Assessment of fatty degeneration of the gluteal muscles in patients with THA using MRI: reliability and accuracy of the Goutallier and quartile classification systems

Preservation of the lateral femoral circumflex artery in total hip arthroplasty using the bikini-type direct anterior approach : effect on muscle status and clinical outcomes

Aims

The direct anterior approach (DAA) is increasing in popularity as a minimally invasive technique for total hip arthroplasty (THA). DAA-THA involves ligation of the ascending branch of the lateral femoral circumflex artery (a-LFCA), considered to contribute to the blood supply of the tensor fasciae latae (TFL) muscle. To determine the morbidity of these surgical steps, periarticular muscle status and clinical outcomes were assessed after bikini-type DAA-THA with a-LFCA preservation versus ligation.

Methods

We evaluated the surgical records of 140 patients undergoing DAA-THA with continuous attempt of a-LFCA preservation from May to October 2021. A total of 92 patients were eligible and 46 consented to study participation (n = 20 preservation, n = 26 ligation). Preoperative and six-week clinical and radiological data were retrospectively extracted from patient files, and patient-reported outcome measures (PROMs) from the institutional registry. Clinical and MRI examinations were performed two years postoperatively to analyze volume and fatty infiltration of the TFL, gluteus medius, and gluteus minimus relative to the contralateral hip. A total of 13 patients underwent contralateral THA and were excluded from the analysis of muscle status.

Results

Coxa valga morphology and less muscular habitus were more frequent in a-LFCA preservation. After a-LFCA preservation, less anterolateral soft-tissue swelling was described at six weeks (p < 0.001) and TFL local pain at two years (p = 0.034) postoperatively. PROMs did not differ between groups. Mean TFL volume side-difference was not significantly different after a-LFCA preservation (p = 0.276), but it was significantly different after ligation (11.6% smaller (SD 15.5); p = 0.022). TFL fatty infiltration side-difference was larger after a-LFCA ligation (p = 0.010). Muscle status of the gluteus medius and minimus did not differ between sides and groups.

Conclusion

a-LFCA preservation had a minor effect on TFL muscle status. Since preservation was primarily feasible in hips with simpler morphology, it remains uncertain whether differences were due to preserved vascularity or reduced TFL injury. Hence, a-LFCA preservation does not appear essential. However, until further evidence becomes available, attempting a-LFCA preservation may be advisable.

The peri-articular muscle envelope of the hip (PAME) shows atrophy in patients with refractory groin pain after iliopsoas tenotomy

BACKGROUND

Iliopsoas tenotomy is commonly used to address refractory groin pain resulting from iliopsoas tendinopathy. However, consensus and high-level research on its effectiveness are lacking, with concerns about poor outcomes and complications. Little is known of the effects of iliopsoas tenotomy on the peri-articular muscle envelope of the hip. As the iliopsoas loses its function as the most important hip flexor, the rectus femoris takes over its function, which makes the rectus prone to tendinopathy.

METHODS

A retrospective review of patients (n = 17) undergoing iliopsoas tenotomy between January 2016 and January 2021 was conducted. Pelvic MRI scans were evaluated for muscle quality and volume using a Quartile classification system and cross-sectional area (CSA) measurements. Reliability tests determined the most consistent reference points. Statistical analyses assessed changes between ipsilateral and contralateral sides.

RESULTS

Following iliopsoas tenotomy, significant reduced cross sectional area was seen in the psoas, iliacus, gluteus minimus, gluteus maximus, rectus femoris, piriformis, obturator internus and obturator externus. Significant increased fatty degeneration was seen in the psoas, iliacus, gluteus minimus, tensor fascia latae, piriformis, obturator internus and obturator externus. The gluteus medius was the only muscle where no difference was seen in the cross sectional area or the fatty degeneration. 15 patients (88%) presented with rectus tendinopathy and 8 of these patients had a surgical debridement of the rectus femoris.

CONCLUSIONS

Our findings reveal that patients with persistent groin pain following iliopsoas tenotomy exhibit changes in the peri-articular muscle envelope, displaying atrophy or fatty degeneration in all muscles except the gluteus medius. Awareness of potential risks is crucial when contemplating iliopsoas tenotomy. Persistent groin pain after iliopsoas tenotomy may be linked to secondary rectus femoris tendinopathy. Caution is recommended in the consideration of iliopsoas tenotomy for patients with pre-existing iliopsoas tendinopathy.

Platelet-rich plasma does not influence magnetic resonance imaging findings of the gluteus muscles after total hip arthroplasty through the Hardinge approach

OBJECTIVE

Total hip arthroplasty through the Hardinge approach damages the hip abductor muscles. MRI can be used to assess adverse postoperative events. In this prospective randomized controlled trial, we evaluated MRI findings and whether platelet-rich plasma affected postoperative healing of the gluteal muscles (gluteus medius and minimus).

MATERIALS AND METHODS

Forty patients with hip osteoarthritis requiring treatment with total hip arthroplasty, aged between 60 and 76 years, were included. Patients were randomized into two groups: 19 patients in the platelet-rich plasma group and 21 in the placebo group. Platelet-rich plasma or placebo was injected into the gluteus medius tendon incision line during closure. Postoperative hip MRI and plain radiographs were taken 3 and 12 months after surgery.

RESULTS

MRI showed fatty atrophy of the gluteal muscles in all 40 patients (100%), gluteal muscle tear in 11 patients (28%), and atrophy in 16 patients (40%) at both 3 and 12 months postoperatively. Fluid collections related to the operated hip joint were seen in 18 patients (45%) at 3 months and 13 patients (33%) at 12 months, heterotopic ossification formation in nine patients (23%) at 3 months, and 12 patients (31%) at 12 months. There were no significant differences in imaging findings between the two groups.

CONCLUSION

MRI can be a valuable tool for evaluating postoperative healing after total hip arthroplasty. Fatty atrophy of the gluteal muscles was a common finding. Platelet-rich plasma injection into the gluteus medius tendon did not improve healing detected by MRI.

Assessment and quantitative analysis of hip surrounding muscles in children with developmental dysplasia of the hip via magnetic resonance imaging

BACKGROUND

The muscles that encase the hip serve a crucial role in both joint stability and functional efficacy, and as developmental dysplasia of the hip (DDH) progresses, the surrounding musculature may undergo specific adaptations that reduce joint stability, thereby exacerbating dislocation. Yet, the exact nature of changes in muscle morphology and quality remains inadequately investigated. This study aimed to compare magnetic resonance imaging (MRI) evaluations of the iliopsoas and other hip flexor and extensor muscles in children with unilateral DDH before and after treatment.

METHODS

Children with unilateral DDH were included in this study and compared to a matched control group. Using T2-weighted MRI sequences, muscle cross-sectional area (CSA) and fat infiltration (FI) were measured for the iliopsoas, sartorius, rectus femoris, tensor fasciae latae, and gluteus maximus. The cross-sectional area ratio (CSAr) was calculated as the CSA of the affected side divided by the CSA of the healthy side, corresponding to the respective sides in normal controls. For long-term follow-up (≥ 5 years), data from DDH children were analyzed, categorized into groups based on treatment. Comparisons of muscle CSAr and FI at the final follow-up were made against preoperative levels.

RESULTS

Preoperative median CSAr values for the iliopsoas, rectus femoris, and gluteus maximus in DDH children were significantly lower than those of the control group (P < 0.001). FI levels were also higher in the DDH group compared to controls. In the closed reduction group, iliopsoas CSAr increased and FI decreased at the final follow-up compared to preoperative measurements. Conversely, in the open reduction group, iliopsoas CSAr and FI decreased. In the Dega osteotomy group, both iliopsoas CSAr and FI decreased, while CSAr for the sartorius, rectus femoris, and gluteus maximus increased, with also reduced FI.

CONCLUSION

Children with DDH exhibit varying degrees of muscle atrophy and increased fat infiltration compared to their age-matched healthy counterparts. Aside from the iliopsoas, muscle morphology and fat infiltration in DDH children improved post-treatment compared to pre-treatment levels.

[Modified gluteus maximus transfer for hip abductor deficiency]

OBJECTIVE

Transfer of the gluteus maximus with refixation at the greater trochanter for treatment of abductor deficiency.

INDICATIONS

Symptomatic abductor deficiency with atrophy and fatty degeneration of the gluteal muscles > 50% (grade 3 by quartile) with good strength of the gluteus maximus.

CONTRAINDICATIONS

Low atrophy or fatty degeneration of less than 50% of the gluteal muscles, limited strength of the gluteus maximus, infection.

SURGICAL TECHNIQUE

First, the fascia lata is incised dorsally to the tensor fascia latae muscle, with the incision extending approximately 1.5 cm proximal to the iliac crest. A second incision divides the gluteus maximus muscle longitudinally along the muscle fibers and continues towards the fascia lata distal to the greater trochanter. These incisions result in a triangular muscle flap, which is elevated and divided into anterior and posterior portions. The posterior flap is positioned ventrally over the femoral neck and fixed to the anterior capsule and the anterior edge of the greater trochanter. The anterior flap is placed directly on the proximal femur. For this purpose, a groove is prepared in the area of the proximal femur using a spherical burr to freshen up the future footprint. The anterior flap is positioned from the tip of the greater trochanter towards the insertion of the vastus lateralis muscle. Subsequently, the anterior flap is fixed to the created groove with transosseous sutures and positioned under the elevated vastus lateralis muscle in 15° abduction of the leg. To provide additional stabilization to the tendinous part of the anterior flap, a screw is inserted distally to the greater trochanter. The vastus lateralis muscle is attached to the distal tip of the anterior flap, and the remaining gluteus maximus muscle is sutured to the fascia lata to cover the anterior flap. Additionally, a flap of the tensor fascia latae muscle can be mobilized and adapted to the reconstruction. Layered wound closure is performed.

RESULTS

The technique of a gluteus maximus transfer represents a method for the treatment of chronic abductor deficiencies and improves abduction function as well as the gait pattern in short-term follow-ups. Fifteen patients (mean age at time of surgery 62 years) had after a mean follow-up of 2.5 years. The modified Harris Hip Score (mHHS) improved from 48 points preoperatively to 60 points at follow-up. Preoperatively, 100% had a positive Trendelenburg sign; at follow-up, this was about 50%.

Fatty Infiltration in Paraspinal Muscles: Predicting the Outcome of Lumbar Surgery and Postoperative Complications

Lumbar spine disorders often cause lower back pain, lower limb radiating pain, restricted movement, and neurological dysfunction, which seriously affect the quality of life of middle-aged and older people. It has been found that pathological changes in the spine often cause changes in the morphology and function of the paraspinal muscles (PSMs). Fatty infiltration (FI) in PSMs is closely associated with disc degeneration and Modic changes. And FI causes inflammatory responses that exacerbate the progression of lumbar spine disease and disrupt postoperative recovery. Magnetic resonance imaging can better distinguish between fat and muscle tissue with the threshold technique. Three-dimensional magnetic resonance imaging multi-echo imaging techniques such as water-fat separation and proton density are currently popular for studying FI. Muscle fat content obtained based on these imaging sequences has greater accuracy, visualization, acquisition speed, and utility. The proton density fat fraction calculated from these techniques has been shown to evaluate more subtle changes in PSMs. Magnetic resonance spectroscopy can accurately reflect the relationship between FI and the degeneration of PSMs by measuring intracellular and extracellular lipid values to quantify muscle fat. We have pooled and analyzed published studies and found that patients with spinal disorders often exhibit FI in PSMs. Some studies suggest an association between FI and adverse surgical outcomes, although conflicting results exist. These suggest that clinicians should consider FI when assessing surgical risks and outcomes. Future studies should focus on understanding the biological mechanisms underlying FI and its predictive value in spinal surgery, providing valuable insights for clinical decision-making.

Gluteus maximus tendon transfer as a salvage option for painful chronic hip abductor insufficiency: clinical and MRI results with a minimum follow-up of 24 months

INTRODUCTION

Chronic hip abductor insufficiency is a rare debilitating condition. In cases refractory to conservative treatment and not amenable to direct repair an augmentation becomes necessary. The preferred salvage method at our institution is augmentation with the anterior third of the gluteus maximus tendon. The aim of this study is to describe the results of 8 patients, treated for painful chronic hip abductor insufficiency with gluteus maximus muscle transfer, after a minimal follow-up of 24 months including a full clinical and MRI evaluation of the hip abductors pre- and postoperatively.

METHODS

We retrospectively reviewed a consecutive series of 8 patients who were surgically managed for painful chronic hip abductor insufficiency. All patients had a Trendelenburg sign, impaired muscle strength (M ⩽ 3) as well as a complete avulsion of the hip abductors with marked fatty degeneration (⩾3). Pain levels, muscle strength, functional scores as well as a postoperative MRI was obtained after a minimal follow-up of 24 months.

RESULTS

The mean age of the patients was 69 years, mean follow-up was 35 (26-54) months. Pain was significantly reduced postoperatively to VAS 2.5 from VAS 5 (p = 0.046). Trendelenburg sign remained positive in all patients and hip abductor strength did not improve significantly from 2.4 to 3.1 (p = 0.19). Complete healing of the transferred tendon was confirmed by MRI in all patients at last follow-up.

CONCLUSIONS

In the setting of painful chronic hip abductor insufficiency refractory to conservative treatment with advanced muscle degeneration without the possibility of a direct reconstruction the gluteus maximus tendon transfer significantly decreased pain. The effect on hip abductor strength and patient-reported functional outcome scores is limited. Despite the modest results it remains our preferred salvage treatment option for lack of better alternatives. Larger studies are necessary to confirm these findings.

Associations of Quantitative and Qualitative Muscle Parameters With Second Hip Fracture Risk in Older Women: A Prospective Cohort Study

Older women with a first hip fracture exhibit heightened susceptibility and incidence of second fracture and potentially severe consequences. This prospective study was to compare the predictive power of qualitative and quantitative muscle parameters for a second hip fracture in older women with a first hip fracture. A total of 206 subjects were recruited from the longitudinal Chinese Second Hip Fracture Evaluation study. Hip computed tomography (CT) scans were obtained immediately after the first fracture. Muscle fat infiltration was assessed according to the Goutallier classification qualitatively. Quantitative parameters included cross-sectional area and density of gluteus maximus (G.MaxM) and gluteus medius and minimus (G.Med/MinM) muscles. CT X-ray absorptiometry was used to measure the areal bone mineral density (aBMD) of the contralateral femur. Cox proportional hazards models were used to compute hazard ratios (HR) of second hip fracture risk. The mean age of subjects was 74.9 (±9.5) years at baseline. After 4.5 years, 35 had a second hip fracture, 153 without a second hip fracture, and 18 died. Except for the combined G.MinM Goutallier grade 3 and 4 groups before adjustment for covariates (HR = 5.83; 95% confidence interval [CI] 1.49-22.83), there were no significant HRs for qualitative classification to predict a second hip fracture. Among quantitative metrics, after adjustment for covariates, G.Med/MinM density was significant in the original (HR = 1.44; CI 1.02-2.04) and competing risk analyses (HR = 1.46; CI 1.02-2.07). After additional adjustment for femoral neck (FN) aBMD, G.Med/MinM density remained borderline significant for predicting a second hip fracture in competing risk analysis (HR = 1.43; CI 0.99-2.06; p = 0.057). Our study revealed that Goutallier classification was less effective than quantitative muscle metrics for predicting hip second fracture in this elderly female cohort. After adjustment for FN aBMD, G.Med/MinM density is a borderline independent predictor of second hip fracture risk. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

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.

A Cross-Sectional Study on Gluteal Muscles in Patients with Ankylosing Spondylitis at Different Stages of Hip Involvement

Hip involvement in ankylosing spondylitis (AS) is associated with severe functional impairment, and early diagnosis can improve the disease prognosis. We investigated gluteal muscle cross-sectional area (CSA) and radiodensity at different stages of hip involvement and their associations with AS-related clinical and laboratory parameters. This cross-sectional study included 83 patients with AS and 83 age- and sex-matched controls. Patients with AS were divided into three groups according to the Bath Ankylosing Spondylitis Radiology Hip Index system. The CSA and radiodensity of the gluteus maximus, medius, and minimus muscles were measured using computed tomography images. Muscle parameters were compared, and their relationships with clinical and laboratory parameters were evaluated. For the gluteus maximus, patients with AS had a lower CSA than controls, regardless of the degree of hip involvement. For the gluteus medius and minimus, patients with moderate/advanced hip involvement had significantly lower CSA and radiodensity than those with mild to no hip involvement. The severity of hip involvement was negatively associated with muscle parameters. CSA of the gluteus maximus decreased in early-stage hip involvement without any changes in radiographs, while radiodensity decreased in the later stages. Muscle parameters on computed tomography may be a more sensitive indicator than radiographic findings.

Gluteal muscle fatty infiltration, fall risk, and mobility limitation in older women with urinary incontinence: a pilot study

OBJECTIVE

Gluteal muscle quality influences risk of falling and mobility limitation. We sought (1) to compare gluteal muscle fatty infiltration (FI) between groups of older women with urinary incontinence (UI) at risk for falling (at-risk group) and not at risk for falling (not-at-risk group), and (2) to determine correlation of gluteal FI with Timed Up and Go (TUG) and Short Physical Performance Battery (SPPB) performance.

MATERIALS AND METHODS

Prospective pilot study of gluteal FI on pelvis MRI for 19 women with UI, aged ≥ 70 years. A musculoskeletal radiologist selected axial T1-weighted MR images; then, two blinded medical student research assistants analyzed gluteal FI by quantitative fuzzy C-means segmentation. TUG and SPPB tests were performed. TUG ≥ 12 s defined participants as at risk for falling. Descriptive, correlation, and reliability analyses were performed.

RESULTS

Mean age, 76.3 ± 4.8 years; no difference for age or body mass index (BMI) between the at-risk (n = 5) versus not-at-risk (n = 14) groups. SPPB score (p = 0.013) was lower for the at-risk group (6.4 ± 3.1) than for the not-at-risk group (10.2 ± 1.9). Fuzzy C-means FI-%-estimate differed between the at-risk group and the not-at-risk group for bilateral gluteus medius/minimus (33.2% ± 15.6% versus 19.5% ± 4.1%, p = 0.037) and bilateral gluteus maximus (33.6% ± 15.6% versus 19.7% ± 6.9%, p = 0.047). Fuzzy C-means FI-%-estimate for bilateral gluteus maximus had significant (p < 0.050) moderate correlation with age (rho =  - 0.64), BMI (rho = 0.65), and TUG performance (rho = 0.52). Fuzzy C-means FI-%-estimates showed excellent inter-observer and intra-observer reliability (intraclass correlation coefficient, ≥ 0.892).

CONCLUSION

Older women with UI at risk for falling have greater levels of gluteal FI and mobility limitation as compared to those not at risk for falling.

Abductor muscle function after anterolateral approach in patients with unilateral end-stage hip osteoarthritis undergoing total hip arthroplasty: A prospective study

Background

Total hip arthroplasty (THA) is a successful procedure for treating end-stage hip osteoarthritis (OA). Regarding the surgical approach for THA, the anterolateral (AL) approach, which requires anterior hemimyotomy of the gluteus medius muscle, has shown a long-term favorable outcome. However, to date, complete information related to hip abductor muscle outcomes after the AL approach is unavailable. This study therefore aimed to evaluate the postoperative outcome of patients who undergo THA using the AL approach in terms of hip abductor muscle recovery, pain, function, and muscle healing status.

Methods

Twenty patients diagnosed with unilateral end-stage hip OA underwent cementless THA with the AL approach. All patient procedures were performed by a single surgeon. Preoperative and postoperative data were collected at 2-week, 6-week, 3-month, and 6-month follow-up periods. Hip abductor muscle power was measured via handheld dynamometer. The healing of the musculotendinous repair was evaluated with magnetic resonance imaging at 9 months.

Results

After THA, hip abductor muscle power in the operated hip significantly increased as early as 3 months post-procedure when compared with the preoperative value (p < 0.05). The other parameters-including pain score, Harris hip score, and WOMAC score-significantly improved as early as 2 weeks post-operation (p < 0.05). In all patients, MRI scans showed good healing of the muscle repair site without a gap in the gluteus medius muscle. However, three patients (15%) had some fibrosis and tendon swelling at the repair site.

Conclusion

This study demonstrated that patients with end-stage hip OA could experience significantly improved hip abductor motor function as early as 3 months after undergoing THA with the AL approach. Moreover, despite patients experiencing anterior hemimyotomy of the gluteus medius muscle, no significant complications emerged at the muscle repair site in the AL approach.

Plantar Plating in the Modified Lapidus Procedure: Evaluation of Function and Impairment of the Tibialis Anterior Tendon

The modified "Lapidus" procedure (MLP) describes the arthrodesis of the first tarsometatarsal joint. We investigate if there are detectable changes of the tendon or the function of the muscle and clinical outcome after MLP. We reviewed 22 feet. All patients underwent magnetic resonance imaging (MRI) at an average of 27 (range, 12-49) months. Clinical outcome was evaluated using the European Foot and Ankle Society score. Strength was measured and complications were assessed. MRI revealed signs of tendinopathy of the tibialis anterior tendon in 13 feet (59%). The mean total European Foot and Ankle Society score at final follow-up was 17 (range, 6-24) points. The mean postoperative Visual Analog Scale score was 1.4 (range, 0-5). Range of motion and force data were not significantly different to the contralateral side. In conclusion, MRI showed signs of tendinopathy in 59%, which does not seem to affect clinical outcome, but has to be considered when choosing the desired implant and placement. MLP leads to high patient satisfaction rates and significant improvement at midterm follow up.

MRI assessment of minimally invasive anterolateral approaches in total hip arthroplasty

INTRODUCTION

Total hip arthroplasty (THA) on a minimally invasive anterolateral (MIAL) approach frequently leads to gluteus minimus and gluteus medius lesions, and sometimes to tensor fasciae latae (TFL) denervation. We therefore developed compensatory strategies, which we assessed on pre- and post-operative MRI: 1) to assess gluteus minimus and gluteus medius fatty infiltration (FI), 2) to assess TFL FI, and 3) to assess FI in the other periarticular muscles.

HYPOTHESIS

The modified MIAL approach reduces the rate of gluteus minimus and gluteus medius lesion.

MATERIALS AND METHODS

A continuous prospective single-surgeon series of THA using a MIAL approach included 25 patients. Femoral implantation was performed with the hip in extension so as to distance the proximal femur from the gluteals, avoiding muscle trauma. The superior gluteal nerve branch in the space between the gluteus medius and TFL, running toward the TFL, was systematically released and protected. MRI was performed preoperatively and at 3 months and 1 year post-surgery. FI was analyzed according to the Goutallier classification in all periarticular muscles.

RESULTS

One patient lacked preoperative MRI and was excluded, leaving 24 patients, for 72 MRIs. In 10/24 patients (41.7%) the gluteus minimus and in 8/24 patients (33.3%) the anterior third of the gluteus medius showed ≥2 grade increase in FI between preoperative and 1-year MRI, with significant increases in both at 3 months (p<0.001) and 1 year (p<0.001). At least a 2 grade increase in FI at 1 year was seen in 1 patient (4.2%) in the TFL, in 2 (8.3%) in the piriformis, and in 1 (4.2%) in the obturator internus. There were no significant differences in FI between preoperative, 3-month or 1-year MRI in any other periarticular muscles.

CONCLUSION

Femoral implantation in hip extension did not reduce the rate of gluteal lesions, which remained frequent. In contrast, release of the superior gluteal nerve branch could be effective in conserving TFL innervation. Some rare lesions of the proximal part of the pelvi-trochanteric muscles were also observed.

LEVEL OF EVIDENCE

IV, Prospective case series.

Comparative MRI assessment of three minimally invasive approaches in total hip arthroplasty

INTRODUCTION

Minimally invasive approaches (direct anterior approach: DAA; minimally invasive anterolateral: MIAL; piriformis-sparing posterior approach: PSPA) are widely used for total hip arthroplasty (THA), with a muscle-sparing objective. There are no published comparative studies of muscle damage secondary to these approaches. The aim of the present study was to compare fatty infiltration (FI) on MRI induced by DAA, MIAL and PSPA in THA 1) in the tensor fasciae latae (TFL) and sartorius muscles, 2) in the gluteal muscles, and 3) in the pelvitrochanteric muscles.

HYPOTHESIS

Greater FI is induced by DAA in anterior muscles, by MIAL in gluteal muscles and by PSPA in pelvitrochanteric muscles.

MATERIALS AND METHODS

Three continuous prospective series of THA by DAA, MIAL and PSPA included 25 patients each. MRI was performed preoperatively and at 1 year postoperatively. FI was graded on the Goutallier classification in all periarticular hip muscles. Muscles showing ≥2 grade aggravation at 1 year were considered damaged.

RESULTS

Nine patients whose preoperative MRI was uninterpretable were excluded. In all, 66 patients (21 DAA, 24 MIAL and 21 PSPA) with 132 MRI scans were analyzed. TFL was damaged in 2/21 DAA patients (9.5%), 1/24 MIAL patients (4.2%) and 0/21 PSPA patients (0%). There were no sartorius lesions. The anterior third of the gluteus medius was damaged in 8/24 MIAL patients (33.3%) and the gluteus minimus in 10/24 (41.7%), compared to 1/21 DAA patients (4.8%) and 0/21 PSPA patients (0%). The mid and posterior thirds of the gluteus medius and the gluteus maximus were never damaged. The piriformis muscle was damaged in 3/21 DAA patients (14.3%), 2/24 MIAL patients (8.3%) and 2/21 PSPA patients (9.5%). The obturator internus was damaged in 4/21 DAA patients (19%), 1/24 MIAL patients (4.2%) and 16/21 PSPA patients (76.2%). The obturator externus and quadratus femoris were mainly damaged in PSPA patients: respectively, 5/21 (23.8%) and 4/21 patients (19%)).

CONCLUSION

The muscle-sparing properties of minimally invasive hip approaches are only theoretical. In the present series, there were rare TFL lesions with DAA and MIAL. Gluteus medius and minimus lesions were frequent in MIAL. Pelvitrochanteric muscles lesions were more frequent in PSPA, but found in all 3 approaches. These findings should help guide surgeons in their choice of approach and in informing patients about the damage these minimally invasive approaches can cause.

LEVEL OF EVIDENCE

III, prospective comparative study.

Impact of fatty degeneration on the functional outcomes of 38 patients undergoing surgical repair of gluteal tendon tears

BACKGROUND

Gluteal tendon tears (GTT) can cause pain and weakness of the hip. We analyze the impact of gluteal muscle fatty degeneration, atrophy and tear morphology on clinical outcomes of surgical repair.

METHODS

All sequential patients receiving surgical repair of GTTs via anchor sutures between 1/2015 and 11/2018 were retrospectively identified. MRIs were reviewed by a radiologist for tendon retraction, muscle atrophy and tear size. The Goutallier-Fuchs Classification (GFC) was used to quantify fatty degeneration as < 2° or ≥ 2°. Demographic and clinical variables were abstracted from the electronic records. The surveys HHS Section 1 and HOOS Jr. were obtained at last follow-up. The Pearson correlation and one-way ANOVA tests served for statistical analysis of clinical variance.

RESULTS

38 patients were identified, 29 (76.3%) were female. The average age was 67. Of the 11 (28.9%) patients with a prior hip arthroplasty 87.5% of primary THAs had a direct lateral approach. 29 (76.3%) patients were treated open and 9 (23.7%) arthroscopically. At an average follow-up of 20.9 months, patients reported a significant improvement in pain (97%), analgesic use (85.7%), limp (52.6%) and abduction strength (54.2%) (all: P ≤ 0.01). GFC ≥ 2° were associated with significantly worse outcomes in terms of limp (0.19/3 vs. 1.2/3, P = 0.05), HHS-S1 (58.19 vs. 71.68, P = 0.04) and complication rates (37.5% vs. 0%, P = 0.02). There was a strong correlation between tear retraction (P = 0.005), tear size (P = 0.009) and muscle atrophy (P = 0.001) with GFC ≥ 2° but not with clinical outcomes. GFC ≥ 2° was strongly related to lateral THA exposures (P < 0.001). Surgical approach had no impact on clinical outcomes.

CONCLUSION

While fatty degeneration can negatively impact functional outcomes, pain relief is reliably achieved. Tear morphology and muscle atrophy did not correlate with outcomes in this patient cohort. Patients should be counseled to expect a residual limp after surgery if they have GFC ≥ 2° on MRI.

No Difference in Hip Muscle Volumes and Fatty Infiltration in Those With Hip-Related Pain Compared to Controls

Background

Little is known about muscle morphology in people with hip-related pain, without signs of femoro-acetabular impingement syndrome (FAIS). Identifying changes in hip muscle volume, fatty infiltrate and establishing relationships between muscle volume and strength, may provide insight into potential early treatment strategies.

Purposes

To: (i) compare the volumes and fatty infiltrate of gluteus maximus, gluteus medius, gluteus minimis, tensor fascia latae and quadratus femoris between symptomatic and less-symptomatic sides of participants with hip-related pain; (ii) compare the volumes and fatty infiltrate of hip muscles between healthy controls and symptomatic participants; and (iii) explore relationships of hip muscle volumes to muscle strength and patient-reported outcome measures in people with hip-related pain.

Study Design

Cross-sectional study.

Methods

Muscle volume and fatty infiltrate (from magnetic resonance imaging), hip muscle strength, patient-reported symptoms, function and quality of life (QOL) were determined for 16 participants with hip-related pain (no clinical signs of FAIS; 37±9 years) and 15 controls (31±9 years). Using One Way Analysis of Co-Variance tests, muscle volume and fatty infiltrate was compared between the symptomatic and less-symptomatic sides in participants with hip-related pain as well as between healthy controls and symptomatic participants. In addition, hip muscle volume was correlated with hip muscle strength, hip-reported symptoms, function and QOL.

Results

No differences in all the studied muscle volumes or fatty infiltrate were identified between the symptomatic and less-symptomatic hips of people with hip-related pain; or between people with and without hip-related pain. Greater GMED volume on the symptomatic side was associated with less symptoms and better function and QOL (ρ=0.522-0.617) for those with hip-related pain. Larger GMAX volume was associated with greater hip abduction and internal rotation strength, larger GMED volume was associated with greater hip extension strength, and larger QF volume was associated with greater hip abduction strength (rho=0.507-0.638).

Conclusion

People with hip-related pain and no clinical signs of FAIS have hip muscle volumes that are not significantly different than those of matched pain-free controls or their less-symptomatic hip. Larger GMED muscle volume was associated with fewer symptoms and greater strength.

Level of evidence

Level 3a.

Repair of gluteus medius tears with bioinductive collagen patch augmentation: initial evaluation of safety and imaging

The purpose of this study was to perform an initial, prospective evaluation of imaging findings and outcomes after open surgical repair of gluteus medius tendon tears with bioinductive collagen patch augmentation. A prospective study was performed of patients with clinical and magnetic resonance imaging (MRI) evidence of symptomatic gluteus medius tears who underwent open, double-row suture anchor repair with bioinductive bovine collagen patch augmentation. Preoperative and 6-month postoperative MRIs were reviewed by a fellowship-trained musculoskeletal radiologist, and outcome scores were recorded preoperatively and 6 months postoperatively [Hip Outcome Score (HOS) Sport; HOS Activities of Daily Living (HOS ADL); Modified Harris Hip Score (mHHS) and International Hip Outcomes Tool (iHOT-33)]. Nine patients, four high-grade tears (≥50% tendon thickness) and five low-grade tears (<50% thickness) underwent surgical repair. At 6 months, 7/9 (77.8%) of tendons were qualitatively classified as completely healed on MRI, with no complications. Mean tendon thickness increased significantly: mediolateral dimension by 5.8 mm (P < 0.001), anteroposterior dimension by 4.1 mm (P = 0.02) and cross-sectional area (CSA) by 48.4 mm² (P = 0.001). Gluteus medius and minimus CSA did not change significantly (P > 0.05). Patients demonstrated improvements in mean scores for HOS ADL, mHHS and iHOT that met defined minimum clinically important differences (P < 0.05). Open surgical repair of gluteus medius tendon tears with bioinductive collagen patch augmentation is safe and associated with increased tendon thickness on postoperative MRI. Early outcome scores are encouraging and should be evaluated after patients have completed postoperative rehabilitation to measure the whole effect of treatment.

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.

Towards defining muscular regions of interest from axial magnetic resonance imaging with anatomical cross-reference: a scoping review of lateral hip musculature

BACKGROUND

Measures of hip muscle morphology and composition (e.g., muscle size and fatty infiltration) are possible with magnetic resonance imaging (MRI). Standardised protocols or guidelines do not exist for evaluation of hip muscle characteristics, hindering reliable and valid inter-study analysis. This scoping review aimed to collate and synthesise MRI methods for measuring lateral hip muscle size and fatty infiltration to inform the future development of standardised protocols.

METHODS

Five electronic databases (Medline, CINAHL, Embase, SportsDISCUS and AMED) were searched. Healthy or musculoskeletal pain populations that used MRI to assess lateral hip muscle size and fatty infiltration were included. Lateral hip muscles of interest included tensor fascia late (TFL), gluteus maximus, gluteus medius, and gluteus minimus. Data on MRI parameters, axial slice location, muscle size and fatty infiltrate measures were collected and analysed. Cross referencing for anatomical locations were made between MRI axial slice and E-12 anatomical plastinate sections.

RESULTS

From 2684 identified publications, 78 studies contributed data on volume (n = 31), cross sectional area (CSA) (n = 24), and fatty infiltration (n = 40). Heterogeneity was observed for MRI parameters and anatomical boundaries scrutinizing hip muscle size and fatty infiltration. Seven single level axial slices were identified that provided consistent CSA measurement, including three for both gluteus maximus and TFL, and four for both gluteus medius and minimus. For assessment of fatty infiltration, six axial slice locations were identified including two for TFL, and four for each of the gluteal muscles.

CONCLUSIONS

Several consistent anatomical levels were identified for single axial MR slice to facilitate muscle size and fatty infiltration muscle measures at the hip, providing the basis for reliable and accurate data synthesis and improvements in the validity of future between studies analyses. This work establishes the platform for standardised methods for the MRI assessment of lateral hip musculature and will aid in the examination of musculoskeletal conditions around the hip joint. Further studies into whole muscle measures are required to further optimise methodological parameters for hip muscle assessment.

The Intergluteal Fat Stripe in Patients With Hip Abductor Tears

Background:

With a hip abductor tendon tear, widening of the intergluteal space, or “fat stripe,” is a characteristic change seen in and around the gluteus medius and minimus.

Purpose:

To determine the relationship of the intergluteal fat stripe in hips with pathologic abductor tears compared with the contralateral side and to evaluate the association of fat stripe size with hip-specific patient-reported outcome measures.

Study Design:

Case series; Level of evidence, 4.

Methods:

Of the 43 patients (42 female, 1 male; mean age, 56.6 years; range, 38-85 years) who underwent endoscopic gluteus medius repair, 19 met inclusion criteria of preoperative bilateral hip magnetic resonance imaging (MRI) scans and 2-year follow up. A single board-certified fellowship-trained orthopaedic surgeon (J.F.), who was blinded to outcomes, evaluated the MRI scans to measure the intergluteal fat stripe on the operative and nonoperative sides. The 2-year postoperative International Hip Outcome Tool (iHOT-12) and modified Harris Hip Score (mHHS) values were analyzed to determine their relationship to the size of the fat stripe. Statistical analysis was performed using a paired t test, and associations were determined using Pearson product correlation as well as nonparametric measurements.

Results:

The size of the intergluteal fat stripe differed significantly between the operative and nonoperative sides. The area of the fat stripe on the operative side was 645.73 ± 513.09 mm2, and on the nonoperative side it was 313.47 ± 360.71 mm2, an average of 332.36 mm2 greater than the nonoperative side ( P = .02). The width of the fat stripe was 9.10 ± 4.60 mm on the operative side and 5.15 ± 3.87 mm on the nonoperative side, 3.95 mm greater than the nonoperative side ( P < .01). There was no correlation between the width or area of the fat stripe on the operative side and iHOT-12 or mHHS values at 2-year follow-up.

Conclusion:

The study findings indicated that the intergluteal fat stripe is significantly wider and has a significantly larger area in hips with abductor tears compared with unaffected hips. This did not correlate with 2-year patient-reported outcomes.

Obesity could be associated with poor paraspinal muscle quality at upper lumbar levels and degenerated spine at lower lumbar levels: Is this a domino effect?

Vertebral end-plate changes and paraspinal muscles are recently getting much more attention, since they could be associated with intervertebral disc degeneration (IVDD) and low back pain (LBP). Even though obesity is known as a risk factor for LBP, the role of obesity in the process of LBP is still controversial. In this study, we aimed to identify whether increased body mass index (BMI) was associated with IVDD, vertebral end-plate changes and paraspinal muscle quality. Consecutive women and men, aged between 20 and 50 years, presented with chronic LBP to the outpatient clinics were included. Patients were evaluated in terms of IVDD, vertebral end-plate changes, fatty infiltration in the paraspinal muscles at all lumbar levels on magnetic resonance imaging. Severe IVDD was more common in obese patients than in non-obese patients (73.5% vs. 50.4%, p = 0.017). When we compared the groups level by level, the significant difference for severe IVDD was present only at L4-L5 disc level (50% vs. 27.4%, p = 0.013). There was a higher trend of harboring Modic change at any lumbar level in obese patients, significantly in women (35.9% vs. 16.4%, p = 0.026). More severe fatty infiltration in the paraspinal muscles was seen at upper lumbar levels of the obese patients, particularly in women. Patients with higher BMI and suffering from LBP, had more fatty infiltration in the paraspinal muscles at the upper lumbar levels, more severe IVDD, and Modic changes at the lower lumbar levels; particularly women.

RELIABILITY OF THE GOUTALLIER CLASSIFICATION SYSTEM IN THE EVALUATION OF THE MULTIFIDUS MUSCLE

ABSTRACT Introduction: The paravertebral musculature is essential for the biomechanics and stability of the spine, and its involvement in the pathophysiology of spinal diseases has been demonstrated. Qualitative evaluation of muscle degeneration is usually performed by analyzing the fat infiltration rate proposed by the Goutallier classification system. Objective: The objective of this study is to analyze the intra- and interobserver agreement of the Goutallier Classification for the evaluation of fatty degeneration of the multifidus muscle, using magnetic resonance imaging exams. Methods: The study included 68 patients, all diagnosed with symptomatic disc hernia and indicated for surgery. Preoperative magnetic resonance images were used for the analyses. The images were initially evaluated by two orthopedists and two medical students, and then re-evaluated after two weeks. Intra- and inter-observer reliability analysis was performed using the Fleiss Kappa test and the Landis and Koch criteria. All the analyses were performed using the R statistical environment (R Development Core Team, version 3.3.1, 2016) and the significance level was set at 5%. Results: The percentages of intra- and inter-observer agreement were 86.76% and 61.03%, respectively. The intraobserver agreement was near perfect and the interobserver agreement was moderate. Conclusion: The Goutallier Classification System showed moderate interobserver and intraobserver agreement, being a relevant tool for the evaluation of paravertebral musculature fat replacement. Level of evidence II; Prospective study for diagnostic purposes.

MRI assessment of piriformis-sparing posterior approach in total hip arthroplasty

INTRODUCTION

In total hip arthroplasty (THA), the posterior approach is the most common throughout the world. Dislocation is one of the main complications incurred, but the risk may be reduced by sparing posterior structures. Thus, piriformis-sparing posterior approaches (PSPA) were described, and satisfactory conservation of the muscle was reported. On the other hand, a recent cadaver study reported occult intrapelvic piriformis lesions in 91% of cases. In the light of this discordance, we performed pre- and postoperative MRI in THA by PSPA: 1) to assess the fatty infiltration of the piriformis induced by the approach, with particular attention to intrapelvic lesions; and 2) to assess fatty infiltration of the other periarticular muscles.

HYPOTHESIS

The piriformis muscle will show little fatty infiltration following PSPA.

MATERIALS AND METHODS

A continuous prospective single-surgeon series of THA by PSPA included 25 patients. MRI was performed preoperatively and at 3 months and 1 year postoperatively. Fatty infiltration was assessed on the Goutallier classification in all periarticular muscles.

RESULTS

Preoperative MRI was lacking in 4 patients, who were excluded from analysis; 21 patients with MRI were thus analyzed. In the piriformis muscle, there was no significant change in fatty infiltration between preoperative and 3-month (p=0.29) or 1-year (p=0.41) MRI. Two of the 21 patients (9.5%) showed grade 3 or 4 fatty infiltration at 1 year, compared to 0/21 (0%) preoperatively; both showed sacral avulsion of the piriformis. Significant differences between preoperative and 1-year MRI were found for the obturator internus and externus, with grade 3 or 4 infiltration at 1 year in 14 cases for the obturator internus (14/21: 66.7%), in 3/21 for the obturator externus (14.3%) and in 6/21 for the quadratus femoris (28.6%), compared to respectively 0/21 (0%), 0/21 (0%) and 3/21 (14.3%) preoperatively. There were no significant differences for any of the other periarticular muscles.

CONCLUSION

PSPA in THA ensured good conservation of the piriformis. There may, however, be rare and irreversible sacral lesions invisible intraoperatively.

LEVEL OF EVIDENCE

IV; prospective case series.

Assessing Fatty Infiltration of Paraspinal Muscles in Patients With Lumbar Spinal Stenosis: Goutallier Classification and Quantitative MRI Measurements

Objective: Fatty infiltration of paraspinal muscle is associated with spinal disorders. It can be assessed qualitatively (i.e., Goutallier classification) and quantitatively using image processing software. The aims of this study were to compare paraspinal muscle fatty infiltration as assessed using the Goutallier classification vs. quantitative magnetic resonance images (MRI) measurements and to investigate the association between anthropometric parameters and paraspinal muscle morphology and fatty infiltration in patients with symptomatic lumbar spinal stenosis (LSS).

Methods: Patients affected by symptomatic LSS scheduled for surgery with available MRI of the lumbar spine were included in this retrospective cross-sectional study. Fatty infiltration at each lumbar level was rated qualitatively according to the Goutallier classification and quantified based on the cross-sectional area (CSA) of the paraspinal muscle, of its lean fraction (LeanCSA), and the ratio between LeanCSA and CSA and the CSA relative to the CSA of vertebral body (RCSA). Considering the muscle as a single unit, overall fatty infiltration according to Goutallier, overall CSA, LeanCSA, LeanCSA/CSA, and RCSA were computed as averages (aGoutallier, aCSA, aLeanCSA, aLeanCSA/aCSA, and aRCSA). Associations among parameters were assessed using Spearman's respective Pearson's correlation coefficients.

Results: Eighteen patients, with a mean age of 71.3 years, were included. aGoutallier correlated strongly with aLeanCSA and aLeanCSA/aCSA (R = −0.673 and R = −0.754, both P < 0.001). There was a very strong correlation between values of the left and right sides for CSA (R = 0.956, P < 0.001), LeanCSA (R = 0.900, P < 0.001), and LeanCSA/CSA (R = 0.827, P < 0.001) at all levels. Among all anthropometric measurements, paraspinal muscle CSA correlated the most with height (left: R = 0.737, P < 0.001; right: R = 0.700, P < 0.001), while there was a moderate correlation between vertebral body CSA and paraspinal muscle CSA (left: R = 0.448, P < 0.001; right: R = 0.454, P < 0.001). Paraspinal muscle CSA correlated moderately with body mass index (BMI; left: R = 0.423, P < 0.001; right: R = 0.436, P < 0.001), and there was no significant correlation between aLeanCSA or aLeanCSA/CSA and BMI.

Conclusions: The Goutallier classification is a reliable yet efficient tool for assessing fatty infiltration of paraspinal muscles in patients with symptomatic LSS. We suggest taking body height as a reference for normalization in future studies assessing paraspinal muscle atrophy and fatty infiltration.

[Avulsion injuries of the gluteus medius and gluteus minimus muscles]

Avulsion injuries of the gluteus medius and gluteus minimus muscles represent a diagnostic and therapeutic challenge. Such injuries are rarely to be expected in high-energy trauma. Degenerative damage or iatrogenic injuries in the context of hip surgery are more frequently identified as the cause. Clinically, in addition to lateral hip pain, limping is an important finding and depends on the extent of the tendon damage. In addition to the medical history and clinical examination, imaging by means of sonography and, above all, magnetic resonance imaging (MRI, possibly with artifact-reduced sequences in the presence of an endoprosthesis) are diagnostically groundbreaking. Therapeutically, a stepwise approach is indicated according to the extent of rupture and quality of the gluteal tendon and muscle tissues. Specific conservative training regimens, mini-open/endoscopic anatomic reconstruction techniques in cases of gluteal muscle integrity and muscle transfer techniques as salvage option with chronic mass ruptures are available. The common goal is the restoration of everyday occupational and private activities to regain the quality of life.

Reliability of a Novel Scoring System for MRI Assessment of Severity in Gluteal Tendinopathy: The Melbourne Hip MRI Score

Background

Gluteal tendinopathy is commonly reported in the literature, but there is a need for a validated magnetic resonance imaging (MRI)-based scoring system to grade the severity of the tendinopathy.

Purpose

To use intra- and interobserver reliability to validate a new scoring system, the Melbourne Hip MRI (MHIP) score, for assessing the severity of gluteal tendinopathy.

Study Design

Cohort study (diagnosis); Level of evidence, 3.

Methods

The MHIP score assesses gluteal tendinopathy according to each 1 of 5 categories: (1) extent of tendon pathology (maximum 5 points); (2) muscle atrophy (maximum 4 points); (3) trochanteric bursitis (maximum 4 points); (4) cortical irregularity (maximum 3 points); and (5) bone marrow edema (maximum 1 point), with an overall range of 0 to 17 (most severe). A total of 41 deidentified MRI scans from 40 patients diagnosed with gluteal tendinopathy (mean baseline age, 57.44 ± 25.26 years; 4 male, 36 female) were read and graded according to MHIP criteria by 2 experienced musculoskeletal radiologists. The radiologists were blinded to previous reports, and the scans were read twice within a 2-month period. Statistical analysis using the intraclass correlation coefficient (ICC) was used to determine intra- and interobserver reliability and mean/range for the MHIP scores.

Results

Of a total of 123 readings, the mean MHIP score (±SD) was 3.93 ± 2.24 (range, 0-17 points). The MHIP score demonstrated excellent reliability for determining the severity of gluteal tendinopathy on MRI. The ICC for intra- and interobserver reliability was 0.81 (95% CI, 0.67-0.89) and 0.78 (95% CI, 0.62-0.87), respectively.

Conclusion

The MHIP score had excellent intra- and interobserver reliability in scoring gluteal tendinopathy. This score allows gluteal tendon pathology to be graded prior to treatment and to be used for standardized comparisons between results in future research undertaking radiological review of gluteal tendinopathy.

MARS MRI assessment of fatty degeneration of the gluteal muscles in patients with THA: reliability and accuracy of commonly used classification systems

INTRODUCTION

Fatty degeneration of the gluteal muscles on metal artefact reduction sequence (MARS) MRI has been shown to correlate with poor functional outcomes, particularly in patients with total hip arthroplasty (THA). Standardized, reliable classification systems that permit assessment of fatty gluteal infiltration are needed for clinical decision making. This study aimed to compare the reproducibility and accuracy of commonly used MRI classification systems for fatty gluteal atrophy in THA patients.

METHODS

MARS magnetic resonance images of 82 patients with unilateral THA were analysed by three independent trained observers. The readers evaluated fatty degeneration of the gluteus minimus, gluteus medius, and gluteus maximus according to 3 widely used classification systems: Goutallier, Quartile, and Bal and Lowe. Interobserver and intraobserver repeatability were determined using the weighted Kappa test. Quantitative evaluation of the proportion of intramuscular fat based on MR signal intensities was obtained and represented the gold standard.

RESULTS

Mean interobserver agreement for the Quartile classification system (0.93) was higher compared with Goutallier classification system (0.87) and the Bal and Lowe classification system (0.83; range 0.79-0.88; p = 0.04). Intraobserver repeatability was significantly higher for the Quartile classification system (weighted kappa 0.91, 0.89, 0.85) compared with the Bal and Lowe classification system (weighted kappa 0.83, 0.77, 0.75; p < 0.01) and Goutallier classification system (weighted kappa 0.83, 0.77, 0.75; p = 0.04). Agreement with the gold standard measurements was significantly higher in the Quartile classification system (0.88, 0.84, 0.81) compared with the Goutallier classification system (0.80, 0.77, 0.78; p = 0.02) and Bal and Lowe classification system (0.76, 0.74, 0.73; p < 0.01).

DISCUSSION

This study directly compared three clinically used MRI classification systems for fatty gluteal muscle atrophy in THA patients. Our findings demonstrate that although all three classification systems demonstrate good reproducibility and accuracy, the Quartile classification system is superior to the others in terms of intraobserver reliability and accuracy to quantify fatty gluteal degeneration in THA patients.

Techniques and outcomes of hip abductor reconstruction following tumor resection in adults

The function of the abductor mechanism (AM) of the hip can be disturbed, or even compromised, following tumor resection in the hip area. The consequences are instability (limping, dislocation), pain and altered walking ability. Several reconstruction techniques can be used for the same AM sacrifice. After defining the AM, this lecture will discuss the best technique for a given type of bone and muscle resection. These reconstruction techniques depend on exactly where the AM was sacrificed. For zone 1 resections of the ilium and/or iliac gluteal insertions, reconstruction is often optional. When muscle from the AM is resected, especially when the gluteal tendon is detached from its trochanteric insertion, isolated reconstruction can be done or reconstruction in combination with a tendon allograft or an allograft and/or tendon transfer from the surrounding area. This sacrifice, whether followed by reconstruction or not, in most cases leads to a good functional outcome, except when a complete musculotendinous unit or the superior gluteal nerve is sacrificed. Isolated resection of the greater trochanter is rare; however, this completely disrupts the continuity of the AM and justifies reconstruction, often using a bone-tendon allograft. Proximal femur resection is the most common scenario. The extent of the trochanteric resection and the gluteal tendon attachments drives the type of prosthesis used. The two most used techniques consist in an allograft sleeve over a long cemented femoral stem (allograft prosthesis composite - APC) or a modular proximal femoral endoprosthesis (megaprosthesis) with a specific AM fixation system (small plate or wire cerclage, resorbable or metal wire, synthetic reattachment tube). These two techniques yield nearly identical long-term functional outcomes with complications specific to each: osteolysis and fracture for APC, failure of tendon reattachment for megaprosthesis. Beyond these technical considerations, one must consider the poor availability of massive bone allografts. This is a highly relevant issue in France, and partially explains the shift to reconstruction with a megaprosthesis. Lastly, we will look at the different clinical and diagnostic tests used to evaluate the function of the AM in an oncology context and the outcomes of the various types of reconstruction.

Abductor muscle strengthening in THA patients operated with minimally-invasive anterolateral approach for developmental hip dysplasia

OBJECTIVE

In developmental hip dysplasia (DDH) patients, the chronic dislocation of the femoral head with respect to the true acetabulum determines muscle contracture and atrophy, particularly of the abductor muscles, and leads to secondary osteoarthritis (OA) with severe motor dysfunction, pain and disability. The correct positioning when a total hip replacement (THR) is performed is fundamental to the recovery of gait function. Also, inadequate rehabilitation of the abductor muscles for pelvic stabilisation can be responsible for residual dysfunction. Consensus on a programme for abductor muscle strengthening in these patients is not currently available. The aim of this study was to evaluate the effectiveness of a specific program of exercises for strengthening the abductor muscles in these patients.

METHODS

A multicentre, prospective, randomised clinical trial was carried out in an outpatient rehabilitation setting on 103 patients given THR for DDH through a minimally-invasive anterolateral approach. Patients were randomly divided into a Study Group, including 46 patients, and a Control Group, including 57 patients. All patients underwent standard early postoperative rehabilitation. In addition, the Study Group were given an extra 2-week rehabilitation once full weight-bearing on the operated limb was allowed, aimed at strengthening the abductor muscles. All patients were evaluated preoperatively, and at about 3 and 6 months postoperatively. Clinical measures (lower limb-length differences, hip range of motion, abductor muscle strength), and functional measures (WOMAC, HHS, 10mt WT, SF-12) were taken.

RESULTS

Hip range of motion and functional outcome measures showed a progressive improvement at follow ups in both groups, significantly higher in the Study Group. In particular, abductor strength at 6 months post-op improved by 92.5% with respect to 35.7% in the Control Group.

CONCLUSION

In addition to standard rehabilitation, a rehabilitation programme for strengthening the gluteal muscles in DDH patients who underwent THR determined an increase in muscle strength that improved functional performance and patient satisfaction.

Fatty muscle infiltration of the hip lateral rotator muscles following direct anterior minimally invasive total hip arthroplasty

INTRODUCTION

There is no consensus as to the best surgical approach to use when doing total hip arthroplasty (THA). There has been renewed interest in recent years in so-called anatomic minimally invasive direct anterior approaches (DAA). However, their reduced impact has not been confirmed with imaging data. This led us to carry out a prospective study to 1) evaluate fatty infiltration (FI) of muscles around the hip joint and 2) analyze how this FI changes over time.

HYPOTHESIS

THA done by the DAA induces FI of the anterolateral muscles around the hip adjacent to the approach.

MATERIAL AND METHODS

A continuous case series of THA by DAA using a traction table was done by a single experienced surgeon. MRI images (GE Optima* MR360 1.5T) were taken preoperatively, then at 3 months and 1 year after the THA surgery. Muscle FI was classified as described by Goutallier by an independent radiologist on all the muscles around the hip joint. A Wilcoxon test was used to compare the preoperative MRI data to the data at 3 months and 1 year postoperative.

RESULTS

Sixty-nine MRI examinations were done in 23 patients. Two were not interpretable because the patient moved during the preoperative acquisition. No intraoperative or postoperative complications were reported. None of the patients had hip pain or limped at 1 year postoperative. The FI was significantly worse from the preoperative MRI to the 3-month postoperative MRI (p=0.02) and 1-year MRI (p=0.0007) in the internal obturator muscle and at 1 year in the piriformis muscle (p=0.04). There was no significant difference for the other muscles. The rectus femoris, superior and inferior gemellus muscles and the quadratus femoris could not be analyzed.

DISCUSSION

Our hypothesis was not confirmed, although we had a paradoxical finding of muscle FI in the posterior lateral rotator muscles not the anterolateral muscles after THA by DAA. These lesions may be secondary to detachment or denervation of these muscles when elevating the femur to prepare the femoral canal or insert the stem.

LEVEL OF EVIDENCE

IV; Prospective case series.

Hip abductor tears in ischiofemoral impingement

PURPOSE

Ischiofemoral impingement (IFI) is associated with abnormalities of the quadratus femoris muscle and narrowing of the ischiofemoral (IF) and quadratus femoris (QF) spaces. The hip abductors play an important role in pelvic stability and abductor tears might play a role in the pathophysiology of IFI. The purpose of our study was to assess the association between hip abductor tears and IFI on MRI.

MATERIALS AND METHODS

The study was IRB approved and HIPAA compliant. Inclusion criteria were MRI findings of IFI (narrowing of the IF space ≤ 15 mm or QF space ≤ 10 mm with associated ipsilateral quadratus femoris edema or fatty infiltration/atrophy). Two MSK radiologists assessed hip/pelvic MRIs and integrity of the tensor fascia lata, gluteus medius, and minimus tendons. IFI and control groups were compared with a two-tailed Student t test or chi-squared test.

RESULTS

We identified 140 patients with MRI findings of IFI (mean age 56 ± 13 years, 130 f, 10 m) and 140 controls of similar age and sex. Patients with IFI had a higher prevalence of gluteus medius/minimus partial tears (37 vs 21, p = 0.02) and full-thickness tears (24 vs 21, p = 0.03). Patients with IFI had a higher prevalence and higher grade of gluteal muscle atrophy compared with controls (p < 0.03). There were no tears of the tensor fascia lata in either group.

CONCLUSION

Patients with IFI had a higher prevalence of abductor tears and abductor muscle atrophy compared with matched controls. This suggests that abductor tears might play a role in the pathophysiology of IFI.

[Gluteal insufficiency]

Gluteal insufficiency or hip abductor mechanism deficiency mainly following (revision) total hip replacement is associated with highly painful complaints and severe suffering of patients. It represents a great diagnostic and therapeutic challenge. Differentiated conservative treatment pathways, open surgical and endoscopic anatomic repair techniques with intact gluteal musculature and muscle transfer are available as salvage procedures for chronic not anatomically reconstructable mass ruptures. A stepwise diagnostic and therapeutic approach is required for restoration of the quality of life and painless or almost painless mobility of affected patients in occupation and daily life.

Reciprocal relationship between multifidus and psoas at L4-L5 level in women with low back pain

Background Low back pain (LBP) may originate from different sources such as intervertebral disc degeneration (IVDD), end-plate and paraspinal muscle changes. Our aim is to explore the relevance of paraspinal muscles' fat-infiltration in women with LBP and its association with IVDD and Modic changes.Methods Consecutive female patients presenting with chronic LBP to the outpatient clinics were included. Patients were evaluated in terms of IVDD, vertebral end-plate changes, and fatty infiltration in the paraspinal muscles at all lumbar levels on lumbar spine magnetic resonance imaging (MRI). Visual Analogue Scale (VAS) scores were recorded using our prospectively collected database.Results Patients with higher VAS scores were significantly more likely to have more fatty infiltration in the multifidus and less fatty infiltration in the psoas at L4-L5 level when compared to those with lower VAS scores (69.1 vs. 31.8%, p = 0.003). To predict LBP, fatty infiltration in the multifidus and psoas had odds ratio (OR) of 4 (p = 0.010), and 0.3 (p = 0.013), respectively; whereas disc degeneration had an OR of 0.5 (p = 0.028).Conclusion This is the first clinical cross-sectional study suggested that women with chronic low back pain could have less fat-infiltrated psoas to compensate more fat-infiltrated multifidus at L4-L5 disc level.

Equivalent Mid-Term Results of Open vs Endoscopic Gluteal Tendon Tear Repair Using Suture Anchors in Forty-Five Patients

BACKGROUND

Little is known about the relative efficacy of open (OGR) vs endoscopic (EGR) gluteal tendon repair of gluteal tendon tears in minimizing pain and restoring function. Our aim is to compare these 2 surgical techniques and quantify their impact on clinical outcomes.

METHODS

All patients undergoing gluteal tendon tear repair at our institution between 2015 and 2018 were retrospectively reviewed. Pain scores, limp, hip abduction strength, and the use of analgesics were recorded preoperatively and at last follow-up. The Hip disability and Osteoarthritis Outcome Score Junior and Harris Hip Score Section1 were obtained at last follow-up. Fatty degeneration was quantified using the Goutallier-Fuchs Classification (GFC). Statistical analysis was conducted using one-way analysis of variance and t-tests.

RESULTS

Forty-five patients (mean age 66, 87% females) met inclusion criteria. Average follow-up was 20.3 months. None of the 10 patients (22%) undergoing EGR had prior surgery. Of 35 patients (78%) undergoing OGR, 12 (27%) had prior hip replacement (75% via lateral approach). The OGRs had more patients with GFC ≥2 (50% vs 11%, P = .02) and used more anchors (P = .03). Both groups showed statistical improvement (P ≤ .01) for all outcomes measured. GFC >2 was independently associated with a worst limp and Harris Hip Score Section 1 score (P = .05). EGR had a statistically higher opioid use reduction (P < .05) than OGR. Other comparisons between EGR and OGR did not reach statistical significance.

CONCLUSION

In this series, open vs endoscopic operative approach did not impact clinical outcomes. More complex tears were treated open and with more anchors. Fatty degeneration adversely impacted outcomes. Although further evaluation of the efficacy of EGR in complex tears is indicated, both approaches can be used successfully.

Tendon regeneration and muscle hypotrophy after isolated Gracilis tendon harvesting - a pilot study

Purpose

The gracilis tendon (GT) is a commonly used autologous graft in Orthopaedic surgery. The majority of information on knee function and outcomes after hamstring harvest is related to both semitendinosus and GT harvest. Little is known regarding isolated harvest of a GT. It was hypothesized that isolated GT harvest would lead to altered gait patterns (e.g. augmented anterior-posterior translation or rotation in the tibiofemoral joint) and consequently a higher prevalence of cartilage lesions and meniscal tears in knees.

Methods

GT harvesting was performed on patients with chronic acromioclavicular joint instability without previous knee injuries or surgeries. MRI of both knees and thighs were performed. Knee MRI were evaluated using the Whole-Organ Magnetic Resonance Imaging Score (WORMS). Inter- and intraobserver reliabilities, cross-sectional areas of different muscles, fatty infiltration of the gracilis muscle (GM) and GT regeneration were evaluated. The contralateral limb served as reference. The observers were blinded towards the identity of the patients and the operatively treated side.

Results

After a mean time of 44 months after surgery testing was performed on 12 patients. No significant side-to-side differences were found using WORMS, although there was a trend towards increased cartilage lesions after GT harvest (median healthy knee 4.8 and GT harvested knee 7.8 p = 0.086). Inter- and intraobserver repeatability was high with 0.899 (95% confidence interval (CI) 0.708–0.960) and 0.988 (95% CI 0.973–0.995), respectively. A significant hypotrophy of the GM with a mean decrease of 25.3%, 18.4% and 16.9% occurred at 25% (p = 0.016), 50% (p = 0.007) and 75% (p = 0.002) of the length of the femur from distal. No compensatory hypertrophy of other thigh muscles or increased fatty infiltration of the GM was found. Tendon regeneration took place in eight out of 12 patients. In case of regeneration, the regenerated tendon inserted in a more proximal place.

Conclusion

Isolated harvest of the GT for shoulder procedures did not affect knee MRI significantly indicating therefore in general suitable graft utilization for surgeries outside of the knee. GT regenerated in most patients with just a more proximal insertion and a hypotrophy of the muscle belly.

Using the anterior capsule of the hip joint to protect the tensor fascia lata muscle during direct anterior total hip arthroplasty: a randomized prospective trial

BACKGROUND

The direct anterior approach for total hip arthroplasty (THA) has specific advantages, but injury to the tensor fasciae lata muscle (TFLM) remains a concern. This injury in part negates some of the advantages of the intermuscular approach, because injury of the muscle fibers of the TFLM can lead to less satisfactory clinical results. Thus, in this study, we propose an intraoperative method to protect the TFLM and demonstrate its feasibility.

METHODS

Fifty-six patients undergoing THA by the direct anterior approach were divided randomly into two groups. In group A, the TFLM was protected by an autogenous tissue "pad" created from the anterior capsule of the joint which protect the TFLM from direct contact with the retractors. In group B, the operation was carried out with no protection of the TFLM except the attempt by the surgeons to consciously avoid injury of the TFLM. We evaluated magnitude of changes in the muscle cross-sectional area (MSCA) and fatty atrophy (FA) by magnetic resonance imaging. The differences in blood hemoglobin and serum levels of myoglobin, lactate dehydrogenase (LDH), and creatine phosphokinase (CPK) were compared at different time, postoperatively. The Harris hip score, postoperative drainage volume and visual analogue scores (VAS) were compared between the two groups.

RESULTS

LDH, CPK and myoglobin in group B were significantly higher than group A at 8, 24, and 48 h after the surgery. (p < 0.05) Compared to the group A, the decrease of hemoglobin in group B displayed significantly at 24 and 48 h after surgery. (P < 0.05) The significantly increased MSCA and FA of TFLM were demonstrated in group B. The PDV and VAS in group B were significantly higher than group A. (P < 0.05) The Harris score in group A was significantly higher than group B (P < 0.05) one month after surgery, but there was no significant difference six months later.

CONCLUSIONS

Using the anterior capsule of the hip joint as an autogenous, protective capsular tissue pad to limit the trauma to the TFLM during a direct anterior approach to THA is an effective method to protect the TFLM and improve the clinical effect.

TRIAL REGISTRATION

ChiCTR: ChiCTR1900025173. Retrospectively registered August 15, 2019.

Association of Preoperative Gluteal Muscle Fatty Infiltration With Patient Outcomes in Women After Hip Abductor Tendon Repair Augmented With LARS

BACKGROUND

Hip abductor tendon repair has demonstrated encouraging outcomes. The influence of fatty infiltration (FI) on outcome has not been explored.

PURPOSE

To investigate the association between preoperative hip abductor FI and clinical outcome after hip abductor tendon repair.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 84 women underwent hip abductor tendon repair. The mean age was 64.6 years (range, 43-84 years); body mass index, 27.7 (range, 20.0-40.2); and duration of symptoms, 3.4 years (range, 6 months-20 years). The 6-minute walk test, isometric hip abduction strength assessment, and patient-reported outcome measures, including the Harris Hip Score and Oxford Hip Score, were completed presurgery and 2 years after surgery. Patient satisfaction and perceived improvement were assessed 2 years after surgery. All patients underwent preoperative magnetic resonance imaging on the affected hip, and the Goutallier system was used to grade the degree of FI in the anterior, middle, and posterior thirds of the gluteus medius and minimus on a 0-4 ordinal scale. A single FI score for the gluteus medius and minimus was calculated, as was a combined FI score.

RESULTS

All clinical scores significantly improved over time (P < .001). Preoperatively, FI was more severe in the gluteus minimus, with the most severe FI (grades 2-4) demonstrated in the middle (n = 56, 66.7%) and anterior (n = 17, 20.2%) portions of the gluteus minimus and the middle (n = 27, 32.1%) and anterior (n = 12, 14.3%) portions of the gluteus medius. Older age was associated with greater FI (combined FI score: r = 0.529, P < .001), although duration of symptoms (r = 0.035, P = .753) and body mass index (r = 0.089, P = .464) were not. Greater FI was associated with less improvement in hip strength of the unaffected leg (coefficient, -1.6, 95% CI: -2.8 to -0.4), although no other significant associations were observed between FI and pre- or postoperative clinical scores.

CONCLUSION

Preoperative FI was not associated with pertinent parameters of patient outcome after hip abductor tendon repair, including pain, symptoms, functional capacity, perceived improvement, and satisfaction. Based on these outcomes, surgical repair may be considered in the presence of more severe FI.

Quantification of fat in the posterior sacroiliac joint region: fat volume is sex and age dependant

Fat is appreciated as a structural component of synovial joints. It may serve a shock-absorbing function for the incongruent surfaces, vessels and ligaments, but has not been investigated in the posterior sacroiliac joint (PSIJ). Sixty-six cadaveric hemipelves were serially-sectioned and photographed. The amount of visible fat in the PSIJ was quantified using a modified version of Cavalieri’s method. Total volume, fat volume and fat percentage of the PSIJ were calculated in predefined sub-regions. Fat is consistently present in the PSIJ (1.9 ± 1.3 cm³). Fat volume correlates with the PSIJ total volume (p < 0.0001; r = 0.73) and age (p = 0.024; r = 0.24), and is smaller in males (1.4 ± 0.8 cm³) than females (2.4 ± 1.5 cm³). Fat volumes in the middle and inferior sub-regions of the PSIJ show side- (p < 0.0001) and sex-differences (p = 0.013 females, middle sub-region). Age and PSIJ total volume correlate between sexes in various sub-regions (p = 0.05 females superior sub-region; males inferior sub-region). Fat percentage differs between sexes and sub-regions (p = 0.018 females, superior sub-region) but is independent of age and sides. The presence of fat within the PSIJ is a normal finding and shows sex-dependant and age-related differences. It is unclear whether fat is linked to age-related degeneration or has a shock-absorbing role in stress- and load-dissipation in the PSIJ.

[Surgical repair of gluteus medius muscle in hip replacement surgery]

Injury of gluteus medius muscle is a serious often complication after hip replacement surgery followed by pain, claudication and significant deterioration of the quality of life. Prevention of intraoperative injury of this muscle is especially relevant in young patients. Normal function of this muscle provides rapid rehabilitation and early postoperative recovery. However, hip replacement surgery through Hardinge's direct lateral approach is accompanied by fatty degeneration of gluteus medius muscle in 12-20% of cases. Moreover, two or more redo procedures lead to fatty degeneration of almost 70% of anterior and 40% of central muscular segment. Currently, there are many methods of surgical treatment of this complication including transosseous muscle fixation, endoscopic procedures, repair using Achilles tendon, gluteus maximus muscle, lateral head of quadriceps muscle and allografts. However, various publications devoted to this problem have certain disadvantages including short follow-up period, small sample size and often unsatisfactory outcomes. Therefore, the question of surgical repair of hip abductor function remains open.

ESB Clinical Biomechanics Award 2018: Muscle atrophy-related increased joint loading after total hip arthroplasty and their postoperative change from 3 to 50 months

BACKGROUND

Hip joint loading is dominated by muscular activity. Thus, contact forces exceeding many times one's body weight are a consequence of imbalanced muscular activity. The objective was to analyze the influence of muscle atrophy after total hip arthroplasty on in vivo hip joint contact loading initially and long term. We hypothesized that an impaired periarticular muscle will lead to increase in vivo joint load, specifically in the long term.

METHODS

Using a group of nine patients with instrumented hip implants, contact forces and muscle status were analyzed one day prior to 3 and 50 months after joint arthroplasty. In vivo load measurements were performed for different activities of daily living (ADL). Pre- and postoperative pelvic CT scans were analyzed to assess the periarticular muscle status. Finally, the muscle morphologies and in vivo contact forces were compared.

RESULTS

At 3 months after total hip arthroplasty we found a significant correlation of lower lean gluteus minimus muscle (GMin) volume with higher loads during all tested activities of daily living. 50 months postoperatively statistical analysis revealed lower lean volume of the gluteus maximus to be correlated with higher joint loads in walking.

CONCLUSION

Our data generally show a good comparability between muscle status and joint contact forces and thus support our hypothesis that an impairment of periarticular musculature contributes to an increase of the in vivo joint loads after total hip arthroplasty. Effects were most pronounced during stair climbing and sit-down/stand-up from a chair at 3 months and during level walking at 50 months.

Quantification of shoulder muscle intramuscular fatty infiltration on T1-weighted MRI: a viable alternative to the Goutallier classification system

BACKGROUND

Quantification of rotator cuff intramuscular fatty infiltration is important for clinical decision-making in patients with rotator cuff tear. The semi-quantitative Goutallier classification system is the most commonly used method, but has limited reliability. Therefore, we sought to test a freely available fuzzy C-means segmentation software program for reliability of the quantification of shoulder intramuscular fatty infiltration on T1-weighted MR images and for correlation with fat fraction by six-point Dixon MRI.

MATERIALS AND METHODS

We performed a prospective cross-sectional study to measure visible intramuscular fat area percentage on oblique sagittal T1 MR images by fuzzy C-means segmentation and fat fraction maps by six-point Dixon MRI for 42 shoulder muscles. Intra- and inter-observer reliability were determined. Correlative analysis for fuzzy C-means and six-point Dixon intramuscular fatty infiltration measures was also performed.

RESULTS

We found that inter-observer reliability for the quantification of visible intramuscular fat area percentage by fuzzy C-means segmentation and fat fraction by six-point Dixon MRI was 0.947 and 0.951 respectively. The intra-observer reliability for the quantification of visible intramuscular fat area percentage by fuzzy C-means segmentation and fat fraction by six-point Dixon MRI was 0.871 and 0.979 respectively. We found a strong correlation between fuzzy C-means segmentation and six-point Dixon techniques; r = 0.850, p < 0.001 by individual muscle; and r = 0.977, p < 0.002 by study subject.

CONCLUSION

Quantification of intramuscular fatty infiltration by fuzzy C-means segmentation on T1-weighted sequences demonstrates excellent reliability and strong correlation with fat fraction by six-point Dixon MRI. Quantitative fuzzy C-means segmentation is a viable alternative to the semi-quantitative Goutallier classification system.

Muscle size and composition in people with articular hip pathology: a systematic review with meta-analysis

OBJECTIVE

To synthesise and evaluate the current evidence investigating muscle size and composition in non-inflammatory articular hip pathology.

METHODS

A systematic review of five electronic databases, using three concepts; articular hip pathology (e.g., osteoarthritis (OA)); hip muscles; and outcomes (e.g., muscle size and adiposity) was undertaken. Studies addressing non-inflammatory or non-traumatic articular hip pain, using measures of muscle size and adiposity were included and appraised for risk of bias. Data was extracted to calculate standardised mean differences (SMD) and pooled where possible for meta-analysis.

RESULTS

Thirteen cross-sectional studies were included; all studies measured muscle size and 5/13 measured adiposity. In OA, there was low to very low quality evidence of no difference in hip muscle size, compared with matched controls. In unilateral OA, there was low to very low quality evidence of smaller size in gluteus minimus (SMD -0.38; 95% confidence interval (CI) -0.74, -0.01), gluteus medius (-0.44; 95% CI: -0.83, -0.05) and gluteus maximus (-0.39; 95% CI: -0.75, -0.02) muscles in the symptomatic limb. Individual studies demonstrated non-uniform changes in muscle size in OA. No significant difference was observed in muscle size in other pathologies or in adiposity for any group.

CONCLUSION

There is some low quality evidence that specific hip muscles are smaller in unilateral hip OA. Variation in the magnitude of differences indicate changes in size are not uniform across all muscles or stage of pathology. Studies in larger cohorts investigating muscle size and composition across the spectrum of articular pathologies are required to clarify these findings.

Peroneal Tendon Tears: We Should Consider Looking at the Muscle Instead

INTRODUCTION

The purpose of this study was to determine whether tears of the peroneus brevis (PB) tendon correlate with increased fatty infiltration of the PB muscle on MRI compared with musculature without clinical evidence of peroneal pathology.

METHODS

Ankle MRI scans of patients with PB tendon tearing (tear group) were compared with those of patients without clinical evidence of peroneal pathology (control group). Two reviewers graded the PB muscle belly according to the Goutallier classification.

RESULTS

Thirty patients were included in each group. The mean Goutallier scores for the tear and control groups were 0.52 (±0.72) and 0.05 (±0.15), respectively (P = 0.0019). The level of interobserver agreement between reviewers was moderate (intraclass correlation coefficient = 0.75; 95% confidence interval, 0.57 to 0.85).

DISCUSSION

Patients with PB tendon tear demonstrate markedly higher grades of fatty degeneration compared with patients without peroneal pathology. The Goutallier classification may become a valuable instrument for assessing the severity of a PB tear.

LEVEL OF EVIDENCE

Level III-diagnostic study.

Severe Lumbar Intervertebral Disc Degeneration Is Associated with Modic Changes and Fatty Infiltration in the Paraspinal Muscles at all Lumbar Levels, Except for L1-L2: A Cross-Sectional Analysis of 50 Symptomatic Women and 50 Age-Matched Symptomatic Men

BACKGROUND

Low back pain is a common public health problem associated with lumbar intervertebral disc degeneration. It is still unclear, however, whether intervertebral disc degeneration is an isolated process or accompanied by other degenerative events. We analyzed whether disc degeneration was associated with vertebral end-plate changes and fatty infiltration in the paraspinal muscles. We also aimed to identify whether the severity of disc degeneration influenced this association.

METHODS

Intervertebral disc degeneration, vertebral end-plate changes, and fatty infiltration in the multifidus, erector spinae, and psoas muscles at all lumbar intervertebral disc levels were evaluated on lumbar spine magnetic resonance images of 50 symptomatic women and 50 age-matched symptomatic men.

RESULTS

The women had greater lumbar intervertebral disc degeneration scores at L4-L5 and L5-S1 and in total. The women had more fatty infiltration in the multifidus and erector spinae muscles at L4-L5 and L5-S1. The men had more fatty infiltration in the psoas muscle at L5-S1. Patients with severe intervertebral disc degeneration were more likely to have increased fatty infiltration in the multifidus and erector spinae muscles. The rate of vertebral end-plate changes was also greater in the patients with severe intervertebral disc degeneration.

CONCLUSIONS

Severe disc degeneration in the lumbar spine is closely associated with Modic changes and fatty infiltration in the multifidus and erector spinae muscles. We suggest that disc degeneration is not an isolated event but, rather, a continuum of events that could more clearly be shown in future prospective, large sample-size studies.

[Surgical refixation of gluteal tendon tears by mini-open double-row technique]

OBJECTIVE

Stable refixation of gluteal tendons at the anatomic footprint by large-area contact by the means of knotless double-row anchor fixation (HipBridge technique).

INDICATIONS

Symptomatic tear of gluteus medius and/or gluteus minimus tendon with persisting pain after nonsurgical treatment, or primarily reconstructable mass rupture with gluteal insufficiency, revision surgeries.

CONTRAINDICATIONS

Primary nonreconstructable mass ruptures, atrophic or fatty degeneration of gluteal muscles grade Goutallier 4, local infections.

SURGICAL TECHNIQUE

Lateral position, longitudinal skin incision over greater trochanter, longitudinal incision of iliotibial band, resection of trochanteric subgluteus maximus bursa, longitudinal splitting of gluteal tendons over tear, debridement and mobilisation of tendons for sufficient distalisation to tendon footprint at anterior and lateral trochanteric facet, debridement of sclerotic greater trochanter, punching and tapping of proximal row, placement of two proximal anchors loaded with nonresorbable suture tape, fan-shaped four times gluteal tendon perforation at myotendinous transition zone, double-V-shape crossing of suture tapes, punching and tapping of distal row, fixation of crossed tapes with two distal knotless suture anchors under mild pretensioning of gluteal tendons, side-to-side tendon suture, vastogluteal and iliotibial band closure, wound closure.

POSTOPERATIVE MANAGEMENT

Stage-dependent physiotherapy with partial weight-bearing with 20 kg for 6 weeks, no active abduction, no adduction and no external rotation in flexion for 6 weeks after surgery. From week 7 after surgery, free range of motion, active-assisted abduction and increase in weight-bearing by 15 kg/week. No peak load for 4 months. Thromboembolic prophylaxis until full weight-bearing is reached.

RESULTS

Success rates of 80-90% can be expected in cases with no or only minor muscle atrophy.

Immunomodulatory placental-expanded, mesenchymal stromal cells improve muscle function following hip arthroplasty

BACKGROUND

No regenerative approach has thus far been shown to be effective in skeletal muscle injuries, despite their high frequency and associated functional deficits. We sought to address surgical trauma-related muscle injuries using local intraoperative application of allogeneic placenta-derived, mesenchymal-like adherent cells (PLX-PAD), using hip arthroplasty as a standardized injury model, because of the high regenerative and immunomodulatory potency of this cell type.

METHODS

Our pilot phase I/IIa study was prospective, randomized, double blind, and placebo-controlled. Twenty patients undergoing hip arthroplasty via a direct lateral approach received an injection of 3.0 × 10⁸ (300 M, n = 6) or 1.5 × 10⁸ (150 M, n = 7) PLX-PAD or a placebo (n = 7) into the injured gluteus medius muscles.

RESULTS

We did not observe any relevant PLX-PAD-related adverse events at the 2-year follow-up. Improved gluteus medius strength was noted as early as Week 6 in the treatment-groups. Surprisingly, until Week 26, the low-dose group outperformed the high-dose group and reached significantly improved strength compared with placebo [150 M vs. placebo: P = 0.007 (baseline adjusted; 95% confidence interval 7.6, 43.9); preoperative baseline values mean ± SE: placebo: 24.4 ± 6.7 Nm, 150 M: 27.3 ± 5.6 Nm], mirrored by an increase in muscle volume [150 M vs. placebo: P = 0.004 (baseline adjusted; 95% confidence interval 6.0, 30.0); preoperative baseline values GM volume: placebo: 211.9 ± 15.3 cm³ , 150 M: 237.4 ± 27.2 cm³ ]. Histology indicated accelerated healing after cell therapy. Biomarker studies revealed that low-dose treatment reduced the surgery-related immunological stress reaction more than high-dose treatment (exemplarily: CD16+ NK cells: Day 1 P = 0.06 vs. placebo, P = 0.07 vs. 150 M; CD4+ T-cells: Day 1 P = 0.04 vs. placebo, P = 0.08 vs. 150 M). Signs of late-onset immune reactivity after high-dose treatment corresponded to reduced functional improvement.

CONCLUSIONS

Allogeneic PLX-PAD therapy improved strength and volume of injured skeletal muscle with a reasonable safety profile. Outcomes could be positively correlated with the modulation of early postoperative stress-related immunological reactions.