How to activate the glutes best? Peak muscle activity of acceleration-specific pre-activation and traditional strength training exercises.

PURPOSE: Isometric training and pre-activation are proven to enhance acceleration performance. However, traditional strength training exercises do not mirror the acceleration-specific activation patterns of the gluteal muscles, characterized by ipsilateral hip extension during contralateral hip flexion. Therefore, the aim of the study was to determine gluteal muscle activity of acceleration-specific exercises compared to traditional strength training exercises. METHODS: In a cross-sectional study design, the peak electromyographic activity of two acceleration-specific exercises was investigated and compared to two traditional strength training exercises each for the gluteus maximus and medius. Twenty-four participants from various athletic backgrounds (13 males, 11 females, 26 years, 178 cm, 77 kg) performed four gluteus maximus [half-kneeling glute squeeze (HKGS), resisted knee split (RKS), hip thrust (HT), split squat (SS)] and four gluteus medius [resisted prone hip abduction (RPHA), isometric clam (IC), side-plank with leg abduction (SP), resisted side-stepping (RSS)] exercises in a randomized order. RESULTS: The RKS (p = 0.011, d = 0.96) and the HKGS (p = 0.064, d = 0.68) elicited higher peak gluteus maximus activity than the SS with large and moderate effects, respectively. No significant differences (p > 0.05) were found between the HT, RKS and HKGS. The RPHA elicited significantly higher gluteus medius activity with a large effect compared to RSS (p < 0.001, d = 1.41) and a moderate effect relative to the SP (p = 0.002, d = 0.78). CONCLUSION: The acceleration-specific exercises effectively activate the gluteal muscles for pre-activation and strength training purposes and might help improve horizontal acceleration due to their direct coordinative transfer.

Does Focused Gluteus Medius Muscle Stretching After Total Hip Arthroplasty Work? An Electromyographic Study.

BACKGROUND: The hypothesis of this randomized prospective study was that focused stretching of the gluteus medius muscle, in addition to generalized physical therapy, is likely to improve muscle reaction time and positively impact the return to function of the patient after primary total hip arthroplasty. METHODS: We prospectively recruited 28 patients undergoing primary total hip arthroplasty from January 2021 to January 2023. The control group (13 patients) received a conventional rehabilitation protocol, while the intervention group (15 patients) received focused stretching exercises of the gluteus medius muscle in addition to the conventional rehabilitation protocol. Patients had preoperative and postoperative surface electromyography (sEMG) to assess muscle activity. RESULTS: Patients in the intervention group after surgery had better muscle activation according to sEMG during walking and during one leg stance compared to the control group. Also, patients from the intervention group had better strength of the gluteus medius muscle after surgery, but this did not reach statistical significance. CONCLUSIONS: The present prospective study demonstrated that implementation of focused gluteus medius muscle stretching results in statistically significantly higher muscle activation as measured by sEMG. The strength of the gluteus medius muscle is also higher as measured using a dynamometer, albeit not reaching statistical significance. Based on the findings of this sEMG study, it appears that focused stretching and strengthening of abductors muscles are beneficial.

Gluteus Maximus Transfer for Irreparable Hip Abductor Deficiency: A Systematic Review and Meta-Analysis.

BACKGROUND: Gluteus maximus tendon transfer has recently been described as a treatment option for irreparable abductor tendon tears. The purpose of this study was to systematically review outcomes following gluteus maximus tendon transfer for hip abductor deficiency. METHODS: The published literature was queried for outcomes following gluteus maximus transfer in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Outcomes of interest included preoperative and postoperative functional scores, resolution of pain and gait abnormalities, postoperative rehabilitation protocols, surgical complications, reoperation rates, and postoperative magnetic resonance imaging. In total, 10 studies with a total of 125 patients (76% women) with a mean age of 67 years (range, 30 to 87) were identified for inclusion. RESULTS: Modified Harris Hip Score (+30.1 ± 6.6 [95% confidence interval: +15.5 to +46.5]) and Visual Analog Scale for pain (-4.1 ± 1.1 [95% confidence interval: -7.1 to -1.0]) were improved following gluteus maximus transfer, compared to preoperative levels. No significant improvement was noted in abduction strength and 33% of patients demonstrated a residual Trendelenburg gait postoperatively. The overall complication rate was 5.6% (7 of 125), with a reoperation rate of 1.6% (2 of 125). CONCLUSIONS: Gluteus maximus tendon transfer for abductor insufficiency has demonstrated reliable outcomes at 3 years, with improvement in hip function and pain. However, patients demonstrate modest improvements in abduction strength, and a significant subset will continue to demonstrate a Trendelenburg gait postoperatively.

Changes in the Activity of the Erector Spinae and Gluteus Medius Muscles with the Presence of Simulated Lower Limb Dysmetria.

(1) Background: Leg length discrepancy (LLD), regardless of its origin, is a very common pathology that can contribute to low back pain. Various authors have pointed out its relationship with the lack of activation of both the gluteus medius (GM) and the ipsilateral erector spinae (ES). The purpose of this study was to identify the activation of the ES and GM with different simulated LLDs, correlating this activation with LBP. In turn, we evaluated whether ES and GM activity has an effect on jumping ability using a CMJ test. (2) Method: A sample of healthy subjects was selected to whom an artificial LLD was applied using 0.5, 1, and 1.5 cm insoles. These three heights were measured using EMG while the subjects walked and performed a counter movement jump (CMJ). The measurements of the insole heights were carried out in random order using a Latin square. Muscle activation patterns were recorded for 30 s at each of the insole heights while the patients walked at 5.7 km/h and they were compared with the maximum voluntary contraction (MVC), both on the ipsilateral and contralateral sides. These muscles were then measured under the same circumstances during the performance of the CMJ. (3) Results: We found statistically significant differences in the flight heights in both the CMJ and DJ. In the comparison, significant differences were found in the flight heights of the CMJ and the DJ using the 5 mm insoles, and in the case of the DJ, also without insoles, with respect to the MVC. We found statistically significant differences in the activation of the GM with the differences in insoles, but not in the activation of the Es in relation to the different insole heights. (4) Conclusions: Insoles of different heights caused activation differences in the medius on the side where the insoles were placed. We can relate this difference in activation to LBP. In relation to the ES, no significant differences were found in the activation of the ipsilateral side of the insole.

Reduced Cross-Sectional Area of the Gluteus Medius Muscle is Associated With Decreased Activities of Daily Living in Older Adult Patients With Hip Fractures.

We investigated the association between the cross-sectional area (CSA) of the gluteus medius muscle (GMM) and activities of daily living in patients with hip fractures. This retrospective cohort study comprised 111 patients aged ≥65 years who underwent hip fracture rehabilitation. The CSA of the GMM was measured using computed tomography scans in the early stages of hospitalization. The group with decreased CSA of the GMM had a median GMI ≤17 cm2/m2 for male patients and ≤16 cm2/m2 for female patients. Patients in the group with decreased CSA of the GMM had lower functional independence measure gains than those in the control group. After adjusting for confounders, we found that decreased CSA of the GMM was significantly associated with lower functional independence measure gains (ß: -0.432, p < .001). In patients with hip fractures, decreased CSA of the GMM was associated with decreased activities of daily living.

Short-term functional outcomes of Whiteside transfer for massive rupture of gluteus medius tendon in native hips.

PURPOSE: To assess the functional and clinical outcomes of patients who underwent either open or endoscopic Whiteside transfer of gluteus maximus and tensor fascia lata muscles in cases of massive rupture of gluteus medius tendon associated with muscle atrophy on a native hip METHODS: This retrospective, descriptive, single-centre study was conducted by a single operator with a minimum follow-up period of 12 months. All Whiteside palliative transfers performed on patients with Type 5 gluteus medius tendon rupture, according to Lall's classification, resulting in painful and treatment-resistant Trendeleburg gait between 2017 and 2022 were included. Functional evaluation was based on modified Harris Hip Scores (mHHS), iHOT-12, Non-Arthritic Hip Score (NAHS), and the pain on a Visual Analog Scale (VAS). Muscle strength was clinically assessed using the MRC classification. RESULTS: Between January 2017 and January 2022, a total of 15 Whiteside palliative transfers were identified, including nine (60%) open procedures and 6 (40%) endoscopic procedures, performed on 13 patients. One patient was excluded, and none were lost to follow-up. The median follow-up period was 41 (12; 59) months. The median age at the time of surgery was 74 (66; 76) years. The male-to-female sex ratio was 0.27. Functional results demonstrated a significant improvement in all scores: NAHS (45 vs. 72, p = 0.002), mHHS (22 vs. 55, p = 0.002), iHOT-12 (101 vs. 56, p = 0.002), and VAS (8 vs. 3, p = 0.002). Clinical outcomes also showed improvements in muscle strength (p = 0.003), single-leg stance (p = 0.01), and gait (p = 0.02). No significant differences were found in the various scores between the endoscopic and open techniques. CONCLUSION: Whiteside transfer surgery, whether performed through open surgery or endoscopically, is a palliative surgical approach that should be considered for patients with irreparable gluteus medius tendon tears, where the main symptom is trochanteric pain. This procedure yields satisfactory clinical and functional outcomes, although the gains in abduction strength recovery and gait improvement are modest.

Satisfactory results after endoscopic gluteus medius repair combined with selective gluteus maximus reflected tendon release for the treatment of a full-thickness tear of gluteus medius.

PURPOSE: The current study aimed to report the mid-term follow-up results of endoscopic gluteus medius repair combined with a systematic release of the gluteus maximus reflected tendon. METHODS: Twenty-two patients with a symptomatic full-thickness tear of the gluteus medius tendon, as diagnosed by clinical examination and imaging (MRI), and who had a failure of conservative treatment for at least 6 months, were retrospectively enrolled for this study. An endoscopic repair of gluteus medius was performed for all patients in combination with gluteus maximus reflected tendon release according to the Polesello technique. The Visual Analogue Scale (VAS) for pain, Modified Harris Hip Score (mHHS), Lower Extremity Functional Scale (LEFS), Hip Outcome Score-Activity Daily Life (HOS-ADL), and Hip Outcome Score-Sport Specific Subscale (HOS-SSS) were administered to each patient before surgery for 6 months, 1 year, and every following year after surgery. RESULTS: All analysed hip scores (mHHS, LEFS, HOS-ADL, and HOS-SSS) showed statistically significant improvements between the pre-operative and post-operative values at 6 months, 1 year, and the latest follow-up appointments after surgery (p < 0.001). The mean pre-operative pain was 8.6 ± 1.0 on the VAS. After surgical treatment, the pain was significantly reduced (p < 0.001) on the VAS at 6 months (5.4 ± 1.5), 1 year (4.4 ± 1.8) and the latest follow-up control visit (3.6 ± 2.2). No patient-reported major complications (re-rupture, deep infection or neurovascular injury). Eleven (50%) patients indicated the results as excellent, 7 (32%) as good, 2 (9%) as fair, and 2 (9%) as poor. CONCLUSION: The use of abductor tendon repair in combination with a systematic release of the reflected tendon of the gluteus maximus according to the Polesello technique seems to be a safe and effective endoscopic way of treating a full-thickness tear of the gluteus medius. LEVEL OF EVIDENCE: Level IV.

Assessment of the Damage to Hip Abductor Muscles in Primary Total Hip Arthroplasty With a Minimally Invasive Anterolateral Approach With or Without Trochanteric Flip Osteotomy.

BACKGROUND: Although introduction of minimally invasive techniques via anterolateral approaches considerably decreased prolonged limp after total hip arthroplasty (THA), potential damage to the abductor muscles is still a concern. This study aimed to evaluate the residual damage after primary THA with two types of anterolateral approach by assessing fatty infiltration and atrophy of the gluteus medius (GMed) and gluteus minimus (GMin) muscles. METHODS: We retrospectively analyzed 100 primary THAs using computed tomography; surgeries were performed by detaching the anterior part of the abductor muscles with a bone fragment (anterolateral approach with trochanteric flip osteotomy) or without it (anterolateral approach without trochanteric flip osteotomy). The change in radiodensities (RDs), cross-sectional areas (CSAs), and clinical scores preoperatively and at 1 year after operation were evaluated. RESULTS: The RD and CSA of GMed increased 1 year postoperatively in 86 and 81% of patients, respectively, while RD and CSA of GMin decreased in 71 and 94%, respectively. The improvement of RD of GMed was more frequently seen in the posterior rather than the anterior part, while the GMin decreased in both parts. The RD decrease of GMin was significantly lower in the anterolateral approach with trochanteric flip osteotomy group than the anterolateral approach without trochanteric flip osteotomy group (P = .0250). However, there was no difference in the clinical scores between the two groups. The change in the RD of GMed was the only factor that correlated with clinical scores. CONCLUSION: The two anterolateral approaches both improved the RD of GMed, recovery of which was significantly associated with postoperative clinical scores. Although the two approaches showed different recovery patterns in GMin until 1 year after THA, both showed similar improvements in clinical scores.

Examination of hip function and muscle activity during clam exercise.

[Purpose] Clam exercise is commonly used to strengthen hip abductor muscles. This study aimed to classify the directions of greater trochanter movement during clam exercise and examine whether this classification reveals any differences in the characteristics of muscle activities. [Participants and Methods] Twenty healthy male participants were included and were divided into three groups according to the direction of greater trochanter movements during clam exercise: diagonally upward, backward, and upward. Muscle activity of the gluteus medius, gluteus maximus, tensor fascia lata, and external oblique was measured during clam exercise, along with the direction of greater trochanter movement and maximum muscle strength in the clam exercise limb position. [Results] In the diagonally upward group, the gluteus medius muscles showed higher activity than the other three muscles, and their activity was higher in the diagonally upward and backward groups than in the upward group. [Conclusion] The tension and action vector of the muscles changed due to differences in the direction of the greater trochanter movement caused by the movement pattern of each participant. The muscle activity around the hip joint changes with the direction of greater trochanter movement during clam exercise.

Hip medial rotator action of gluteus medius in Japanese macaque (Macaca fuscata) and implications to adaptive significance for quadrupedal walking in primates.

The gluteus medius (GM) muscle in quadrupedal primates has long been thought to mainly act as a hip extensor. However, previous reports argue that it may be a prime hip medial rotator and functions to rotate the pelvis in the horizontal plane, suggesting the functional differentiation between the GM and other hip extensors as hamstrings. In this study, we aim to quantify the muscle actions of the GM and hamstrings using muscle moment arm lengths and discuss the functional differentiation among hip extensors. Muscle attachment sites of eight specimens of Japanese macaque (Macaca fuscata) were digitized, and musculoskeletal models were constructed. Flexor-extensor, abductor-adductor, and medial-lateral rotator moment arms were calculated as the models were moved following the experimentally acquired kinematic data during walking on a pole substrate. Using electromyography, we also recorded the pattern of muscle activation. The GM showed a larger medial rotator moment arm length than the extensor moment arm length when it was activated, suggesting this muscle acts mainly as a hip medial rotator rather than as a hip extensor. The medial rotator action of the GM in the early support phase may rotate the pelvis in the horizontal plane and function to help contralateral forelimb reaching as a previous study suggested and facilitate contralateral hindlimb swinging to place the foot near the ipsilateral forelimb's hand.

Hip Gluteus Medius Tears Are Associated With Lower Femoral Neck-Shaft Angles and Higher Acetabular Center-Edge Angles.

PURPOSE: 1) To assess the possible relationship between the morphology of femur or acetabulum and the gluteus medius pathology. 2) To analyze the outcome of isolated arthroscopic treatment of femoroacetabular impingement (FAI) for patients with radiographic gluteus medius tear. METHODS: We performed a retrospective study of FAI patients who underwent arthroscopy between January 2016 to December 2019. Demographic data, such as sex, age, body mass index (BMI), symptom duration, were collected. Radiographic parameters, including alpha angle, lateral center-edge angle (LCEa), femur neck-shaft angle (NSa), gluteus medius pathology, were also collected. Exclusion criteria were previous hip conditions, such as osteoarthritis (Tönnis grade > 1), rheumatoid arthritis, ankylosing spondylitis, snapping hip, previous surgery on the ipsilateral hip, or incomplete data. We followed up these patients with radiographic gluteus medius tear. No surgical procedure for gluteus medius was performed. The minimum follow-up period was 13 months. Patient-reported outcomes, such as modified Harris Hip score (mHHS), visual analog scale (VAS), and patient acceptable symptom state (PASS), as well as physical examination data, including tenderness at the greater trochanter, abductor weakness, limping gait, and positive Trendelenburg sign or test, were gathered preoperatively and postoperatively. RESULTS: A total of 569 hips (314, 55.2% male) were collected eventually, with a mean age of 36.5 ± 10.4 years (range: 13.0 to ∼65.0). Gluteus medius pathology was found in 209 (36.7%) hips, including 41 (7.2%) partial-thickness tears and 10 (1.8%) complete tears. The NSa of the normal, tendinosis, partial tear, and complete tear groups was 133.8 ± 4.7°, 130.6 ± 3.8°, 129.4 ± 3.9°, and 129.6 ± 3.4°, respectively (P < .001). The LCEa of each group was 31.7 ± 35.7°, 33.3 ± 6.5°, 34.9 ± 6.8°, and 33.7 ± 8.1°, respectively (P = .004). On multivariable logistic regression analysis, lower NSa and higher LCEa were identified as risk factors for developing gluteus medius pathology (P < .001). For patients with gluteus medius tear, two cases were lost to follow-up and two cases had incomplete data. The mean follow-up period of the remaining 47 hips was 29.5 ± 12.9 (range: 13 to 59) months. The mHHS improved from 54.8 ± 19.1 to 90.1 ± 6.7 points (P < .001), and VAS decreased from 6.8 ± 1.6 to 3.0 ± 1.6 points (P < .001). Forty-two cases met the threshold of PASS, with a rate of 89%. The abductor strength increased from 4.1 ± 1.00 to 4.6 ± .7 grades (P = .002). However, for patients with a completely torn gluteus medius, improvement of abductor strength was not significant statistically (3.4 ± .9 to 3.9 ± .9, P = .234). CONCLUSION: There was a correlation between lower NSa/higher LCEa and gluteus medius pathology. Isolated arthroscopic treatment of FAI for patients with radiographic gluteus medius tear can gain satisfactory patient-reported outcomes. LEVEL OF EVIDENCE: Therapeutic case series, IV.

Clinical Outcomes for Open Hip Abductor Repair Using Tenodesis and Bone Trough Repair Techniques.

BACKGROUND: Hip abductor complex tears remain an injury without a clear consensus on management. Surgical treatment has been recommended after unsuccessful nonoperative management. This study evaluates both tenodesis and bone trough techniques, with treatment choices guided by previously described tear classification. METHODS: This is a retrospective cohort study of 45 hips in 44 patients who underwent surgical treatment for symptomatic, chronic hip abductor tear unresponsive to nonoperative treatment. Demographics and preoperative and postoperative values (including visual analog scale pain scores, gait assessment, and muscle strength) were evaluated. Type I tears were treated using tendon tenodesis. Type II tears were treated through a bone trough repair. RESULTS: Forty-five hips (44 patients) were operated on with a minimum of 6-month follow-up. There were 27 type I and 18 type II tears. Eighty-seven percent of patients were female. Twenty-eight percent of type II patients (5/18) had a preexisting arthroplasty in place. Significant improvements in pain (P < .001), gait (P < .001), and muscle strength (P < .001) were achieved in both the tear types. Type I repairs showed superior results to type II repairs. However, both showed significant improvements. Postoperative magnetic resonance imaging at 6 months showed healed tenodesis in 81% (17/21) of type I tears and 50% (5/10) of type II tears. CONCLUSION: Our study shows improvement in pain and function after surgical repair of hip abductor tendon injuries in both simple and complex tears. This improvement is seen even during ongoing surgical site healing. Magnetic resonance imaging findings may remain abnormal for more than 1 year after surgery and do not clearly denote repair failure.

What happens to the gluteus medius in young and middle-aged patients with hip dysplasia?

BACKGROUND: Much research has focused on quantifying the bony characteristics of patients with developmental dysplasia of the hip (DDH). Far less attention, however, has been paid to muscle abnormalities around the hip such as those in the gluteus medius (GM). METHODS: We retrospectively examined clinical and imaging data, such as the age of onset and computed tomography (CT) findings, in 108 consecutive hips. Subjects for the control group were selected from our radiology database. Two readers independently evaluated the length (LGM), cross-sectional area (CSA), width (WGM), and thickness (TGM) of the GM and arm of GM (AGM) and angle of the GM activation (AOA) and bony parameters including the acetabulum-head index (AHI), lateral central edge angle (LCEA), acetabular index (AI), femoral offset (FO), and height of the rotation centre of femoral head (HCFH) among all cases using the imaging data. RESULTS: The patient group included 108 hips. The AGM, LGM, CSA, and TGM were lower in the DDH patients, while AOA was higher. However, there was no significant difference in the WGM between the two groups. Multiple linear regression analysis showed that AGM and AOA were independent factors affecting LCEA. The following regression equation was used: Y(LCEA) = 5.377 * X1 (AGM) - 0.310 * X2 (AOA) - 11.331. The mechanical characteristics of the GM and many bony parameters were significantly correlated (the AGM and AHI, LCEA, AI, FO, but not HCFH; AOA and AHI, LCEA, AI, but not FO or HCFH). The CSA was positively correlated with only HCFH. The rest were not statistical significance linear correlation. The multivariate regression results showed that the age of onset was positively correlated with AGM (r = 0.467). The regression equation used was Y = 9.0 * X (age of onset) - 11.4. CONCLUSION: We found difference in the morphological and mechanical characteristics of the GM between hips with DDH and hips of normal morphology. Of note, the mechanical characteristics of the GM were influenced by bony parameters in patients with DDH.

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.

A macroscopic anatomical study of the appropriate palpation zone of the gluteus medius muscle.

[Purpose] Few previous studies have delimitated the palpation zone of the gluteus medius muscle with a focus on its fiber bundles. The purpose of this study was to clarify the morphological characteristics of the gluteus medius muscle using an anatomical approach, and to define its proper palpation zone. [Participants and Methods] In this study, we evaluated thirteen halves of the pelvic region in seven formalin-fixed cadavers. We identified the borders between the iliotibial band and gluteus medius muscle, and between the gluteus medius and gluteus maximus muscles, on the iliac crest. Furthermore, we quantified the border points of the gluteus medius' fiber bundles and observed its anatomical and morphological characteristics. [Results] We identified two fiber bundles in the gluteus medius muscle, an anterior and a posterior fiber bundle, and detected that a portion of the posterior fibers was located subcutaneously. [Conclusion] We propose that the region where the posterior fibers of the gluteus medius muscle are located subcutaneously is an appropriate zone for the palpation of this muscle.

A roadmap to develop clinical guidelines for open surgery of acute and chronic tears of hip abductor tendons.

PURPOSE: Abductor tendon tears are increasingly recognised as a common cause of lateral hip pain. Surgical treatment of these tears has been recommended, but the indications and types of open surgery have not been precisely elucidated yet. This manuscript aimed to critically review the literature concerning all open treatment options for this condition while identifying knowledge gaps and introducing a treatment algorithm. METHODS: Literature search was conducted, including PubMed, Cochrane library, ScienceDirect and Ovid MEDLINE from 2000 to May 2020. Inclusion criteria were set as: (i) clinical studies reporting outcomes following open surgical treatment of acute or chronic hip abductor tendon tears, (ii) studies reporting an open direct or augmented suturing or muscle transfer procedure, (iii) acute or chronic tears found in native or prosthetic hips. RESULTS: A total of 34 studies published between 2004 and 2020 were included. The vast majority of studies were uncontrolled case series of a single treatment method. A total of 970 patients (76% women) with an age range between 48 and 76 years were involved. Women between 60 and 75 years old were most commonly treated. Preoperative evaluation of patients and reporting of open surgical technique and outcomes are inconsistent. All studies reported variable improvement of pain, functional outcomes and gait of patients. Overall, complication rates ranged from 0 to 31.2%. CONCLUSION: The current literature on this topic is highly heterogeneous, and the overall level of the available evidence is low. A roadmap to develop practical guidelines for open surgery of acute and chronic tears of abductor tendons is provided. The anatomy and chronicity of the lesion, the extent of fatty infiltration and neurologic integrity of hip abductor muscles may influence both treatment choice and outcome. Further high-quality studies with standardisation of preoperative evaluation of patients and reporting of outcomes will help delineate best treatments. LEVEL OF EVIDENCE: IV.

Abductor Muscle Strength Deficit in Patients After Total Hip Arthroplasty: A Systematic Review and Meta-Analysis.

BACKGROUND: The aims of this study were to assess and quantify hip abductor muscle strength deficits after total hip arthroplasty (THA) and to determine associations with external factors. METHODS: Studies reporting on hip abductor muscle strength before and/or after THA performed for osteoarthritis or atraumatic osteonecrosis of the hip were considered for inclusion. Data sources were Embase, Medline, and the Cochrane Central Register of Controlled Trials. Muscle strength on the affected side was compared with the healthy contralateral side or with control subjects. Study quality was assessed using a modified Newcastle-Ottawa Scale. RESULTS: Nineteen studies reporting on 875 subjects met the inclusion criteria. Patients scheduled for THA had a mean strength deficit of 18.6% (95% confidence interval (CI) [-33.9, -3.2%]) compared with control subjects. Abductor muscle strength then increased by 20.2% (CI [5.6, 34.8%]) at 4-6 months, 29.6% (CI [4.7, 54.4%]) at 9-12 months, and 49.8% (CI [-31.0, 130.6%]) at 18-24 months postoperatively compared with preoperative values. For unilateral THA, the mean torque ratio was 86.3% (CI [75.4, 97.2%]) and 93.4% (CI [75.1, 111.6%]) before and >24 months after THA, respectively. Study quality was low to moderate. CONCLUSION: Hip abductor muscle strength deficits may gradually improve during 24 months after THA possibly without complete recovery. Cautious interpretation of these findings is warranted because high-quality evidence is largely missing.

Asymptomatic Gluteal Tendinopathies Negatively Impact Outcomes of Total Hip Arthroplasty: A Propensity Score-Matched Study.

BACKGROUND: The purpose of this study is to compare outcomes after total hip arthroplasty (THA) in patients with preoperative asymptomatic gluteus medius and minimus (GMM) pathology to a control group with no GMM pathology. METHODS: Patients undergoing THA for osteoarthritis between August 2012 and March 2018 were retrospectively reviewed. Asymptomatic GMM pathology was considered as the presence of gluteal tendinopathy diagnosed by magnetic resonance imaging (MRI) without the following clinical symptoms: Trendelenburg gait or test, abductor weakness, and lateral thigh tenderness. Patients with asymptomatic GMM pathology were matched (1:1) to patients without GMM pathology on MRI. Two-year data were collected on patient-reported outcomes including Harris Hip Score, Forgotten Joint Score, pain, and satisfaction. Postoperative clinical examination, radiographic measures, complications, and revisions for both groups were reviewed. RESULTS: Fifty cases of asymptomatic GMM pathology were successfully matched to 50 hips without GMM pathology on MRI. Patients with asymptomatic GMM pathology demonstrated significantly worse outcomes regarding 2-year Harris Hip Score (86.24 vs 92.39, P = .04), VAS for pain (1.82 vs 0.98, P = .05), and patient satisfaction (7.69 vs 9.16, P = .002). The study group exhibited significantly higher rates of lateral hip pain postoperatively. Two cases (4%) in the control group underwent a revision THA and 4 cases (8%) in the study group underwent revision THA. CONCLUSION: In patients undergoing THA for osteoarthritis, those with asymptomatic GMM pathology experience inferior 2-year postoperative patient-reported outcomes compared to a matched group. This finding should raise awareness surrounding this important pathology's negative impact on surgical outcomes, thus warranting increased vigilance, and possibly justifying concomitant treatment, even in cases of asymptomatic GMM tears. LEVEL OF EVIDENCE: Level III - Retrospective comparative prognostic study.

Iatrogenic gluteus medius muscle insertion injury while trochanteric entry nailing due to trochanteric fractures: a comparative study in forty patients with gray-scale ultrasound and shear-wave elastography.

INTRODUCTION: Trochanteric entry nailing potentially causes damage to the gluteus medius (GM) tendon. The aim of this study is to determine the amount of iatrogenic damage to the tendon during reaming by measuring the thickness and stiffness of the GM muscle in patients with trochanteric fractures who are treated with trochanteric entry nails using gray-scale ultrasound (GSUS) and shear-wave elastography (SWE). METHODS: Thickness and stiffness values of bilateral GM muscles in 40 patients with trochanteric fractures treated with PFN-A were measured using GSUS and SWE at post-operative sixth week or later. Harris Hip Scores and bilateral active hip abduction measurements of the patients were recorded. The data was analyzed using statistical methods to assess the extent and amount of iatrogenic injury that occurred during trochanteric entry. RESULTS: Mean age of the patients was 70. Thirty-three fractures occurred with low-energy trauma. In the SWE evaluation, there was no statistically significant difference between ipsi- and contralateral GM muscle thickness measurements or ipsi- and contralateral GM muscle stiffness measurements. Also, the difference between the clinical evaluation results of the ipsi- and contralateral hip functions was not statistically significant. DISCUSSION: In this study, we used the Harris Hip Score and hip abduction range of motion in addition to SWE and GSUS in order to assess the patients' functional status. There are studies in the literature that report significant injury to the GM tendon with cephalomedullary nailing. The majority of these studies are cadaver studies with only clinically irrelevant or uncertain evidence. In this study, we aimed to evaluate the potential negative effects of the iatrogenic damage to the bone-tendon junction during nailing, by measuring the stiffness (consistency) and atrophy of the GM muscle alongside the functional evaluation. CONCLUSION: We have found no statistically significant difference between operated and intact side GM muscles in terms of stiffness, atrophy, and functional evaluation in patients with TFs treated using PFN-A. The results of our study should not be interpreted as trochanteric entry nailing does not cause any damage on the GM tendon.

Hip and Trunk Muscle Activity and Mechanics During Walking With and Without Unilateral Weight.

Pelvic drop is caused by decreased hip abductor muscle activity and is associated with lower-extremity injury. Hip abductor strengthening exercises are well established; however, no standard method exists to increase hip abductor activity during functional activities. The purpose of this research was to study the effects of walking with a unilateral weight. A total of 26 healthy adults walked on an instrumented treadmill with and without handheld weight (15%-20% body weight). Muscle activity, kinematic, and kinetic data were collected using surface electromyography, motion capture, and force plates, respectively. Average hip and trunk muscle activity, hip, pelvic, and trunk angles, and peak internal hip moments during stance were compared for each side (contralateral/ipsilateral to the weight) between conditions (unweighted/weighted) using a generalized linear model with generalized estimating equation correction. Interactions between condition and side were observed for muscle activity, frontal plane pelvic and trunk angles, and frontal plane hip moments (P ≤ .003). Compared with the unweighted condition, the weighted condition had higher hip abductor activity contralateral to the weight (P < .001), while no change was found ipsilateral to the weight (P ≥ .790). Similar changes were found for kinematic and kinetic variables. Walking with a unilateral weight may be a therapeutic option to increase functional hip abductor activity.