with follow-up data available for >80% of patients in both groups.
Baseline characteristics with regard to demographics, radiographic findings, and clinical measurements were similar between the two groups. After adjusting for multiple potential confounders, the authors found that the mean Hip Outcomes Score Activities of Daily Living (HOS ADL) was 10 points higher in the arthroscopy group than in the physiotherapy group, exceeding the prespecified minimum clinically important difference (MCID) of 9 points. The MCID was reached in 51% of surgical patients compared to 32% in the therapy cohort. In addition, the patient acceptable symptomatic state (PASS)—defined as a HOS ADL ≥87 points—was achieved in 48% of surgical patients and only 19% of therapy patients. Relative to the physiotherapy group, the arthroscopic group also had better hip flexion and superior results in a variety of commonly used hip patient-reported outcomes scores.
The 8-month data from this study show that there is a real improvement in patient function and reported outcomes from arthroscopic management for FAI. It will be important, however, to follow these patients for the entire 3 years of the FAIT study to show whether these improvements persist. It should also be emphasized that only half of the patients treated with surgical management achieved MCID at the 8-month point. That finding supports what I tell patients in my young-adult hip-preservation clinics, which seems relevant as baseball season starts: There are rarely any home runs in arthroscopic hip surgery. There are mainly singles and doubles that we hope to stretch into doubles and triples. Still, it appears that even those base hits with arthroscopic surgery are better than the physiotherapy alternative—at least in the early innings of the game.
Matthew R. Schmitz, MD, FAOA is an orthopaedic surgeon specializing in adolescent sports and young adult hip preservation at the San Antonio Military Medical Center in San Antonio, TX. He is also a member of the JBJS Social Media Advisory Board.
References
- Maradit Kremers H, Schilz SR, Van Houten HK et al. Trends in Utilization and Outcomes of Hip Arthrocopy in the United States Between 2005 and 2013. J Arthroplasty 2017; 32:750-5.
- Palmer AJ, Malak TT, Broomfield J, et al. Past and projected temporal trends in arthroscopic hip surgery in England between 2002 and 2018. BMJ Open Sport Exerc Med 2016;2:e000082
- Palmer AJ, Gupta VA, Fernquest S, et al. Arthroscopic hip surgery compared with physiotherapy and activity modification for the treatment of symptomatic femoroacetabular impingement: multicenter randomized controlled trial. BMJ 2019; 364:l185
PAO Results Hold Up over Intermediate Term
The Bernese periacetabular osteotomy (PAO) has become the procedure of choice for treating symptomatic acetabular dysplasia. But how long-lasting are its benefits? Quite, according to one of the largest intermediate-term follow-up studies on this procedure, authored by Wells et al. in the February 7, 2018 edition of The Journal of Bone & Joint Surgery.
Among 154 hips (average patient age of 26 years) treated with PAO at a single center between 1994 and 2008, the survival rate, with total hip arthroplasty (THA) as the endpoint, was 92% at 15 years postoperatively. When failure was defined as a conversion from PAO to THA or a symptomatic hip, the hip-preservation rate was 79% at a mean follow-up of 10.3 years.
After carefully analyzing the data to identify factors that contributed to failure or success, the authors discovered that:
- Hips with fair or poor joint congruency before surgery had 9 times the odds of failing when compared with hips that had good or excellent preoperative joint congruency.
- Hips with a postoperative lateral center-edge angle of >38° had 8 times the odds of failure.
- Hips that underwent a concurrent head-neck osteochondraplasty at the time of PAO had a 73% decrease in the odds of failing.
These data suggest that preventing excessive femoral head coverage and secondary impingement resulting from surgery improves hip survival. Consequently, Wells et al. reported that their institution, Washington University School of Medicine, “currently assess[es] for secondary impingement intraoperatively following PAO,…and, if it is present, osteochondroplasty of the head-neck junction is performed to relieve potential secondary femoroacetabular impingement.”
The authors also recommend against managing patients with symptomatic acetabular dysplasia with hip arthroscopy because “it fails to address the underlying pathomechanics found in developmental dysplasia of the hip.”
Where Does the Blood Flow in the Femoral Head?
Osseous vascular anatomy has always been clinically relevant to orthopaedists, but its importance is sometimes overlooked. In the July 19, 2017 issue of The Journal, Rego et al. provide a precise topographic map of arterial anatomy in and around the femoral head.
Ever since Trueta’s classic work published in the British volume of JBJS in 1953, we’ve known that the terminal branches of the medial femoral circumflex system (also known as the lateral epiphyseal artery complex) supply blood to the majority of the femoral head. This information has proved critical in supporting treatment decisions for the management of femoral head and neck fractures. In those cases, surgeons typically perform ORIF through an anterior approach because it is remote from this posterior vascular supply.
The details in the Rego et al. study will help today’s and tomorrow’s arthroscopists more safely manage acetabular labral tears associated with cam deformities. In those settings, when increasing the “offset” across the femoral neck to decrease impingement, surgeons should limit the depth of bone removal to avoid injury to this important vascular network. Thanks to this study, operating surgeons now have precise anatomic information (albeit derived from non-deformed cadaver hips) with which to limit the risks of increasing the femoral head offset.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
The Acetabulum’s Role in SCFE: Cause or Consequence?
The multifactorial pathogenesis of slipped capital femoral epiphysis (SCFE) almost certainly involves the acetabulum, but previous studies about that relationship have been inconclusive. In the June 21, 2017 issue of JBJS, Hesper et al. report on a matched-cohort study that used precise measurements gleaned from CT to determine that acetabular retroversion—not acetabular depth or overcoverage of the femoral head—is associated with SCFE.
The authors carefully measured acetabular depth, head coverage, and retroversion in three groups of hips: the affected hips of 36 patients with unilateral SCFE, the unaffected contralateral hips of those same patients, and healthy hips of 36 age- and sex-matched controls. They observed no deep acetabula or acetabular overcoverage in the SCFE-affected hips, but they did find a lower mean value for acetabular version (i.e., retroversion) at the level of the femoral-head center in the SCFE-affected hips, relative to contralateral and control hips. The acetabulum was retroverted cranially in cases of severe SCFE compared with mild and moderate cases.
These findings support the hypothesis that SCFE-affected hips have reduced acetabular version, but the authors note that “additional studies will be necessary to determine whether acetabular retroversion is a primary morphological abnormality associated with the mechanical etiology of SCFE, or if it is an adaptive response to the acetabulum after the slip.” Either way, Hesper et al. conclude that their data “may help with planning treatment for patients with residual pain and limited motion related to femoroacetabular impingement after SCFE.
Does Hip Arthroscopy Really Help?
Over the past 15 to 20 years, the use of arthroscopic procedures for hip pathologies has rapidly increased. Leaders in sports medicine have standardized many arthroscopic techniques, including methods of joint distraction, portal location, approaches to labral repair or debridement, and management of cartilage lesions.
Many in the orthopaedic community have wondered whether this expansive use of hip arthroscopy is justified by significant improvement in patient function or is simply a first (and perhaps overused) step toward inevitable hip arthroplasty. To help answer that question, in the June 21, 2017 issue of The Journal, Menge et al. document the 10-year outcomes of arthroscopic labral repair or debridement in 145 patients who originally presented with femoroacetabular impingement (FAI).
Whether these patients were treated with debridement or repair, their functional outcomes and improvement in symptoms were excellent over the 10-year time frame, and the median satisfaction score (10) indicates that these patients were very satisfied overall. However, as seen in other similar studies in the peer-reviewed literature, the results in older patients with significant cartilage injury or radiographic joint space narrowing were inferior, and most of the patients with these characteristics ended up with a hip replacement.
The Menge et al. study helps confirm that arthroscopic repair or debridement in well-selected FAI patients yields excellent longer-term outcomes, and it provides concrete criteria for patient selection.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
Plusses and Minuses of Capital Femoral Growth Plate Extension
Femoroacetabular impingement (FAI), especially in adolescent athletes, has received a lot of attention from orthopaedists in the last 15 years. In the May 18, 2016 edition of The Journal of Bone & Joint Surgery, a longitudinal radiographic study by Morris et al. sheds light on how a measurement called the epiphyseal extension ratio (EER) delivers excellent diagnostic accuracy for predicting cam morphology of the femoral head, one of the main causes of FAI.
The authors carefully analyzed at least five consecutive annual hip radiographs from 96 healthy adolescents. Specifically, they measured changes in the anteroposterior alpha angle and the superior EER (the superior epiphyseal extension divided by the femoral head diameter). They found a mean increase in alpha angle and EER between Oxford bone age (OBA) stages 5 and 7/8. The mean EER increased significantly at each stage, with the greatest increase occurring between OBA stages 6 and 7/8.
In this study, the EER showed excellent diagnostic accuracy for predicting a final alpha angle of ≥78, which prior research has suggested is a threshold that predicts an increased risk for developing end-stage hip osteoarthritis. However, as commentator John H. Wedge, MD emphasizes, Morris et al. “do not recommend radiographic screening for this marker.”
Dr. Wedge adds that this study lends credence to the hypothesis that cam deformity develops from chronic impingement before rather than after proximal femoral physeal closure. But perhaps the most interesting messages are in the discussion section, where Morris et al. state that “epiphyseal extension may be a physiologic, protective response to increased physeal shear forces that decreases the risk of progression to SCFE [slipped capital femoral epiphysis].” The authors describe the cam-morphology downside of epiphyseal extension as “the unfortunate long-term consequence of a short-term adaptive response.”
JBJS Editor’s Choice—Prevent Nerve Damage During Anterior Hip Approaches
While anatomy is the foundation of all surgical practice, we at The Journal do not often publish an-
atomic manuscripts. We make exceptions when papers have the potential to influence the practice of orthopaedic surgery in a major way. Such an exception is the cadaver study by Rudin et al. in the April 6, 2016 JBJS.
The authors focus on the course of the lateral femoral cutaneous nerve (LFCN) of the thigh. This is a highly relevant anatomic structure because of the increasing interest in the anterior approach for hip arthroplasty, for anterior approaches to the hip for open reduction of femoral-head or proximal-femur fractures, and even for surgically treating femoroacetabular impingement.
The major take-home point is the extensive variability of this nerve in terms of where it exits the pelvis and its three different branching patterns from there (see illustration). These anatomic findings should alert the operating surgeon to make skin incisions as lateral as possible and to take extra caution when creating the interval deep to the fascial plane.
Rudin et al. have performed a service to the orthopaedic community by carefully defining the high degree of variability in the course of this nerve, which often is in harm’s way during common surgical exposures. Although injury to the sensory-only LFCN will not lead to major neurological complications, the authors conclude that patients undergoing anterior hip approaches should be informed of the risks of sensory loss or dysesthesia.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
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