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Influence of Muscle Fatty Degeneration on Functional Outcomes After Endoscopic Gluteus Medius Repair
Original Article With Video Illustration
Influence of Muscle Fatty Degeneration on Functional Outcomes After Endoscopic Gluteus Medius Repair Mathieu Thaunat, M.D., Gilles Clowez, M.D., Antoine Desseaux, M.D., Colin G. Murphy, M.D., Mouhcine Sbiyaa, M.D., Eric Noël, M.D., and Bertrand Sonnery-Cottet, M.D.
Purpose: To report the early outcomes of endoscopic repair of tears of the gluteus medius tendon and to determine whether the fatty degeneration had an influence on clinical results. Methods: Between October 2012 and June 2014, data were prospectively collected and retrospectively reviewed for all patients who underwent endoscopic gluteus medius repair. Patients were assessed pre- and postoperatively using the modified Harris hip score, the nonarthritic hip score, and visual analog scale for pain. The gluteus minimus and the 3 distinct parts of the gluteus medius (anterior, middle, and posterior) were assigned a grade of fatty degeneration on preoperative magnetic resonance imaging scans. Results: Twenty-two hips (in 20 patients) were assessed with the mean follow-up of 31.7 months (range: 24 to 47 months). There were 15 partial-thickness and 7 full-thickness tears. No patient was lost to follow-up. The mean age at the time of surgery was 66 years (range: 45 to 82 years). Of the 20 magnetic resonance imagingeassessed hips included in the study, 14 had fatty degeneration of the gluteus medius (partial-thickness tears: n ¼ 8, full-thickness tears: n ¼ 6). The mean gluteus medius fatty degeneration index was 1.57 (range: 0.33 to 3.33). Postoperative improvement was seen in modified Harris hip score (33.7 points vs 80.2 points, P ¼ .0001), nonarthritic hip score (47.7 points vs 76.8 points, P ¼ .0001), and in the visual analog scale for pain (7.2 vs 3.2, P < .05). Increasing preoperative fatty degeneration index of the gluteus medius correlated with decreased postoperative functional hip score values (regression coefficient, 0.5839; P < .0001). Tear characteristics (partial or full-thickness) did not correlate with fatty degeneration or muscular atrophy and did not affect postoperative outcomes. Conclusions: Endoscopic surgical repair can be an effective treatment of gluteus medius tears in the short term. Fatty degeneration of the gluteus medius and minimus has a negative impact on clinical outcomes of endoscopic gluteus medius repair. Level of Evidence: Level IV, therapeutic case series (no control group).
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luteus medius and minimus tendon tears had been recognized as a major cause of recalcitrant greater trochanteric pain syndrome.1-3 Some authors have compared gluteus medius and minimus tendon insertions on the greater trochanter (GT) with those of
From the Ramsay Générale de Santé, Hôpital Privé Jean Mermoz, Centre Orthopédique Santy, Lyon, France. The authors report the following potential conflicts of interest or sources of funding: M.T. and B.S-C. receive consulting fee from Arthrex. G.C. and A.D. had 6-month fellowships sponsored by Arthrex in Centre Orthopédique Santy, Lyon. Full ICMJE author disclosure forms are available for this article online, as supplementary material. Received January 15, 2017; accepted January 2, 2018. Address correspondence to Mathieu Thaunat, M.D., Centre Orthopédique Santy, 24, Avenue Paul Santy, 69008 Lyon, France. E-mail: [email protected] Ó 2018 by the Arthroscopy Association of North America 0749-8063/1736/$36.00 https://doi.org/10.1016/j.arthro.2018.01.005
the rotator cuff on the humerus greater tuberosity, leading to define hip abductor tears as “rotator cuff tears of the hip.”1,4-6 Tears in the gluteus medius and minimus tendons have been recognized as an important cause of recalcitrant greater trochanteric pain syndrome. Because of the frequency of partialthickness undersurface tears, this relatively unknown pathology is often misdiagnosed and left untreated.7 Surgery is indicated in case of 4 associated conditions: (1) duration of symptoms greater than 6 months, (2) magnetic resonance imaging (MRI) showing a tendon tear, (3) positive ultrasound-guided infiltration test, and (4) the absence of either retraction of or an evolved fatty degeneration of the gluteus medius and minimus muscles.5 Goutallier was the first to highlight the link between preoperative muscle fatty degeneration and poor outcomes after rotator cuff repair.3 These findings seem to extend to the repair of the hip abductor muscles.8,9 Endoscopic repair of partial- or full-thickness
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tear resistant to conservative treatment seems to give satisfactory results,10 but to date, only one study has examined the influence of muscular fatty degeneration on the functional results of endoscopic repair of gluteus medius tendon tears.8 The purpose of our study was to report the early outcomes of endoscopic repair of partial- and fullthickness tears of the gluteus medius tendon and to determine whether the fatty degeneration had an influence on clinical results. Our main hypothesis was that endoscopic surgical repair would be an effective treatment of greater trochanteric pain syndrome associated with gluteus medius tears but that fatty degeneration severity of the gluteus minimus and medius affects clinical outcomes.
Methods Patient Selection A retrospective analysis of prospectively collected data was performed of patients who underwent hip endoscopy for greater trochanteric tendinobursitis recalcitrant to medical treatment between October 1, 2012, and June 30, 2014, by one senior surgeon (M.T.). The flow of patients is shown in Figure 1. Continuous series of 22 endoscopic gluteus medius tendon repairs with the same surgical procedure were eligible for evaluation. Inclusion criteria were hip abductor tendon repair and a minimum of 2 years’ follow-up from index surgery. Exclusion criteria were ipsilateral osteoarthritis of the hip and previous hip surgery. Preoperative diagnosis was based on clinical examination, radiograph, and MRI findings. These patients had persistent pain over the GT, symptoms compatible with hip abductors tendinobursitis, such as pain at ipsilateral unipodal weight bearing, and other positive clinical findings described by Lequesne.11 Indications for surgery were chronic pain and disability with clinical and MRI findings compatible with abductor tendon tear associated with failure of 6 months of conservative measures that included anti-inflammatory drugs, physical therapy, and corticosteroid injections. Preoperative MRI showed 7 full-thickness tears and 15 partial tears of hip abductor tendons. Surgical Technique Under a general anesthesia with the patient in the lateral decubitus position, the hip was help in 20 abduction (with pillow bolters). The whole operated limb was included in the surgical field. Three portals were routinely performed (1 distal, 2 proximal), but supplementary portals could be added as required. The iliotibial band was opened in a cruciform fashion 5 cm proximally and distally to the summit of the GT, and the subtrochanteric bursa was then resected. The tendons
Hip endoscopy for recalcitrant GTPS n=25
Endoscopic Gluteus medius repair n=23
Inclusion criteria n=22
Lost to FU n=0
Exclusion criteria n=1
Isolated bursectomy n=2
Fig 1. Patient flow through the study. (FU, follow-up; GTPS, greater trochanteric pain syndrome.)
were inspected and palpated with a palpation hook to identify lesions. The intraoperative tear patterns and the macroscopic appearance of the tendons were recorded. Pathologic tissue was removed using shaver down to the healthy tissue. In case of suspicion of a partial-thickness tear, a transtendinous approach was performed.12 Then the GT was abraded using a motorized burr. All aggressive osteophytes had to be removed and the bald zone of GT’s summit had to be reduced.9 Side-to-side repair was performed using 1 or 2 anchors (U-shaped, with 2 to 4 sutures). In cases of full-thickness tears, double-row repair with suture bridging was used to increase the contact area of the tendon along the anatomic footprint (Fig 2). The iliotibial band was left open at the end of the procedure. No drains were required because blood loss was minimal (Video, available at www.arthroscopyjournal.org). Postoperative Management Rehabilitation was initiated immediately with nonweight-bearing for 6 weeks, avoiding passive lateral rotation, passive adduction, active internal rotation, and active abduction for the first 6 weeks. An abduction brace had to be worn between sessions. Hip motion was extended up to 90 flexion for the first 3 weeks. At 6 weeks, weight bearing was progressively resumed. By 6 months, gait had to be normal and painless. Data Collection Preoperative clinical data were registered at a clinic visit. Visual analog scale for average pain on a numeric scale from 0 to 10 (0 ¼ no pain), 2 functional hip scores, the modified Harris hip score (MHHS),13 the nonarthritic hip score (NAHS),14 body mass index, and the date of early symptoms were collected. Postoperative data added a patient-rated overall satisfaction score (PROS) on a numeric scale from 1 to 10 (10 ¼ extremely satisfied), which enquired if the patient could lie on the operated side and if the patient had forgotten the operated hip. Data were collected at a preoperative clinic visit, 1 year postoperatively, and at the last follow-up either at a clinic visit or by a phone call.
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Fig 2. Arthroscopic view of gluteus medius repair. (A, B) Partial thickness tear of the lateral lamina of the gluteus medius tendon repaired in a side-to-side fashion. (C, D) Speedbridge (Arthrex, Naples, FL) suture repair of a retracted fullthickness tear of the lateral lamina of the gluteus medius tendon. (GMed T, gluteus medius tendon; GT, greater trochanter.)
MRI was systematically performed preoperatively. Transverse, coronal, and sagittal T2-weighted images were used to assess hip abductor tendon type of tear (full- or partial-thickness tear) and trochanteric bursitis. Gluteus minimus and medius fatty degeneration were assessed on the first transverse nonefat-suppressed T1weighted slice below the ipsilateral sacroiliac joint. According to the Goutallier-Fuchs classification,15-17 fatty degeneration was graded for the whole gluteus minimus and for each of the 3 facially distinct parts of the gluteus medius18,19 (Fig 3). Like the Goutallier rotator cuff global fatty degeneration index,17 adding the mean grade value of each part of the muscle determined a gluteus medius fatty degeneration index (GmedFDI). The abductor muscle was deemed atrophic if the size of one or more of its constituent parts size had decreased by at least 25% compared with the contralateral side.20 MRI was performed at 1 year postoperatively to assess tendon healing. Statistical Analysis All data were analyzed with the free collaborative online software EasyMadeStat.com (Easy Made Stat, Neuilly-sur-Seine, France). Variable comparisons were analyzed using the Wilcoxon signed-rank test and Mann-Whitney nonparametric test. The Pearson correlation coefficient was used to find numeric correlation between fatty degeneration of hip abductor muscles and clinical variables. Statistical significance was defined as P < .05.
Results Study Population Between October 2012 and June 2014, 22 hips for 20 patients met the inclusion criteria. Demographic data are summarized in Table 1. The mean follow-up was 31.7 months with a minimum of 24 months (range: 24-47 months). All patients described a progressive onset of symptoms without a history of defined trauma. No patient was lost to follow-up. Clinical Assessment The patients were all reviewed with minimum 2 years’ follow-up and all completed the postoperative questionnaire at a clinic visit or by a phone call. A full set of completed clinical scores and questionnaires (MHHS, NAHS, visual analog scale, PROS) was available for all patients (Table 2). From preoperative to most recent follow-up, there was significant improvement for both hip scores (Fig 4). Patients’ age at surgery, preoperative duration of symptoms, and body mass index did not correlate with pre- and postoperative hip scores (P > .05). Patients reported an overall postoperative satisfaction of 7 (range: 3 to 10). Four operated hips (18%) were reported “forgotten” by the patient. Ten patients (45%) could lie down without pain on the operated side. MRI Assessment Two patients could not pass pre- and postoperative MRI because of the implantation of a pacemaker and were
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Fig 3. Fatty degeneration assessment of the gluteus medius and minimus muscle. (A) Gluteus medius and minimus fatty degeneration were assessed on the first transverse nonefat-suppressed T1-weighted slice below the ipsilateral sacroiliac joint. According to the Goutallier-Fuchs classification, fatty degeneration was graded for all of gluteus minimus and for each of the 3 facially distinct parts of the gluteus medius. Fatty degeneration index (FDI) of the gluteus medius muscle was evaluated adding the mean grade value of each part of the muscle. (B) Normal aspect of the gluteus minimus (GMi), gluteus maximus (GMa), and the 3 distinct parts of the gluteus medius (anterior part [GMeA] circled in blue, middle part [GMeM] circled in yellow, and posterior part [GMeP] circled in red). The FDI is 0.2. (C) Example of a grade 3 fatty degeneration (as much fat as muscle) involving the anterior and the middle part of the gluteus medius muscle. The FDI is 2.7.
Table 1. Epidemiological Factors Patients, n Sex, n Male Female Age (yr), mean SD Height (cm), mean SD Weight (kg), mean SD BMI, mean SD Hips, n Side of surgery, n Left Right Duration of symptoms (yr), mean SD Follow-up (mo), mean SD BMI, body mass index; SD, standard deviation.
20 3 (15%) 17 (85%) 66 8.0 164 6.2 74 13.7 27.6 4.9 22 16 6 3.5 3.2 31.7 7.6
followed with echography. Both were excluded from the MRI data analysis. MRI data were available for 20 hips. Fourteen hips (70%) had fatty degeneration of the gluteus medius. Mean GmedFDI was 1.57 (range: 0.33 Table 2. Clinical Outcomes Parameter MHHS, mean SD NAHS, mean SD VAS, mean SD PROS, mean SD
Preoperative (n ¼ 22) 33.7 8.7 47.7 7.7 7.2 1.0 e
Last Follow-up (n ¼ 22) 80.2 19.4 76.8 14.5 3.2 2.8 7.0 2.3
P Value .0001 .0001 <.05 e
MHHS, modified Harris hip score; NAHS, nonarthritis hip score; PROS, patient-rated overall satisfaction; SD, standard deviation; VAS, visual analog scale.
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Improvements between pre- and postoperative hip score values were significantly higher in the group with either no or one gluteus medius fatty degenerated part when compared with patients with 2 or 3 distinct parts of the gluteus medius muscle affected by fatty degeneration (Fig 6). No differences were noted in the pre- and postoperative scores between the group “no muscular atrophy” and the group “muscular atrophy” (Table 3) or between the group “partial-thickness tear” and the group “full-thickness tear” (Table 4). The small sample size did not allow us to find any correlation between muscular atrophy or fatty degeneration and the completeness of the rupture. Fig 4. Comparison between preoperative and last follow-up functional scores. Values are expressed as mean SD. (MHHS, modified Harris hip score; NAHS, nonarthritic hip score; SD, standard deviation; VAS, visual analog scale.)
to 3.33). Five hips were Goutallier grade 1, 5 were grade 2, 3 were grade 3, and 1 hip was grade 4. Only one of the 3 parts of the gluteus medius was degenerative for 3 hips; 2 parts for 8 hips and the 3 parts of the muscle were degenerative for 3 hips. Preoperative MRI showed gluteus medius muscular atrophy for 6 hips (30%). For these atrophic hips, the mean GmedFDI was 2.22 (range: 0.67 to 3.33) compared with a mean GmedFDI of 1.08 (range: 0.33 to 2.67) for hips without gluteus medius atrophy. For the patients who had fullthickness tears of the gluteus medius, the mean GmedFDI was 1.56 (range: 0 to 3.3) compared with a mean GmedFDI of 0.9 (range: 0 to 1.33) for hips with partial-thickness tears of the gluteus medius (P > .05). Eighteen hips (90%) had fatty degeneration of the gluteus minimus. Two hips were Goutallier grade 1, 8 were grade 2, 6 were grade 3, and 2 were grade 4. The mean gluteus minimus fatty degeneration (GminFD) grade was 2.44. Postoperative MRI results showed 1 failure of partial tendon repair in a female patient, but otherwise 19 of 20 hips showed tendon healing at 1 year. Clinical and MRI Outcome Analysis GmedFDI was strongly negatively correlated with the postoperative MHHS value (R2 ¼ 0.58; P < .0001), NAHS value (R2 ¼ 0.51; P ¼ .0004) (Fig 5), and also with PROS (R2 ¼ 0.57; P < .005). As GmedFDI increased, the values of postoperative MHHS, NAHS, and PROS tended to decrease. GminFD was also negatively correlated with the postoperative MHHS value (R2 ¼ 0.30; P ¼ .0118), NAHS value (R2 ¼ 0.41; P ¼ .0023), and also with PROS (R2 ¼ 0.44; P < .05). As GminFD increased, the values of postoperative MHHS, NAHS, and PROS tended to decrease.
Complications We did not identify any wound problems, infection, or nerve injury. Postoperative MRI results showed 1 failure of tendon repair in a patient.
Discussion The principal findings of our study are that (1) endoscopic gluteus medius tear repair improves overall functional outcomes and patient satisfaction, and (2) functional outcomes and patient satisfaction significantly decrease as preoperative fatty degeneration for both gluteus minimus and medius increases. In 1999, Kagan4 published the first case series with results on open surgical repair of the gluteus medius tendon, noting excellent results at long-term follow-up. Novel endoscopic techniques for the treatment of extraarticular abnormalities of the hip have been reported, including descriptions of endoscopic repair of gluteus medius tears with excellent results and more notably with fewer complications.21-24 However, the fatty degeneration of the gluteus muscle has not been investigated in these studies. Our study shows similar
Fig 5. Correlation between fatty degeneration of the gluteus medius at the time of repair and functional result at the last follow-up. Gluteus medius fatty degeneration index (GmedFDI) was strongly negatively correlated with postoperative modified Harris hip score (MHHS) and nonarthritic hip score (NAHS).
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Fig 6. Patients with no fatty degeneration or 1 fatty degenerated part of the gluteus medius muscle had a significantly higher gain in functional score (MHHS and NAHS) than patients with 2 or 3 fatty degenerated parts of the gluteus medius muscle. (MMHS, modified Harris hip score; NAHS, nonarthritic hip score.)
functional results after endoscopic repair to those previously published. Gluteal muscle atrophy and type of tear (partial-thickness or full-thickness) were also evaluated. Our small sample could not make it possible to highlight a statistical link between full-thickness tears and muscular atrophy or fatty degeneration. Indeed, contrary to the natural evolution of the tendon lesions in the shoulder, these tendons may undergo a gradual process of degeneration with repetitive injury and repair leading to dysfunction and atrophy rather than rupture.25 Some tendons are prone to complete tears, whereas others degenerate with thickening and subsequent fraying, partial-thickness tearing, and thinning with associated muscle atrophy and dysfunction.25 As already described in shoulders,26 our results suggest that there is a correlation between poor clinical results and the extent of fatty degeneration in the different muscle bellies of the gluteus medius muscle.
Although better known for the shoulder, hip abductor muscle fatty degeneration and atrophy are well identified and quantified with MRI.9,25,27-29 Studies with visual fatty degeneration assessment have been mainly reported in the context of patients who were operated for a total hip arthroplasty9,27 or in a context of osteoarthritis28 and usually used several transverse MRI slices. We identified only 2 studies that assessed hip abductor muscle fatty degeneration before surgical repair of the gluteus medius tendon.8,30 Makridis et al.30 reported 20% of patients with hip abductor muscle fatty degeneration in a cohort of 67 patients who underwent an open double-row tendon repair. Muscle atrophy was a predictor of bad prognosis in their study. However, no significant changes in the postoperative clinical outcomes were reported between patients with hip abductor fatty degeneration and patients without.30 Bogunovic et al.8 previously reported
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ENDOSCOPIC GLUTEUS MEDIUS REPAIR Table 3. Pre- and Postoperative Hip Score Values Depending on Gluteus Medius Trophicity
GmedFDI, mean SD MHHS Preop., mean SD Postop., mean SD P value NAHS Preop., mean SD Postop., mean SD P value
Atrophic, n¼6 2.22 0.9
Nonatrophic, n ¼ 14 0.62 0.8
33.3 10.5 70.2 20.7 <.05
34.6 8.7 82.7 18.8 <.05
>.05 >.05
45.8 10.3 69.8 12.3 <.05
48.9 7.1 79.3 15.7 <.05
>.05 >.05
P Value <.01
GmedFDI, gluteus medius fatty degeneration index; MHHS, modified Harris hip score; NAHS, nonarthritis hip score; SD, standard deviation.
similar results to ours after endoscopic repair of the gluteus tendon, finding that an increase in preoperative hip abductor muscle fatty degeneration is correlated with poor outcomes; however, they reported an 80% rate of associated intra-articular procedures such as labral debridement, repair, and cam/pincer decompression. In this latter study, the fatty degeneration of the gluteus medius muscle was assessed on a unique coronal slice. We believe that only transverse T1 slice allows a good complete anterior-posterior analysis of the 3 anatomical parts of the gluteus medius well described by Gottschalk et al.18 It allows analyzing fatty degeneration not only in terms of severity according to the Goutallier-Fuchs classification but also in terms of extension to the entire muscle, which, we believe, has never been proposed. Studies highlight that it is common to observe a slight fatty degeneration of all gluteal muscles even in a healthy population, but rarely more than low grades and mostly corresponding to Goutallier grade 1.9,28,29 Engelken et al.9 reported minor fatty degeneration of the gluteus minimus, equivalent to Goutallier grade 1 in their asymptomatic control group; however, in this study, the mean age of the control group was 31.2 years compared with 64.9 years for the symptomatic group. Marcon et al.29 also found no age dependence in hip abductor fatty degeneration in healthy volunteers. Other studies report opposite results with muscle fatty degeneration increasing with age.25,31 Because the natural history of these lesions is different from those observed in the shoulder (frequency of partial thickness lesions at the time of repair), it seems important to define the thresholds in terms of age and fatty degeneration (extension and severity) constituting a contraindication for tendon repair and when a limited endoscopic bursectomy should be proposed instead. Although endoscopic gluteus medius repair seems to show good preliminary outcomes, similarly effective to open repair and with less complication rates,21-24,30,32
many of our patients have reported less optimistic outcomes and one patient in our series had a failure of tendon healing on postoperative MRI. The rate of tendon retear after open repair was between 9% and 11% in studies with a large sample size and a longer follow-up,22 and the lower rate reported in endoscopic studies is probably linked to the small sample and short follow-up. Several studies have noted the degenerative condition of the gluteal tendons at the time of repair, and this may be a predisposing factor for retears.22 The degree of tendon degeneration may compromise the tissue left for reattachment, raising concerns over its healing capacity, durability, and ultimate strength. Hence, we believe that the GT abrasion is an essential step and could be compared with the acromioplasty performed during a rotator cuff repair in the shoulder. A cortical bone abrasion should be carried out with the high-speed burr until bleeding cancellous bone is present not only to stimulate a biologic response but also to remove all aggressive osteophytes. The bald zone of summit of the GT must be reduced, as most lesions are located on the deep side of the lateral lamina of the gluteus medius: presumably, the GT aggresses the tendon and is implicated in these partial-thickness lesions by a “wiper” effect during rotation.5,10 Limitations The retrospective nature, the absence of comparative group, the small sample size, and the short follow-up of this study are its main limitations. However, the low number of patients in our series makes the analysis of the gluteus medius fatty degeneration extent in subgroups at risk of statistical error. Thus, subgroups are so small that it is possible that a different result in as few as one additional patient could change the conclusion. Furthermore, and perhaps as a result of the small groups, although we do show statistical differences, the overlapping confidence intervals suggest no clinical differences between groups. However, current studies devoted to endoscopic repair of the gluteal muscle also Table 4. Pre- and Postoperative Hip Score Values Depending on the Type of Hip Abductor Tear
GmedFDI, mean SD MHHS Preop., mean SD Postop., mean SD P value NAHS Preop., mean SD Postop., mean SD P value
Full-thickness Tear, n ¼ 6 1.56 1.3
Partial-thickness Tear, n ¼ 14 0.9 0.9
35.9 7.4 74.3 20.4 <.05
32.7 9.4 83.0 18.8 <.05
>.05 >.05
48.5 7.5 71.6 11.4 <.05
47.3 8.0 79.2 15.4 <.05
>.05 >.05
P Value >.05
GmedFDI, gluteus medius fatty degeneration index; MHHS, modified Harris hip score; NAHS, nonarthritis hip score; SD, standard deviation.
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have low numbers of patients. In addition, greater trochanteric pain syndrome and gluteal tendon tears may be more symptomatic or more prevalent in women, but the uneven gender distribution in this study does limit the generalizability of the results. We report only one case of tendon repair failure but given that several patients reported poorer outcomes scores, it is possible that other retears occurred later without MRI proof.
Conclusions This study suggests that endoscopic surgical repair can be an effective treatment of gluteus medius tears in the short term. Fatty degeneration of the gluteus medius and minimus has a negative impact on clinical outcomes of endoscopic gluteus medius repair.
References 1. LaBan MM, Weir SK, Taylor RS. “Bald trochanter” spontaneous rupture of the conjoined tendons of the gluteus medius and minimus presenting as a trochanteric bursitis. Am J Phys Med Rehabil 2004;83:806-809. 2. Bird PA, Oakley SP, Shnier R, Kirkham BW. Prospective evaluation of magnetic resonance imaging and physical examination findings in patients with greater trochanteric pain syndrome. Arthritis Rheum 2001;44:2138-2145. 3. Kingzett-Taylor A, Tirman PF, Feller J, et al. Tendinosis and tears of gluteus medius and minimus muscles as a cause of hip pain: MR imaging findings. Am J Roentgenol 1999;173:1123-1126. 4. Kagan A. Rotator cuff tears of the hip. Clin Orthop 1999;(368):135-140. 5. Thaunat M, Chatellard R, Noël E, Sonnery-Cottet B, Nové-Josserand L. Endoscopic repair of partial-thickness undersurface tears of the gluteus medius tendon. Orthop Traumatol Surg Res 2013;99:853-857. 6. Bunker TD, Esler CN, Leach WJ. Rotator-cuff tear of the hip. J Bone Joint Surg Br 1997;79:618-620. 7. Coulomb R, Essig J, Mares O, Asencio G, Kouyoumdjian P, May O. Clinical results of endoscopic treatment without repair for partial thickness gluteal tears. Orthop Traumatol Surg Res 2016;102:391-395. 8. Bogunovic L, Lee SX, Haro MS, et al. Application of the Goutallier/Fuchs rotator cuff classification to the evaluation of hip abductor tendon tears and the clinical correlation with outcome after repair. Arthroscopy 2015;31: 2145-2151. 9. Engelken F, Wassilew GI, Köhlitz T, et al. Assessment of fatty degeneration of the gluteal muscles in patients with THA using MRI: Reliability and accuracy of the Goutallier and quartile classification systems. J Arthroplasty 2014;29: 149-153. 10. Thaunat M, Noël E, Nové-Josserand L, Murphy CG, Sbiyaa M, Sonnery-Cottet B. Endoscopic management of gluteus medius tendon tears. Sports Med Arthrosc 2016;24:11-18. 11. Lequesne M. From “periarthritis” to hip “rotator cuff” tears. Trochanteric tendinobursitis. Joint Bone Spine 2006;73:344-348.
12. Domb BG, Nasser RM, Botser IB. Partial-thickness tears of the gluteus medius: Rationale and technique for transtendinous endoscopic repair. Arthrosc J 2010;26: 1697-1705. 13. Harris WH. Traumatic arthritis of the hip after dislocation and acetabular fractures: Treatment by mold arthroplasty. An end-result study using a new method of result evaluation. J Bone Joint Surg Am 1969;51:737-755. 14. Christensen CP, Althausen PL, Mittleman MA, Lee J, McCarthy JC. The nonarthritic hip score: Reliable and validated. Clin Orthop 2003;406:75-83. 15. Fuchs B, Weishaupt D, Zanetti M, Hodler J, Gerber C. Fatty degeneration of the muscles of the rotator cuff: Assessment by computed tomography versus magnetic resonance imaging. J Shoulder Elbow Surg 1999;8:599-605. 16. Somerson JS, Hsu JE, Gorbaty JD, Gee JO. Classifications in brief: Goutallier classification of fatty infiltration of the rotator cuff musculature. Clin Orthop Relat Res 2016;474: 1328-1332. 17. Goutallier D, Postel JM, Bernageau J, Lavau L, Voisin MC. Fatty muscle degeneration in cuff ruptures. Pre- and postoperative evaluation by CT scan. Clin Orthop 1994:78-83. 18. Gottschalk F, Kourosh S, Leveau B. The functional anatomy of tensor fasciae latae and gluteus medius and minimus. J Anat 1989;166:179-189. 19. Jaegers S, Dantuma R, de Jongh HJ. Three-dimensional reconstruction of the hip muscles on the basis of magnetic resonance images. Surg Radiol Anat 1992;14:241-249. 20. Cvitanic O, Henzie G, Skezas N, Lyons J, Minter J. MRI diagnosis of tears of the hip abductor tendons (gluteus medius and gluteus minimus). Am J Roentgenol 2004;182: 137-143. 21. Chandrasekaran S, Gui C, Hutchinson MR, Lodhia P, Suarez-Ahedo C, Domb BG. Outcomes of endoscopic gluteus medius repair: Study of thirty-four patients with minimum two-year follow-up. J Bone Joint Surg Am 2015;97:1340-1347. 22. Alpaugh K, Chilelli BJ, Xu S, Martin SD. Outcomes after primary open or endoscopic abductor tendon repair in the hip: A systematic review of the literature. Arthroscopy 2015;31:530-540. 23. Voos JE, Shindle MK, Pruett A, Asnis PD, Kelly BT. Endoscopic repair of gluteus medius tendon tears of the hip. Am J Sports Med 2009;37:743-747. 24. Domb BG, Botser I, Giordano BD. Outcomes of endoscopic gluteus medius repair with minimum 2-year follow-up. Am J Sports Med 2013;41:988-997. 25. Chi AS, Long SS, Zoga AC, et al. Prevalence and pattern of gluteus medius and minimus tendon pathology and muscle atrophy in older individuals using MRI. Skeletal Radiol 2015;44:1727-1733. 26. Collin P, Matsumura N, Lädermann A, Denard PJ, Walch G. Relationship between massive chronic rotator cuff tear pattern and loss of active shoulder range of motion. J Shoulder Elbow Surg 2014;23:1195-1202. 27. Pfirrmann CWA, Notzli HP, Dora C, Hodler J, Zanetti M. Abductor tendons and muscles assessed at MR imaging after total hip arthroplasty in asymptomatic and symptomatic patients. Radiology 2005;235:969-976. 28. Zacharias A, Pizzari T, English DJ, Kapakoulakis T, Green RA. Hip abductor muscle volume in hip
ENDOSCOPIC GLUTEUS MEDIUS REPAIR osteoarthritis and matched controls. Osteoarthritis Cartilage 2016;24:1727-1735. 29. Marcon M, Berger N, Manoliu A, et al. Normative values for volume and fat content of the hip abductor muscles and their dependence on side, age and gender in a healthy population. Skeletal Radiol 2016;45:465-474. 30. Makridis KG, Lequesne M, Bard H, Djian P. Clinical and MRI results in 67 patients operated for gluteus medius
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and minimus tendon tears with a median follow-up of 4.6 years. Orthop Traumatol Surg Res 2014;100:849-853. 31. Delmonico MJ, Harris TB, Visser M, et al. Longitudinal study of muscle strength, quality, and adipose tissue infiltration. Am J Clin Nutr 2009;90:1579-1585. 32. Davies JF, Stiehl JB, Davies JA, Geiger PB. Surgical treatment of hip abductor tendon tears. J Bone Joint Surg Am 2013;95:1420-1425.
Video 1. Surgical technique of endoscopic repair of gluteus medius tendon tear.
Influence of Muscle Fatty Degeneration on Functional Outcomes After Endoscopic Gluteus Medius Repair Mathieu Thaunat, M.D., Gilles Clowez, M.D., Antoine Desseaux, M.D., Colin G. Murphy, M.D., Mouhcine Sbiyaa, M.D., Eric Noël, M.D., and Bertrand Sonnery-Cottet, M.D.
Purpose: To report the early outcomes of endoscopic repair of tears of the gluteus medius tendon and to determine whether the fatty degeneration had an influence on clinical results. Methods: Between October 2012 and June 2014, data were prospectively collected and retrospectively reviewed for all patients who underwent endoscopic gluteus medius repair. Patients were assessed pre- and postoperatively using the modified Harris hip score, the nonarthritic hip score, and visual analog scale for pain. The gluteus minimus and the 3 distinct parts of the gluteus medius (anterior, middle, and posterior) were assigned a grade of fatty degeneration on preoperative magnetic resonance imaging scans. Results: Twenty-two hips (in 20 patients) were assessed with the mean follow-up of 31.7 months (range: 24 to 47 months). There were 15 partial-thickness and 7 full-thickness tears. No patient was lost to follow-up. The mean age at the time of surgery was 66 years (range: 45 to 82 years). Of the 20 magnetic resonance imagingeassessed hips included in the study, 14 had fatty degeneration of the gluteus medius (partial-thickness tears: n ¼ 8, full-thickness tears: n ¼ 6). The mean gluteus medius fatty degeneration index was 1.57 (range: 0.33 to 3.33). Postoperative improvement was seen in modified Harris hip score (33.7 points vs 80.2 points, P ¼ .0001), nonarthritic hip score (47.7 points vs 76.8 points, P ¼ .0001), and in the visual analog scale for pain (7.2 vs 3.2, P < .05). Increasing preoperative fatty degeneration index of the gluteus medius correlated with decreased postoperative functional hip score values (regression coefficient, 0.5839; P < .0001). Tear characteristics (partial or full-thickness) did not correlate with fatty degeneration or muscular atrophy and did not affect postoperative outcomes. Conclusions: Endoscopic surgical repair can be an effective treatment of gluteus medius tears in the short term. Fatty degeneration of the gluteus medius and minimus has a negative impact on clinical outcomes of endoscopic gluteus medius repair. Level of Evidence: Level IV, therapeutic case series (no control group).
G
luteus medius and minimus tendon tears had been recognized as a major cause of recalcitrant greater trochanteric pain syndrome.1-3 Some authors have compared gluteus medius and minimus tendon insertions on the greater trochanter (GT) with those of
From the Ramsay Générale de Santé, Hôpital Privé Jean Mermoz, Centre Orthopédique Santy, Lyon, France. The authors report the following potential conflicts of interest or sources of funding: M.T. and B.S-C. receive consulting fee from Arthrex. G.C. and A.D. had 6-month fellowships sponsored by Arthrex in Centre Orthopédique Santy, Lyon. Full ICMJE author disclosure forms are available for this article online, as supplementary material. Received January 15, 2017; accepted January 2, 2018. Address correspondence to Mathieu Thaunat, M.D., Centre Orthopédique Santy, 24, Avenue Paul Santy, 69008 Lyon, France. E-mail: [email protected] Ó 2018 by the Arthroscopy Association of North America 0749-8063/1736/$36.00 https://doi.org/10.1016/j.arthro.2018.01.005
the rotator cuff on the humerus greater tuberosity, leading to define hip abductor tears as “rotator cuff tears of the hip.”1,4-6 Tears in the gluteus medius and minimus tendons have been recognized as an important cause of recalcitrant greater trochanteric pain syndrome. Because of the frequency of partialthickness undersurface tears, this relatively unknown pathology is often misdiagnosed and left untreated.7 Surgery is indicated in case of 4 associated conditions: (1) duration of symptoms greater than 6 months, (2) magnetic resonance imaging (MRI) showing a tendon tear, (3) positive ultrasound-guided infiltration test, and (4) the absence of either retraction of or an evolved fatty degeneration of the gluteus medius and minimus muscles.5 Goutallier was the first to highlight the link between preoperative muscle fatty degeneration and poor outcomes after rotator cuff repair.3 These findings seem to extend to the repair of the hip abductor muscles.8,9 Endoscopic repair of partial- or full-thickness
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tear resistant to conservative treatment seems to give satisfactory results,10 but to date, only one study has examined the influence of muscular fatty degeneration on the functional results of endoscopic repair of gluteus medius tendon tears.8 The purpose of our study was to report the early outcomes of endoscopic repair of partial- and fullthickness tears of the gluteus medius tendon and to determine whether the fatty degeneration had an influence on clinical results. Our main hypothesis was that endoscopic surgical repair would be an effective treatment of greater trochanteric pain syndrome associated with gluteus medius tears but that fatty degeneration severity of the gluteus minimus and medius affects clinical outcomes.
Methods Patient Selection A retrospective analysis of prospectively collected data was performed of patients who underwent hip endoscopy for greater trochanteric tendinobursitis recalcitrant to medical treatment between October 1, 2012, and June 30, 2014, by one senior surgeon (M.T.). The flow of patients is shown in Figure 1. Continuous series of 22 endoscopic gluteus medius tendon repairs with the same surgical procedure were eligible for evaluation. Inclusion criteria were hip abductor tendon repair and a minimum of 2 years’ follow-up from index surgery. Exclusion criteria were ipsilateral osteoarthritis of the hip and previous hip surgery. Preoperative diagnosis was based on clinical examination, radiograph, and MRI findings. These patients had persistent pain over the GT, symptoms compatible with hip abductors tendinobursitis, such as pain at ipsilateral unipodal weight bearing, and other positive clinical findings described by Lequesne.11 Indications for surgery were chronic pain and disability with clinical and MRI findings compatible with abductor tendon tear associated with failure of 6 months of conservative measures that included anti-inflammatory drugs, physical therapy, and corticosteroid injections. Preoperative MRI showed 7 full-thickness tears and 15 partial tears of hip abductor tendons. Surgical Technique Under a general anesthesia with the patient in the lateral decubitus position, the hip was help in 20 abduction (with pillow bolters). The whole operated limb was included in the surgical field. Three portals were routinely performed (1 distal, 2 proximal), but supplementary portals could be added as required. The iliotibial band was opened in a cruciform fashion 5 cm proximally and distally to the summit of the GT, and the subtrochanteric bursa was then resected. The tendons
Hip endoscopy for recalcitrant GTPS n=25
Endoscopic Gluteus medius repair n=23
Inclusion criteria n=22
Lost to FU n=0
Exclusion criteria n=1
Isolated bursectomy n=2
Fig 1. Patient flow through the study. (FU, follow-up; GTPS, greater trochanteric pain syndrome.)
were inspected and palpated with a palpation hook to identify lesions. The intraoperative tear patterns and the macroscopic appearance of the tendons were recorded. Pathologic tissue was removed using shaver down to the healthy tissue. In case of suspicion of a partial-thickness tear, a transtendinous approach was performed.12 Then the GT was abraded using a motorized burr. All aggressive osteophytes had to be removed and the bald zone of GT’s summit had to be reduced.9 Side-to-side repair was performed using 1 or 2 anchors (U-shaped, with 2 to 4 sutures). In cases of full-thickness tears, double-row repair with suture bridging was used to increase the contact area of the tendon along the anatomic footprint (Fig 2). The iliotibial band was left open at the end of the procedure. No drains were required because blood loss was minimal (Video, available at www.arthroscopyjournal.org). Postoperative Management Rehabilitation was initiated immediately with nonweight-bearing for 6 weeks, avoiding passive lateral rotation, passive adduction, active internal rotation, and active abduction for the first 6 weeks. An abduction brace had to be worn between sessions. Hip motion was extended up to 90 flexion for the first 3 weeks. At 6 weeks, weight bearing was progressively resumed. By 6 months, gait had to be normal and painless. Data Collection Preoperative clinical data were registered at a clinic visit. Visual analog scale for average pain on a numeric scale from 0 to 10 (0 ¼ no pain), 2 functional hip scores, the modified Harris hip score (MHHS),13 the nonarthritic hip score (NAHS),14 body mass index, and the date of early symptoms were collected. Postoperative data added a patient-rated overall satisfaction score (PROS) on a numeric scale from 1 to 10 (10 ¼ extremely satisfied), which enquired if the patient could lie on the operated side and if the patient had forgotten the operated hip. Data were collected at a preoperative clinic visit, 1 year postoperatively, and at the last follow-up either at a clinic visit or by a phone call.
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Fig 2. Arthroscopic view of gluteus medius repair. (A, B) Partial thickness tear of the lateral lamina of the gluteus medius tendon repaired in a side-to-side fashion. (C, D) Speedbridge (Arthrex, Naples, FL) suture repair of a retracted fullthickness tear of the lateral lamina of the gluteus medius tendon. (GMed T, gluteus medius tendon; GT, greater trochanter.)
MRI was systematically performed preoperatively. Transverse, coronal, and sagittal T2-weighted images were used to assess hip abductor tendon type of tear (full- or partial-thickness tear) and trochanteric bursitis. Gluteus minimus and medius fatty degeneration were assessed on the first transverse nonefat-suppressed T1weighted slice below the ipsilateral sacroiliac joint. According to the Goutallier-Fuchs classification,15-17 fatty degeneration was graded for the whole gluteus minimus and for each of the 3 facially distinct parts of the gluteus medius18,19 (Fig 3). Like the Goutallier rotator cuff global fatty degeneration index,17 adding the mean grade value of each part of the muscle determined a gluteus medius fatty degeneration index (GmedFDI). The abductor muscle was deemed atrophic if the size of one or more of its constituent parts size had decreased by at least 25% compared with the contralateral side.20 MRI was performed at 1 year postoperatively to assess tendon healing. Statistical Analysis All data were analyzed with the free collaborative online software EasyMadeStat.com (Easy Made Stat, Neuilly-sur-Seine, France). Variable comparisons were analyzed using the Wilcoxon signed-rank test and Mann-Whitney nonparametric test. The Pearson correlation coefficient was used to find numeric correlation between fatty degeneration of hip abductor muscles and clinical variables. Statistical significance was defined as P < .05.
Results Study Population Between October 2012 and June 2014, 22 hips for 20 patients met the inclusion criteria. Demographic data are summarized in Table 1. The mean follow-up was 31.7 months with a minimum of 24 months (range: 24-47 months). All patients described a progressive onset of symptoms without a history of defined trauma. No patient was lost to follow-up. Clinical Assessment The patients were all reviewed with minimum 2 years’ follow-up and all completed the postoperative questionnaire at a clinic visit or by a phone call. A full set of completed clinical scores and questionnaires (MHHS, NAHS, visual analog scale, PROS) was available for all patients (Table 2). From preoperative to most recent follow-up, there was significant improvement for both hip scores (Fig 4). Patients’ age at surgery, preoperative duration of symptoms, and body mass index did not correlate with pre- and postoperative hip scores (P > .05). Patients reported an overall postoperative satisfaction of 7 (range: 3 to 10). Four operated hips (18%) were reported “forgotten” by the patient. Ten patients (45%) could lie down without pain on the operated side. MRI Assessment Two patients could not pass pre- and postoperative MRI because of the implantation of a pacemaker and were
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Fig 3. Fatty degeneration assessment of the gluteus medius and minimus muscle. (A) Gluteus medius and minimus fatty degeneration were assessed on the first transverse nonefat-suppressed T1-weighted slice below the ipsilateral sacroiliac joint. According to the Goutallier-Fuchs classification, fatty degeneration was graded for all of gluteus minimus and for each of the 3 facially distinct parts of the gluteus medius. Fatty degeneration index (FDI) of the gluteus medius muscle was evaluated adding the mean grade value of each part of the muscle. (B) Normal aspect of the gluteus minimus (GMi), gluteus maximus (GMa), and the 3 distinct parts of the gluteus medius (anterior part [GMeA] circled in blue, middle part [GMeM] circled in yellow, and posterior part [GMeP] circled in red). The FDI is 0.2. (C) Example of a grade 3 fatty degeneration (as much fat as muscle) involving the anterior and the middle part of the gluteus medius muscle. The FDI is 2.7.
Table 1. Epidemiological Factors Patients, n Sex, n Male Female Age (yr), mean SD Height (cm), mean SD Weight (kg), mean SD BMI, mean SD Hips, n Side of surgery, n Left Right Duration of symptoms (yr), mean SD Follow-up (mo), mean SD BMI, body mass index; SD, standard deviation.
20 3 (15%) 17 (85%) 66 8.0 164 6.2 74 13.7 27.6 4.9 22 16 6 3.5 3.2 31.7 7.6
followed with echography. Both were excluded from the MRI data analysis. MRI data were available for 20 hips. Fourteen hips (70%) had fatty degeneration of the gluteus medius. Mean GmedFDI was 1.57 (range: 0.33 Table 2. Clinical Outcomes Parameter MHHS, mean SD NAHS, mean SD VAS, mean SD PROS, mean SD
Preoperative (n ¼ 22) 33.7 8.7 47.7 7.7 7.2 1.0 e
Last Follow-up (n ¼ 22) 80.2 19.4 76.8 14.5 3.2 2.8 7.0 2.3
P Value .0001 .0001 <.05 e
MHHS, modified Harris hip score; NAHS, nonarthritis hip score; PROS, patient-rated overall satisfaction; SD, standard deviation; VAS, visual analog scale.
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Improvements between pre- and postoperative hip score values were significantly higher in the group with either no or one gluteus medius fatty degenerated part when compared with patients with 2 or 3 distinct parts of the gluteus medius muscle affected by fatty degeneration (Fig 6). No differences were noted in the pre- and postoperative scores between the group “no muscular atrophy” and the group “muscular atrophy” (Table 3) or between the group “partial-thickness tear” and the group “full-thickness tear” (Table 4). The small sample size did not allow us to find any correlation between muscular atrophy or fatty degeneration and the completeness of the rupture. Fig 4. Comparison between preoperative and last follow-up functional scores. Values are expressed as mean SD. (MHHS, modified Harris hip score; NAHS, nonarthritic hip score; SD, standard deviation; VAS, visual analog scale.)
to 3.33). Five hips were Goutallier grade 1, 5 were grade 2, 3 were grade 3, and 1 hip was grade 4. Only one of the 3 parts of the gluteus medius was degenerative for 3 hips; 2 parts for 8 hips and the 3 parts of the muscle were degenerative for 3 hips. Preoperative MRI showed gluteus medius muscular atrophy for 6 hips (30%). For these atrophic hips, the mean GmedFDI was 2.22 (range: 0.67 to 3.33) compared with a mean GmedFDI of 1.08 (range: 0.33 to 2.67) for hips without gluteus medius atrophy. For the patients who had fullthickness tears of the gluteus medius, the mean GmedFDI was 1.56 (range: 0 to 3.3) compared with a mean GmedFDI of 0.9 (range: 0 to 1.33) for hips with partial-thickness tears of the gluteus medius (P > .05). Eighteen hips (90%) had fatty degeneration of the gluteus minimus. Two hips were Goutallier grade 1, 8 were grade 2, 6 were grade 3, and 2 were grade 4. The mean gluteus minimus fatty degeneration (GminFD) grade was 2.44. Postoperative MRI results showed 1 failure of partial tendon repair in a female patient, but otherwise 19 of 20 hips showed tendon healing at 1 year. Clinical and MRI Outcome Analysis GmedFDI was strongly negatively correlated with the postoperative MHHS value (R2 ¼ 0.58; P < .0001), NAHS value (R2 ¼ 0.51; P ¼ .0004) (Fig 5), and also with PROS (R2 ¼ 0.57; P < .005). As GmedFDI increased, the values of postoperative MHHS, NAHS, and PROS tended to decrease. GminFD was also negatively correlated with the postoperative MHHS value (R2 ¼ 0.30; P ¼ .0118), NAHS value (R2 ¼ 0.41; P ¼ .0023), and also with PROS (R2 ¼ 0.44; P < .05). As GminFD increased, the values of postoperative MHHS, NAHS, and PROS tended to decrease.
Complications We did not identify any wound problems, infection, or nerve injury. Postoperative MRI results showed 1 failure of tendon repair in a patient.
Discussion The principal findings of our study are that (1) endoscopic gluteus medius tear repair improves overall functional outcomes and patient satisfaction, and (2) functional outcomes and patient satisfaction significantly decrease as preoperative fatty degeneration for both gluteus minimus and medius increases. In 1999, Kagan4 published the first case series with results on open surgical repair of the gluteus medius tendon, noting excellent results at long-term follow-up. Novel endoscopic techniques for the treatment of extraarticular abnormalities of the hip have been reported, including descriptions of endoscopic repair of gluteus medius tears with excellent results and more notably with fewer complications.21-24 However, the fatty degeneration of the gluteus muscle has not been investigated in these studies. Our study shows similar
Fig 5. Correlation between fatty degeneration of the gluteus medius at the time of repair and functional result at the last follow-up. Gluteus medius fatty degeneration index (GmedFDI) was strongly negatively correlated with postoperative modified Harris hip score (MHHS) and nonarthritic hip score (NAHS).
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Fig 6. Patients with no fatty degeneration or 1 fatty degenerated part of the gluteus medius muscle had a significantly higher gain in functional score (MHHS and NAHS) than patients with 2 or 3 fatty degenerated parts of the gluteus medius muscle. (MMHS, modified Harris hip score; NAHS, nonarthritic hip score.)
functional results after endoscopic repair to those previously published. Gluteal muscle atrophy and type of tear (partial-thickness or full-thickness) were also evaluated. Our small sample could not make it possible to highlight a statistical link between full-thickness tears and muscular atrophy or fatty degeneration. Indeed, contrary to the natural evolution of the tendon lesions in the shoulder, these tendons may undergo a gradual process of degeneration with repetitive injury and repair leading to dysfunction and atrophy rather than rupture.25 Some tendons are prone to complete tears, whereas others degenerate with thickening and subsequent fraying, partial-thickness tearing, and thinning with associated muscle atrophy and dysfunction.25 As already described in shoulders,26 our results suggest that there is a correlation between poor clinical results and the extent of fatty degeneration in the different muscle bellies of the gluteus medius muscle.
Although better known for the shoulder, hip abductor muscle fatty degeneration and atrophy are well identified and quantified with MRI.9,25,27-29 Studies with visual fatty degeneration assessment have been mainly reported in the context of patients who were operated for a total hip arthroplasty9,27 or in a context of osteoarthritis28 and usually used several transverse MRI slices. We identified only 2 studies that assessed hip abductor muscle fatty degeneration before surgical repair of the gluteus medius tendon.8,30 Makridis et al.30 reported 20% of patients with hip abductor muscle fatty degeneration in a cohort of 67 patients who underwent an open double-row tendon repair. Muscle atrophy was a predictor of bad prognosis in their study. However, no significant changes in the postoperative clinical outcomes were reported between patients with hip abductor fatty degeneration and patients without.30 Bogunovic et al.8 previously reported
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ENDOSCOPIC GLUTEUS MEDIUS REPAIR Table 3. Pre- and Postoperative Hip Score Values Depending on Gluteus Medius Trophicity
GmedFDI, mean SD MHHS Preop., mean SD Postop., mean SD P value NAHS Preop., mean SD Postop., mean SD P value
Atrophic, n¼6 2.22 0.9
Nonatrophic, n ¼ 14 0.62 0.8
33.3 10.5 70.2 20.7 <.05
34.6 8.7 82.7 18.8 <.05
>.05 >.05
45.8 10.3 69.8 12.3 <.05
48.9 7.1 79.3 15.7 <.05
>.05 >.05
P Value <.01
GmedFDI, gluteus medius fatty degeneration index; MHHS, modified Harris hip score; NAHS, nonarthritis hip score; SD, standard deviation.
similar results to ours after endoscopic repair of the gluteus tendon, finding that an increase in preoperative hip abductor muscle fatty degeneration is correlated with poor outcomes; however, they reported an 80% rate of associated intra-articular procedures such as labral debridement, repair, and cam/pincer decompression. In this latter study, the fatty degeneration of the gluteus medius muscle was assessed on a unique coronal slice. We believe that only transverse T1 slice allows a good complete anterior-posterior analysis of the 3 anatomical parts of the gluteus medius well described by Gottschalk et al.18 It allows analyzing fatty degeneration not only in terms of severity according to the Goutallier-Fuchs classification but also in terms of extension to the entire muscle, which, we believe, has never been proposed. Studies highlight that it is common to observe a slight fatty degeneration of all gluteal muscles even in a healthy population, but rarely more than low grades and mostly corresponding to Goutallier grade 1.9,28,29 Engelken et al.9 reported minor fatty degeneration of the gluteus minimus, equivalent to Goutallier grade 1 in their asymptomatic control group; however, in this study, the mean age of the control group was 31.2 years compared with 64.9 years for the symptomatic group. Marcon et al.29 also found no age dependence in hip abductor fatty degeneration in healthy volunteers. Other studies report opposite results with muscle fatty degeneration increasing with age.25,31 Because the natural history of these lesions is different from those observed in the shoulder (frequency of partial thickness lesions at the time of repair), it seems important to define the thresholds in terms of age and fatty degeneration (extension and severity) constituting a contraindication for tendon repair and when a limited endoscopic bursectomy should be proposed instead. Although endoscopic gluteus medius repair seems to show good preliminary outcomes, similarly effective to open repair and with less complication rates,21-24,30,32
many of our patients have reported less optimistic outcomes and one patient in our series had a failure of tendon healing on postoperative MRI. The rate of tendon retear after open repair was between 9% and 11% in studies with a large sample size and a longer follow-up,22 and the lower rate reported in endoscopic studies is probably linked to the small sample and short follow-up. Several studies have noted the degenerative condition of the gluteal tendons at the time of repair, and this may be a predisposing factor for retears.22 The degree of tendon degeneration may compromise the tissue left for reattachment, raising concerns over its healing capacity, durability, and ultimate strength. Hence, we believe that the GT abrasion is an essential step and could be compared with the acromioplasty performed during a rotator cuff repair in the shoulder. A cortical bone abrasion should be carried out with the high-speed burr until bleeding cancellous bone is present not only to stimulate a biologic response but also to remove all aggressive osteophytes. The bald zone of summit of the GT must be reduced, as most lesions are located on the deep side of the lateral lamina of the gluteus medius: presumably, the GT aggresses the tendon and is implicated in these partial-thickness lesions by a “wiper” effect during rotation.5,10 Limitations The retrospective nature, the absence of comparative group, the small sample size, and the short follow-up of this study are its main limitations. However, the low number of patients in our series makes the analysis of the gluteus medius fatty degeneration extent in subgroups at risk of statistical error. Thus, subgroups are so small that it is possible that a different result in as few as one additional patient could change the conclusion. Furthermore, and perhaps as a result of the small groups, although we do show statistical differences, the overlapping confidence intervals suggest no clinical differences between groups. However, current studies devoted to endoscopic repair of the gluteal muscle also Table 4. Pre- and Postoperative Hip Score Values Depending on the Type of Hip Abductor Tear
GmedFDI, mean SD MHHS Preop., mean SD Postop., mean SD P value NAHS Preop., mean SD Postop., mean SD P value
Full-thickness Tear, n ¼ 6 1.56 1.3
Partial-thickness Tear, n ¼ 14 0.9 0.9
35.9 7.4 74.3 20.4 <.05
32.7 9.4 83.0 18.8 <.05
>.05 >.05
48.5 7.5 71.6 11.4 <.05
47.3 8.0 79.2 15.4 <.05
>.05 >.05
P Value >.05
GmedFDI, gluteus medius fatty degeneration index; MHHS, modified Harris hip score; NAHS, nonarthritis hip score; SD, standard deviation.
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have low numbers of patients. In addition, greater trochanteric pain syndrome and gluteal tendon tears may be more symptomatic or more prevalent in women, but the uneven gender distribution in this study does limit the generalizability of the results. We report only one case of tendon repair failure but given that several patients reported poorer outcomes scores, it is possible that other retears occurred later without MRI proof.
Conclusions This study suggests that endoscopic surgical repair can be an effective treatment of gluteus medius tears in the short term. Fatty degeneration of the gluteus medius and minimus has a negative impact on clinical outcomes of endoscopic gluteus medius repair.
References 1. LaBan MM, Weir SK, Taylor RS. “Bald trochanter” spontaneous rupture of the conjoined tendons of the gluteus medius and minimus presenting as a trochanteric bursitis. Am J Phys Med Rehabil 2004;83:806-809. 2. Bird PA, Oakley SP, Shnier R, Kirkham BW. Prospective evaluation of magnetic resonance imaging and physical examination findings in patients with greater trochanteric pain syndrome. Arthritis Rheum 2001;44:2138-2145. 3. Kingzett-Taylor A, Tirman PF, Feller J, et al. Tendinosis and tears of gluteus medius and minimus muscles as a cause of hip pain: MR imaging findings. Am J Roentgenol 1999;173:1123-1126. 4. Kagan A. Rotator cuff tears of the hip. Clin Orthop 1999;(368):135-140. 5. Thaunat M, Chatellard R, Noël E, Sonnery-Cottet B, Nové-Josserand L. Endoscopic repair of partial-thickness undersurface tears of the gluteus medius tendon. Orthop Traumatol Surg Res 2013;99:853-857. 6. Bunker TD, Esler CN, Leach WJ. Rotator-cuff tear of the hip. J Bone Joint Surg Br 1997;79:618-620. 7. Coulomb R, Essig J, Mares O, Asencio G, Kouyoumdjian P, May O. Clinical results of endoscopic treatment without repair for partial thickness gluteal tears. Orthop Traumatol Surg Res 2016;102:391-395. 8. Bogunovic L, Lee SX, Haro MS, et al. Application of the Goutallier/Fuchs rotator cuff classification to the evaluation of hip abductor tendon tears and the clinical correlation with outcome after repair. Arthroscopy 2015;31: 2145-2151. 9. Engelken F, Wassilew GI, Köhlitz T, et al. Assessment of fatty degeneration of the gluteal muscles in patients with THA using MRI: Reliability and accuracy of the Goutallier and quartile classification systems. J Arthroplasty 2014;29: 149-153. 10. Thaunat M, Noël E, Nové-Josserand L, Murphy CG, Sbiyaa M, Sonnery-Cottet B. Endoscopic management of gluteus medius tendon tears. Sports Med Arthrosc 2016;24:11-18. 11. Lequesne M. From “periarthritis” to hip “rotator cuff” tears. Trochanteric tendinobursitis. Joint Bone Spine 2006;73:344-348.
12. Domb BG, Nasser RM, Botser IB. Partial-thickness tears of the gluteus medius: Rationale and technique for transtendinous endoscopic repair. Arthrosc J 2010;26: 1697-1705. 13. Harris WH. Traumatic arthritis of the hip after dislocation and acetabular fractures: Treatment by mold arthroplasty. An end-result study using a new method of result evaluation. J Bone Joint Surg Am 1969;51:737-755. 14. Christensen CP, Althausen PL, Mittleman MA, Lee J, McCarthy JC. The nonarthritic hip score: Reliable and validated. Clin Orthop 2003;406:75-83. 15. Fuchs B, Weishaupt D, Zanetti M, Hodler J, Gerber C. Fatty degeneration of the muscles of the rotator cuff: Assessment by computed tomography versus magnetic resonance imaging. J Shoulder Elbow Surg 1999;8:599-605. 16. Somerson JS, Hsu JE, Gorbaty JD, Gee JO. Classifications in brief: Goutallier classification of fatty infiltration of the rotator cuff musculature. Clin Orthop Relat Res 2016;474: 1328-1332. 17. Goutallier D, Postel JM, Bernageau J, Lavau L, Voisin MC. Fatty muscle degeneration in cuff ruptures. Pre- and postoperative evaluation by CT scan. Clin Orthop 1994:78-83. 18. Gottschalk F, Kourosh S, Leveau B. The functional anatomy of tensor fasciae latae and gluteus medius and minimus. J Anat 1989;166:179-189. 19. Jaegers S, Dantuma R, de Jongh HJ. Three-dimensional reconstruction of the hip muscles on the basis of magnetic resonance images. Surg Radiol Anat 1992;14:241-249. 20. Cvitanic O, Henzie G, Skezas N, Lyons J, Minter J. MRI diagnosis of tears of the hip abductor tendons (gluteus medius and gluteus minimus). Am J Roentgenol 2004;182: 137-143. 21. Chandrasekaran S, Gui C, Hutchinson MR, Lodhia P, Suarez-Ahedo C, Domb BG. Outcomes of endoscopic gluteus medius repair: Study of thirty-four patients with minimum two-year follow-up. J Bone Joint Surg Am 2015;97:1340-1347. 22. Alpaugh K, Chilelli BJ, Xu S, Martin SD. Outcomes after primary open or endoscopic abductor tendon repair in the hip: A systematic review of the literature. Arthroscopy 2015;31:530-540. 23. Voos JE, Shindle MK, Pruett A, Asnis PD, Kelly BT. Endoscopic repair of gluteus medius tendon tears of the hip. Am J Sports Med 2009;37:743-747. 24. Domb BG, Botser I, Giordano BD. Outcomes of endoscopic gluteus medius repair with minimum 2-year follow-up. Am J Sports Med 2013;41:988-997. 25. Chi AS, Long SS, Zoga AC, et al. Prevalence and pattern of gluteus medius and minimus tendon pathology and muscle atrophy in older individuals using MRI. Skeletal Radiol 2015;44:1727-1733. 26. Collin P, Matsumura N, Lädermann A, Denard PJ, Walch G. Relationship between massive chronic rotator cuff tear pattern and loss of active shoulder range of motion. J Shoulder Elbow Surg 2014;23:1195-1202. 27. Pfirrmann CWA, Notzli HP, Dora C, Hodler J, Zanetti M. Abductor tendons and muscles assessed at MR imaging after total hip arthroplasty in asymptomatic and symptomatic patients. Radiology 2005;235:969-976. 28. Zacharias A, Pizzari T, English DJ, Kapakoulakis T, Green RA. Hip abductor muscle volume in hip
ENDOSCOPIC GLUTEUS MEDIUS REPAIR osteoarthritis and matched controls. Osteoarthritis Cartilage 2016;24:1727-1735. 29. Marcon M, Berger N, Manoliu A, et al. Normative values for volume and fat content of the hip abductor muscles and their dependence on side, age and gender in a healthy population. Skeletal Radiol 2016;45:465-474. 30. Makridis KG, Lequesne M, Bard H, Djian P. Clinical and MRI results in 67 patients operated for gluteus medius
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and minimus tendon tears with a median follow-up of 4.6 years. Orthop Traumatol Surg Res 2014;100:849-853. 31. Delmonico MJ, Harris TB, Visser M, et al. Longitudinal study of muscle strength, quality, and adipose tissue infiltration. Am J Clin Nutr 2009;90:1579-1585. 32. Davies JF, Stiehl JB, Davies JA, Geiger PB. Surgical treatment of hip abductor tendon tears. J Bone Joint Surg Am 2013;95:1420-1425.
Video 1. Surgical technique of endoscopic repair of gluteus medius tendon tear.