Surgical hip dislocation does not result in atrophy or fatty infiltration of periarticular hip muscles

Hip Abductor Deficiency after Total Hip Arthroplasty: Diagnostic and Therapeutic Methods

Abductor deficiency after total hip arthroplasty is a severe complication with functional limitations and a significant reduction in the patient's quality of life. Common causes are degenerative ruptures or approach-related iatrogenic damage to the gluteus medius and minimus muscle and the inferior gluteal nerve, fractures of the greater trochanter and incorrect reconstruction of leg length and femoroacetabular offset. With a standardised diagnosis consisting of a clinical examination, conventional X-ray and MRI, the causes of the functional problems can often be reliably determined. Therapy of abductor deficiency is challenging for both patients and physicians and is often tedious. However, with a clear diagnostic and therapeutic algorithm and straightforward patient education, good treatment results can be achieved even in this challenging condition. Conservative therapy with eccentric stretching and muscle strengthening are the basis of the treatment. In cases of progression of complaints despite intensive conservative treatment, various anatomical and extra-anatomical surgical reconstruction methods are available to relieve pain and improve function. Anatomical reconstruction of the gluteal tendon insertion is an option in cases of low-grade fatty infiltration and moderate retraction of the gluteal muscles. In situations with advanced degenerative changes in the gluteus medius and minimus muscles and an intact gluteus maximus muscle, transfer of the anterior portion of the gluteus maximus according to Whiteside is an option. For high-grade defects of the soft tissue, there is also the option of an isolated or combined transfer of the vastus lateralis muscle.

Surgical hip dislocation with relative femoral neck lengthening and retinacular soft-tissue flap for sequela of Legg–Calve–Perthes disease

Objective

Correction of post-LCP (Legg–Calve–Perthes) morphology using surgical hip dislocation with retinacular flap and relative femoral neck lengthening for impingent correction reduces the risk of early arthritis and improves the survival of the native hip joint.

Indications

Typical post-LCP deformity with external and internal hip impingement due to aspherical enlarged femoral head and shortened femoral neck with high riding trochanter major without advanced osteoarthritis (Tönnis classification ≤ 1) in the younger patient (age < 50 years).

Contraindications

Advanced global osteoarthritis (Tönnis classification ≥ 2).

Surgical technique

By performing surgical hip dislocation, full access to the hip joint is gained which allows intra-articular corrections like cartilage and labral repair. Relative femoral neck lengthening involves osteotomy and distalization of the greater trochanter with reduction of the base of the femoral neck, while maintaining vascular perfusion of the femoral head by creation of a retinacular soft-tissue flap.

Postoperative management

Immediate postoperative mobilization on a passive motion device to prevent capsular adhesions. Patients mobilized with partial weight bearing of 15 kg with the use of crutches for at least 8 weeks.

Results

In all, 81 hips with symptomatic deformity of the femoral head after healed LCP disease were treated with surgical hip dislocation and offset correction between 1997 and 2020. The mean age at operation was 23 years; mean follow-up was 9 years; 11 hips were converted to total hip arthroplasty and 1 patient died 1 year after the operation. The other 67 hips showed no or minor progression of arthrosis. Complications were 2 subluxations due to instability and 1 pseudarthrosis of the lesser trochanter; no hip developed avascular necrosis.

A new classification system for evaluating fatty infiltration of the gluteus minimus in hip osteoarthritis using plain computed tomography

BACKGROUND

Fatty infiltration of the gluteus muscles increases due to the presence of hip osteoarthritis (OA); it is often evident in the gluteus minimus. The gluteus minimus acts not only as an abductor and rotator but also helps stabilize the femur's head. Moreover, the atrophy or fatty infiltration of the gluteus minimus leads to an increased risk of fall and fracture. Until now, fatty infiltration of this muscle has often been evaluated using magnetic resonance imaging using the Goutallier classification system, originally developed for the rotator cuff. However, the accessibility of magnetic resonance imaging remains problematic, and the reliability of the classification has room for improvement. Thus, this study aimed to devise a new classification system for the fatty infiltration of the gluteus minimus using plain computed tomography (CT).

METHODS

We retrospectively reviewed 71 patients (141 hips) who underwent unilateral total hip arthroplasty for hip OA. To assess the system's reliability, three doctors classified the fatty infiltration of the gluteus minimus based on the CT images of 20 hips randomly selected from the study participants using both the Goutallier and the new classification systems. Then, we selected 113 hips with Crowe type 1 and evaluated them using the new classification system to assess the association between the extent of fatty infiltration and the severity of hip OA.

RESULTS

Both classifications had good intra- and inter-observer reliability. The kappa values of the new classification system (0.83-0.95) were higher than that of the Goutallier classification system (0.72-0.87). The Jonckheere-Terpstra test showed that the degree of fatty infiltration of the gluteus minimus according to the new system progressed incrementally with the progression of hip OA (p = 0.016).

CONCLUSIONS

The new classification system can be recommended for clinical use.

Postoperative Musculoskeletal Imaging and Interventions Following Hip Preservation Surgery, Deformity Correction, and Hip Arthroplasty

Total hip arthroplasty and hip preservation surgeries have substantially increased over the past few decades. Musculoskeletal imaging and interventions are cornerstones of comprehensive postoperative care and surveillance in patients undergoing established and more recently introduced hip surgeries. Hence the radiologist's role continues to evolve and expand. A strong understanding of hip joint anatomy and biomechanics, surgical procedures, expected normal postoperative imaging appearances, and postoperative complications ensures accurate imaging interpretation, intervention, and optimal patient care. This article presents surgical principles and procedural details pertinent to postoperative imaging evaluation strategies after common hip surgeries, such as radiography, ultrasonography, computed tomography, and magnetic resonance imaging. We review and illustrate the expected postoperative imaging appearances and complications following chondrolabral repair, acetabuloplasty, osteochondroplasty, periacetabular osteotomy, realigning and derotational femoral osteotomies, and hip arthroplasty.

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

BACKGROUND

Periacetabular osteotomy (PAO) is a common treatment for pre-arthritic hip dysplasia in young adults. The purpose of this study was to better understand changes in muscle volume and composition after PAO visualized using magnetic resonance imaging (MRI).

METHODS

A prospectively collected series of individuals that underwent PAO for hip dysplasia were reviewed to identify subjects with pre- and postoperative MRI. In our practice, MRI was obtained preoperatively and greater than 6 months after PAO for persistent hip pain. MRI sequences were selected to optimize visualization of the muscle volume, fatty infiltration, and hip joint cartilage. MRI images were selected at predetermined bony landmarks and analyzed using 3D Slicer (©2021, www.slicer.org) software to measure muscle diameter and calculate muscle cross-sectional area (CSA) in 17 individual muscles surrounding the hip. Muscle atrophy was graded using the Goutallier classification for fatty infiltration and acetabular cartilage condition was graded using the Outerbridge classification. We compared pre- and postoperative muscle area and composition as well as cartilage for each case.

RESULTS

A series of six female patients met our inclusion criteria. Mean age was 26 years at time of surgery. All cases had MRI sequences adequate for muscle volume measurements. Fatty infiltration and cartilage changes were recorded in four subjects with appropriate MRI sequences. Separating muscle groups, external rotators underwent the largest volume increase. Hip flexors demonstrated mild volume decrease. CSA change among external rotators averaged +12%, hip flexors -9.3%, and hip abductors -9.2% after PAO. All muscles had either the same or increased fatty infiltration after surgery, with gluteus medius and iliacus undergoing the most average increase. Similarly, cartilage condition worsened by a small margin in this series.

CONCLUSION

Our results provide preliminary indication that PAO may have noticeable effects on muscle characteristics and cartilage in the early postoperative period. This was a limited case series of subjects with adequate pre- and post-operative MRI imaging.Level of Evidence: IV.

Acetabular Cartilage Thickness Differs Among Cam, Pincer, or Mixed-Type Femoroacetabular Impingement: A Descriptive Study Using In Vivo Ultrasonic Measurements During Surgical Hip Dislocation

OBJECTIVE

To investigate acetabular cartilage thickness among (1) 8 measurement locations on the lunate surface and (2) different types of femoroacetabular impingement (FAI).

DESIGN

Prospective descriptive study comparing in vivo measured acetabular cartilage thickness using a validated ultrasonic device during surgical hip dislocation in 50 hips. Measurement locations included the anterior/posterior horn and 3 locations on each peripheral and central aspect of the acetabulum. The clock system was used for orientation. Thickness was compared among cam (11 hips), pincer (8 hips), and mixed-type (31 hips) of FAI. Mean age was 31 ± 8 (range, 18-49) years. Hips with no degenerative changes were included (Tönnis stage = 0).

RESULTS

Acetabular cartilage thickness ranged from 1.7 mm to 2.7 mm and differed among the 8 locations (P < 0.001). Thicker cartilage was found on the peripheral aspect at 11 and 1 o'clock positions (mean of 2.4 mm and 2.7 mm, respectively). At 5 out of 8 locations of measurement (anterior and posterior horn, 1 o'clock peripheral, 12 and 2 o'clock central), cartilage thickness was thinner in hips with pincer impingement compared to cam and/or mixed-type of FAI (P ranging from <0.001 to 0.031). No difference in thickness existed between cam and mixed-type of impingement (P = 0.751).

CONCLUSION

Acetabular cartilage thickness varied topographically and among FAI types. This study provides first baseline information about topographical cartilage thickness in FAI measured in vivo. Thinner cartilage thickness in pincer deformities could be misinterpreted as joint degeneration and could therefore have an impact on indication for hip preserving surgery.

No difference in flexion power despite iliopsoas fatty degeneration in healed hip fractures with large lesser trochanter displacement

Objective

To evaluate iliopsoas atrophy and loss of function after displaced lesser trochanter fracture of the hip.

Design

Cohort study.

Setting

District hospital.

Patients

Twenty consecutive patients with pertrochanteric fracture and displacement of the lesser trochanter of > 20 mm.

Intervention

Fracture fixation with either an intramedullary nail or a plate.

Outcome measurements

Clinical scores (Harris hip, WOMAC), hip flexion strength measurements, and magnetic resonance imaging findings.

Results

Compared with the contralateral non-operated side, the affected side showed no difference in hip flexion force in the supine upright neutral position and at 30° of flexion (205.4 N vs 221.7 N and 178.9 N vs. 192.1 N at 0° and 30° flexion, respectively). However, the affected side showed a significantly greater degree of fatty infiltration compared with the contralateral side (global fatty degeneration index 1.085 vs 0.784), predominantly within the psoas and iliacus muscles.

Conclusion

Severe displacement of the lesser trochanter (> 20 mm) in pertrochanteric fractures did not reduce hip flexion strength compared with the contralateral side. Displacement of the lesser trochanter in such cases can lead to fatty infiltration of the iliopsoas muscle unit. The amount of displacement of the lesser trochanter did not affect the degree of fatty infiltration.

Level of evidence

II.

[Impingement of the hip]

Femoroacetabular impingement (FAI) describes the repetitive painful contact between the acetabulum, the pelvis and the proximal femur. This bony abutment can lead to a characteristic pattern of chondrolabral damage and is one of the main etiological factors in the development of juvenile osteoarthritis of the hip joint. This article describes the current treatment concepts of FAI and the radiological assessment including an overview of standard measurement methods, coxometric parameters and cut-off values. Furthermore, the authors stress the importance of a profound understanding of the entire configuration of the pelvis and the dynamic interplay of its components.

How Does the dGEMRIC Index Change After Surgical Treatment for FAI? A Prospective Controlled Study: Preliminary Results

BACKGROUND

Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) allows an objective, noninvasive, and longitudinal quantification of biochemical cartilage properties. Although dGEMRIC has been used to monitor the course of cartilage degeneration after periacetabular osteotomy (PAO) for correction of hip dysplasia, such longitudinal data are currently lacking for femoroacetabular impingement (FAI).

QUESTIONS/PURPOSES

(1) How does the mean acetabular and femoral dGEMRIC index change after surgery for FAI at 1-year followup compared with a similar group of patients with FAI treated without surgery? (2) Does the regional distribution of the acetabular and femoral dGEMRIC index change for the two groups over time? (3) Is there a correlation between the baseline dGEMRIC index and the change of patient-reported outcome measures (PROMs) at 1-year followup? (4) Among those treated surgically, can dGEMRIC indices distinguish between intact and degenerated cartilage?

METHODS

We performed a prospective, comparative, nonrandomized, longitudinal study. At the time of enrollment, the patients' decision whether to undergo surgery or choose nonoperative treatment was not made yet. Thirty-nine patients (40 hips) who underwent either joint-preserving surgery for FAI (20 hips) or nonoperative treatment (20 hips) were included. The two groups did not differ regarding Tönnis osteoarthritis score, preoperative PROMs, or baseline dGEMRIC indices. There were more women (60% versus 30%, p = 0.003) in the nonoperative group and patients were older (36 ± 8 years versus 30 ± 8 years, p = 0.026) and had lower alpha angles (65° ± 10° versus 73° ± 12°, p = 0.022) compared with the operative group. We used a 3.0-T scanner and a three-dimensional dual flip-angle gradient-echo technique for the dGEMRIC technique for the baseline and the 1-year followup measurements. dGEMRIC indices of femoral and acetabular cartilage were measured separately on the initial and followup radial dGEMRIC reformats in direct comparison with morphologic radial images. Regions of interest were placed manually peripherally and centrally within the cartilage based on anatomic landmarks at the clockface positions. The WOMAC, the Hip disability and Osteoarthritis Outcome Score, and the modified Harris hip score were used as PROMs. Among those treated surgically, the intraoperative damage according to the Beck grading was recorded and compared with the baseline dGEMRIC indices.

RESULTS

Although both the operative and the nonoperative groups experienced decreased dGEMRIC indices, the declines were more pronounced in the operative group (-96 ± 112 ms versus -16 ± 101 ms on the acetabular side and -96 ± 123 ms versus -21 ± 83 ms on the femoral side in the operative and nonoperative groups, respectively; p < 0.001 for both). Patients undergoing hip arthroscopy and surgical hip dislocation experienced decreased dGEMRIC indices; the decline in femoral dGEMRIC indices was more pronounced in hips after surgical hip dislocation (-120 ± 137 ms versus -61 ± 89 ms, p = 0.002). In the operative group a decline in dGEMRIC indices was observed in 43 of 44 regions over time. In the nonoperative group a decline in dGEMRIC indices was observed in four of 44 regions over time. The strongest correlation among patients treated surgically was found between the change in WOMAC and baseline dGEMRIC indices for the entire joint (R = 0.788, p < 0.001). Among those treated nonoperatively, no correlation between baseline dGEMRIC indices and change in PROMs was found. In the posterosuperior quadrant, the dGEMRIC index was higher for patients with intact cartilage compared with hips with chondral lesions (592 ± 203 ms versus 444 ± 205 ms, p < 0.001).

CONCLUSIONS

We found a decline in acetabular, femoral, and regional dGEMRIC indices for the surgically treated group at 1-year followup despite an improvement in all PROMs. We observed a similar but less pronounced decrease in the dGEMRIC index in symptomatic patients without surgical treatment indicating continuous cartilage degeneration. Although treatment of FAI is intended to alter the forces acting across the hip by eliminating impingement, its effects on cartilage biology are not clear. dGEMRIC provides a noninvasive method of assessing these effects. Longer term studies will be needed to determine whether the matrix changes of the bradytrophic cartilage seen here are permanent or clinically important.

LEVEL OF EVIDENCE

Level II, therapeutic study.

What MRI Findings Predict Failure 10 Years After Surgery for Femoroacetabular Impingement?

BACKGROUND

Magnetic resonance arthrogram (MRA) with radial cuts is presently the best available preoperative imaging study to evaluate chondrolabral lesions in the setting of femoroacetabular impingement (FAI). Existing followup studies for surgical treatment of FAI have evaluated predictors of treatment failure based on preoperative clinical examination, intraoperative findings, and conventional radiography. However, to our knowledge, no study has examined whether any preoperative findings on MRA images might be associated with failure of surgical treatment of FAI in the long term.

QUESTIONS/PURPOSES

The purposes of this study were (1) to identify the preoperative MRA findings that are associated with conversion to THA, any progression of osteoarthritis, and/or a Harris hip score of < 80 points after acetabuloplasty and/or osteochondroplasty of the femoral head-neck junction through a surgical hip dislocation (SHD) for FAI at a minimum 10-year followup; and (2) identify the age of patients with symptomatic FAI when these secondary degenerative findings were detected on preoperative radial MRAs.

METHODS

We retrospectively studied 121 patients (146 hips) who underwent acetabuloplasty and/or osteochondroplasty of the femoral head-neck junction through SHD for symptomatic anterior FAI between July 2001 and March 2003. We excluded 35 patients (37 hips) with secondary FAI after previous surgery and 11 patients (12 hips) with Legg-Calvé-Perthes disease. All patients underwent preoperative MRA to further specify chondrolabral lesions except in 19 patients (32 hips) including 17 patients (20 hips) who presented with an MRI from an external institution taken with a different protocol, 10 patients with no preoperative MRA because the patients had already been operated on the contralateral side with a similar appearance, and two patients (two hips) refused MRA because of claustrophobia. This resulted in 56 patients (65 hips) with idiopathic FAI and a preoperative MRA. Of those, three patients (three hips) did not have minimal 10-year followup (one patient died; two hips with followup between 5 and 6 years). The remaining patients were evaluated clinically and radiographically at a mean followup of 11 years (range, 10-13 years). Thirteen pathologic radiographic findings on the preoperative MRA were evaluated for an association with the following endpoints using Cox regression analysis: conversion to THA, radiographic evidence of any progression of osteoarthritis, and/or a Harris hip score of < 80. The age of the patient when each degenerative pattern was found on the preoperative MRA was recorded.

RESULTS

The following MRI findings were associated with one or more of our predefined failure endpoints: cartilage damage exceeding 60° of the circumference had a hazard ratio (HR) of 4.6 (95% confidence interval [CI], 3.6-5.6; p = 0.003) compared with a damage of less than 60°, presence of an acetabular rim cyst had a HR of 4.1 (95% CI, 3.1-5.2; p = 0.008) compared with hips without these cysts, and presence of a sabertooth osteophyte had a HR of 3.2 (95% CI, 2.3-4.2; p = 0.013) compared with hips without a sabertooth osteophyte. The degenerative pattern associated with the youngest patient age when detected on preoperative MRA was the sabertooth osteophyte (lower quartile 27 years) followed by cartilage damage exceeding 60° of the circumference (28 years) and the presence of an acetabular rim bone cyst (31 years).

CONCLUSIONS

Preoperative MRAs with radial cuts reveal important findings that may be associated with future failure of surgical treatment for FAI. Most of these factors are not visible on conventional radiographs or standard hip MRIs. Preoperative MRA evaluation is therefore strongly recommended on a routine basis for patients undergoing these procedures. Findings associated with conversion to arthroplasty, radiographic evidence of any progression of osteoarthritis, and/or a Harris hip score of < 80 points should be incorporated into the decision-making process in patients being evaluated for joint-preserving hip surgery.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Patients undergoing surgical hip dislocation for the treatment of acetabular fractures show favourable long-term outcome

Aims

The aims of this study were to determine the cumulative ten-year survivorship of hips treated for acetabular fractures using surgical hip dislocation and to identify factors predictive of an unfavourable outcome.

Patients and Methods

We followed up 60 consecutive patients (61 hips; mean age 36.3 years, standard deviation (sd) 15) who underwent open reduction and internal fixation for a displaced fracture of the acetabulum (24 posterior wall, 18 transverse and posterior wall, ten transverse, and nine others) with a mean follow-up of 12.4 years (sd 3).

Results

Clinical grading was assessed using the modified Merle d’Aubigné score. Radiographic osteoarthritis was graded according to Matta. Kaplan-Meier survivorship and a univariate Cox-regression analysis were carried out using the following endpoints: total hip arthroplasty, a Merle d’Aubigné score of < 15 and/or progression of osteoarthritis.

Conclusion

The ten-year cumulative survivorship was 82% (95% confidence interval 71 to 92). Predictors for the defined endpoints were femoral chondral lesions, marginal impaction, duration of surgery, and age of patient. Cite this article: Bone Joint J 2017;99-B:508–15.