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Bone & Joint 360
Vol. 13, Issue 5 | Pages 34 - 37
1 Oct 2024

The October 2024 Shoulder & Elbow Roundup360 looks at: Proximal humeral fractures with vascular compromise; Outcomes and challenges of revision arthroscopic rotator cuff repair: a systematic review; Evaluating treatment effectiveness for lateral elbow tendinopathy: a systematic review and network meta-analysis; Tendon transfer techniques for irreparable subscapularis tears: a comparative review; Impact of subscapularis repair in reverse shoulder arthroplasty; Isolated subscapularis tears strongly linked to shoulder pseudoparesis; Nexel and Coonrad-Morrey total elbow arthroplasties show comparable revision rates in New Zealand study; 3D MRI matches 3D CT in assessing bone loss and shoulder morphology in dislocation cases.


The Bone & Joint Journal
Vol. 106-B, Issue 5 Supple B | Pages 89 - 97
1 May 2024
Scholz J Perka C Hipfl C

Aims

There is little information in the literature about the use of dual-mobility (DM) bearings in preventing re-dislocation in revision total hip arthroplasty (THA). The aim of this study was to compare the use of DM bearings, standard bearings, and constrained liners in revision THA for recurrent dislocation, and to identify risk factors for re-dislocation.

Methods

We reviewed 86 consecutive revision THAs performed for dislocation between August 2012 and July 2019. A total of 38 revisions (44.2%) involved a DM bearing, while 39 (45.3%) and nine (10.5%) involved a standard bearing and a constrained liner, respectively. Rates of re-dislocation, re-revision for dislocation, and overall re-revision were compared. Radiographs were assessed for the positioning of the acetabular component, the restoration of the centre of rotation, leg length, and offset. Risk factors for re-dislocation were determined by Cox regression analysis. The modified Harris Hip Scores (mHHSs) were recorded. The mean age of the patients at the time of revision was 70 years (43 to 88); 54 were female (62.8%). The mean follow-up was 5.0 years (2.0 to 8.75).


Bone & Joint Research
Vol. 13, Issue 4 | Pages 169 - 183
15 Apr 2024
Gil-Melgosa L Llombart-Blanco R Extramiana L Lacave I Abizanda G Miranda E Agirre X Prósper F Pineda-Lucena A Pons-Villanueva J Pérez-Ruiz A

Aims

Rotator cuff (RC) injuries are characterized by tendon rupture, muscle atrophy, retraction, and fatty infiltration, which increase injury severity and jeopardize adequate tendon repair. Epigenetic drugs, such as histone deacetylase inhibitors (HDACis), possess the capacity to redefine the molecular signature of cells, and they may have the potential to inhibit the transformation of the fibro-adipogenic progenitors (FAPs) within the skeletal muscle into adipocyte-like cells, concurrently enhancing the myogenic potential of the satellite cells.

Methods

HDACis were added to FAPs and satellite cell cultures isolated from mice. The HDACi vorinostat was additionally administered into a RC injury animal model. Histological analysis was carried out on the isolated supra- and infraspinatus muscles to assess vorinostat anti-muscle degeneration potential.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_11 | Pages 6 - 6
7 Jun 2023
Declercq J Vandeputte F Corten K
Full Access

Tenotomy of the iliopsoas tendon has been described as an effective procedure to treat refractive groin pain induced by iliopsoas tendinitis. However, the procedure forces the rectus femoris to act as the primary hip flexor and little is known about the long-term effects of this procedure on the peri-articular muscle envelope (PAME). Studies suggest that iliopsoas tenotomy results in atrophy of the iliopsoas and decreased hip flexion strength with poorer outcomes, increasing the susceptibility for secondary tendinopathy. The aim of this study is to describe changes in the PAME following psoas release. All patients who presented for clinical examination at our hospital between 2016 and 2021 were retrospectively reviewed. Patients who presented after psoas tenotomy with groin pain and who were unable to actively lift the leg against gravity, were included. Pelvic MRI was taken. Qualitative muscle evaluation was done with the Quartile classification system. Quantitative muscle evaluation was done by establishing the cross-sectional area (CSA). Two independent observers evaluated the ipsi- and contralateral PAME twice. The muscles were evaluated on the level: iliacus, psoas, gluteus minimus-medius-maximus, rectus femoris, tensor fasciae lata, piriformis, obturator externus and internus. For the qualitative evaluation, the intra- and inter-observer reliability was calculated by using kappastatistics. A Bland-Altman analysis was used to evaluate the intra- and inter-observer reliability for the quantitative evaluation. The Wilcoxon test was used to evaluate the changes between the ipsi- and contra-lateral side. 17 patients were included in the study. Following psoas tenotomy, CSA reduced in the ipsilateral gluteus maximus, if compared with the contralateral side. Fatty degeneration occurred in the tensor fascia latae. Both CSA reduction and fatty degeneration was seen for psoas, iliacus, gluteus minimus, piriformis, obturator externus and internus. No CSA reduction and fatty degeneration was seen for gluteus medius and rectus femoris. Conclusions/Discussion. Following psoas tenotomy, the PAME of the hip shows atrophy and fatty degeneration. These changes can lead to detrimental functional problems and may be associated with debilitating rectus femoris tendinopathy. In patients with psoas tendinopathy, some caution is advised when considering an iliopsoas tenotomy


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_2 | Pages 29 - 29
10 Feb 2023
Gupta A Jomaa M Ker A Hollman F Singh N Maharaj J Cutbush K
Full Access

Massive posterosuperior cuff tears (mRCT) retracted to the glenoid are surgically challenging and often associated with high retear rates. Primary repair is a less-favourable option and other salvage procedures such as SCR and tendon transfers are used. This study presents clinical and radiological outcomes of muscle advancement technique for repair of mRCT. Sixty-one patients (mean age 57±6, 77% males and 23% females) (66 shoulders) underwent all-arthroscopic rotator cuff repair that included supraspinatus and infraspinatus subperiosteal dissection off scapular bony fossae, lateral advancement of tendon laminae, and tension-free double-layer Lasso Loop repair to footprint. Pre-and post-operative range of motion (ROM), cuff strength, VAS, Constant, ASES, and UCLA scores were assessed. Radiologic assessment included modified Patte and Goutallier classifications. All patients had MRI at 6 months to evaluate healing and integrity of repair was assessed using Sugaya classification with Sugaya 4 and 5 considered retears. Advanced fatty degeneration (Goutallier 3-4) was present in 44% and 20% of supraspinatus and infraspinatus. Tendon retraction was to the level of or medial to glenoid in 22%, and just lateral in 66%. 50.8% mRCT extended to teres minor. Subscapularis was partially torn (Lafosse 1-3) in 46% and completely torn (Lafosse 4-5) in 20%. At mean follow-up (52.4 weeks), a significant increase in ROM, Relative Cuff Strength (from 57% to 90% compared to contralateral side), VAS (from 4 ±2.5 to 1±1.7), Constant (50±17.8 to 74 ±13.0), ASES (52 ±17.5 to 87 ±14.9), and UCLA (16± 4.9 to 30 ±4.9) scores were noted. There were six retears (10%), one failure due to P. acnes infection. 93% returned to pre-injury work and 89% of cases returned to pre-injury sport. Satisfaction rate was 96%. Muscle advancement technique for mRCT is a viable option with low retear rates, restoration of ROM, strength, and excellent functional outcomes


The Bone & Joint Journal
Vol. 104-B, Issue 11 | Pages 1234 - 1241
1 Nov 2022
Park JH Park KT Kim SC Bukhary HA Lee SM Yoo JC

Aims

This study compared patients who underwent arthroscopic repair of large to massive rotator cuff tears (LMRCTs) with isolated incomplete repair of the tear and patients with incomplete repair with biceps tendon augmentation. We aimed to evaluate the additional benefit on clinical outcomes and the capacity to lower the re-tear rate.

Methods

We retrospectively reviewed 1,115 patients who underwent arthroscopic rotator cuff repair for full-thickness tears between October 2011 and May 2019. From this series, we identified 77 patients (28 male, 49 female) with a mean age of 64.1 years (50 to 80). Patients were classified into groups A (n = 47 incomplete) and B (n = 30 with biceps augmentation) according to the nature of their reconstruction. Clinical scores were checked preoperatively and at six months, one year, and two years postoperatively. In preoperative MRI, we measured the tear size, the degree of fatty infiltration, and muscle volume ratio of the supraspinatus. In postoperative MRI, the integrity of the repaired rotator cuff tendon was assessed using the Sugaya classification. Tendon thickness at the footprint was evaluated on T2-weighted oblique coronal view.


Bone & Joint Research
Vol. 11, Issue 7 | Pages 453 - 464
20 Jul 2022
Wang H Shi Y He F Ye T Yu S Miao H Liu Q Zhang M

Aims

Abnormal lipid metabolism is involved in the development of osteoarthritis (OA). Growth differentiation factor 11 (GDF11) is crucial in inhibiting the differentiation of bone marrow mesenchymal stem cells into adipocytes. However, whether GDF11 participates in the abnormal adipogenesis of chondrocytes in OA cartilage is still unclear.

Methods

Six-week-old female mice were subjected to unilateral anterior crossbite (UAC) to induce OA in the temporomandibular joint (TMJ). Histochemical staining, immunohistochemical staining (IHC), and quantitative real-time polymerase chain reaction (qRT-PCR) were performed. Primary condylar chondrocytes of rats were stimulated with fluid flow shear stress (FFSS) and collected for oil red staining, immunofluorescence staining, qRT-PCR, and immunoprecipitation analysis.


The Bone & Joint Journal
Vol. 104-B, Issue 3 | Pages 394 - 400
1 Mar 2022
Lee KJ Kim YT Choi M Kim SH

Aims. The aim of this study was to compare the characteristics and outcomes of L-shaped and reverse L-shaped rotator cuff tears. Methods. A total of 82 shoulders (81 patients) after arthroscopic rotator cuff repair were retrospectively enrolled. The mean age of the patients was 62 years (SD 6), 33 shoulders (40.2%) were in male patients, and 57 shoulders (69.5%) were the right shoulder. Of these, 36 shoulders had an L-shaped tear (group L) and 46 had a reverse L-shaped tear (group RL). Both groups were compared regarding characteristics, pre- and postoperative pain, and functional outcomes. Muscle status was assessed by preoperative MRI, and re-tear rates by postoperative ultrasonography or MRI. Results. Patients in group RL were significantly older than in group L (p = 0.008), and group RL was significantly associated with female sex (odds ratio 2.5 (95% confidence interval 1.03 to 6.32); p = 0.041). Mean postoperative pain visual analogue scale (VAS) score was significantly greater (group L = 0.8 (SD 1.5), group RL = 1.7 (SD 2.2); p = 0.033) and mean postoperative American Shoulder and Elbow Surgeons (ASES) score was significantly lower in group RL than group L (group L = 91.4 (SD 13.1), group RL = 83.8 (SD 17.9); p = 0.028). However, postoperative mean VAS for pain and ASES score were not lower than the patient-acceptable symptom state scores. Mean retracted tear length was significantly larger in group L (group L = 24.6 mm (SD 6.5), group RL = 20.0 mm (SD 6.8); p = 0.003). Overall re-tear rate for 82 tears was 11.0% (nine shoulders), and re-tear rates in group L and RL were similar at 11.1% (four shoulders) and 10.9% (five shoulders), respectively (p = 1.000). No significant intergroup difference was found for fatty degeneration (FD) or muscle atrophy. Within group L, postoperative FD grades of supraspinatus and subscapularis worsened significantly (p = 0.034 and p = 0.008, respectively). Mean postoperative pain VAS (male = 1.2 (SD 1.8), female = 1.3 (SD 2.0)) and ASES scores (male = 88.7 (SD 15.5), female = 86.0 (SD 16.8)) were similar in male and female patients (p = 0.700 and p = 0.475, respectively). Regression analysis showed age was not a prognostic factor of postoperative pain VAS or ASES scores (p = 0.188 and p = 0.150, respectively). Conclusion. Older age and female sex were associated with reverse L-shaped tears. Although the postoperative functional outcomes of patients with reverse L-shaped tears were satisfactory, the clinical scores were poorer than those of patients with L-shaped tears. Surgeons should be aware of the differences in clinical outcome between L-shaped and reverse L-shaped rotator cuff tears. Cite this article: Bone Joint J 2022;104-B(3):394–400


Bone & Joint 360
Vol. 10, Issue 6 | Pages 29 - 32
1 Dec 2021


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_13 | Pages 117 - 117
1 Nov 2021
Longo UG
Full Access

The function of the upper extremity is highly dependent on correlated motion of the shoulder. The shoulder can be affected by several diseases. The most common are: rotator cuff tear (RCT), shoulder instability, shoulder osteoarthritis and fractures. Rotator cuff disease is a common disorder. It has a high prevalence rate, causing high direct and indirect costs. The appropriate treatment for RCT is debated. The American Academy Orthopaedic Surgeons guidelines state that surgical repair is an option for patients with chronic, symptomatic full-thickness RCT, but the quality of evidence is unconvincing. Thus, the AAOS recommendations are inconclusive. We are performing a randomized controlled trial to compare surgical and conservative treatment of RCT, in term of functional outcomes, rotator cuff integrity, muscle atrophy and fatty degeneration. Shoulder instability occurs when the head of the upper arm bone is forced out of the shoulder socket. Shoulder instabilities have been classified according to the etiology, the direction of instability, or on combinations thereof. The Thomas and Matsen classification, which is currently the most commonly utilized classification, divides shoulder instability events into the traumatic, unidirectional, Bankart lesion, and surgery (TUBS) and the atraumatic, multidirectional, bilateral, rehabilitation, and capsular shift (AMBRI) categories. The acquired instability overstress surgery (AIOS) category was then added. Surgical procedures for shoulder instability includes arthroscopic capsuloplasty, remplissage, bone block procedure or Latarjet procedure. Reverse total shoulder arthroplasty (RTSA) represents a good solution for the management of patients with osteoarthritis or fracture of the proximal humerus, with associated severe osteoporosis and RC dysfunction


The Bone & Joint Journal
Vol. 103-B, Issue 10 | Pages 1619 - 1626
1 Oct 2021
Bi M Zhou K Gan K Ding W Zhang T Ding S Li J

Aims. The aim of this study is to provide a detailed description of cases combining bridging patch repair with artificial ligament “internal brace” reinforcement to treat irreparable massive rotator cuff tears, and report the preliminary results. Methods. This is a retrospective review of patients with irreparable massive rotator cuff tears undergoing fascia lata autograft bridging repair with artificial ligament “internal brace” reinforcement technique between January 2017 and May 2018. Inclusion criteria were: patients treated arthroscopically for an incompletely reparable massive rotator cuff tear (dimension > 5 cm or two tendons fully torn), stage 0 to 4 supraspinatus fatty degeneration on MRI according to the Goutallier grading system, and an intact or reparable infraspinatus and/or subscapularis tendon of radiological classification Hamada 0 to 4. The surgical technique comprised two components: first, superior capsular reconstruction using an artificial ligament as an “internal brace” protective device for a fascia lata patch. The second was fascia lata autograft bridging repair for the torn supraspinatus. In all, 26 patients with a mean age 63.4 years (SD 6.2) were included. Results. All patients underwent more than two years of follow-up (mean 33.5 months (24 to 45)). All clinical scores were also improved at two-year follow-up (mean visual analogue scale 0.7 (SD 0.5) vs 6.1 (SD 1.2); p < 0.001; mean American Shoulder and Elbow Surgeons score 93.5 (SD 5.3) vs 42.5 (SD 10.8); p < 0.001; mean University of California, Los Angeles score, 31.7 (SD 3.7) vs 12.0 (SD 3.1); p < 0.001; and mean Constant-Murley score 88.7 (SD 3.5) vs 43.3 (SD 10.9); p < 0.001), and 24 of 26 fascia lata grafts were fully healed on MRI (92%). One patient had haematoma formation at the harvesting side of the fascia lata at two days postoperatively. Conclusion. The fascia lata autograft bridging repair combined with artificial ligament internal brace reinforcement technique achieved good functional outcomes, with a high rate of graft healing at two-year follow-up. Although the short-term results are promising, further studies with a greater number of patients would provide clearer results. Cite this article: Bone Joint J 2021;103-B(10):1619–1626


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_11 | Pages 29 - 29
1 Sep 2021
Lee C Lee MG Lim WJ Liu Y Pakdeenit B Kim JS
Full Access

Although interlaminar endoscopic lumbar discectomy (IELD) is considered to be less invasive than microscopic lumbar discectomy (MLD) in treatment of lumbar herniated nucleus pulposus, the radiologic change of multifidus muscles by each surgery has rarely been reported. The aim of the present study was to compare the quantitative and qualitative changes of multifidus muscles between two surgical approaches and to analyze the correlation between various parameters of multifidus muscles and long term surgical outcome. 21 patients who received MLD and 18 patients who received IELD in a single tertiary hospital were enrolled and their preoperative, postoperative (≤15 days), and follow-up (≥6 months) MRIs were analyzed. The cross-sectional area (CSA) and fatty degeneration rate (FD) were quantitatively estimated at the level of surgery. The correlations among CSA, FD, body mass index, follow-up visual analogue scale(VAS) and Oswestry Disability Index(ODI) were assessed. Mean intervals of postoperative MRI and follow-up MRI from surgery were 3.0±3.7 days and 14.5±10.7 months, respectively. During the follow-up period, VAS was improved from 7.1±1.3 to 2.1±1.8 in MLD and from 8.2±1.4 to 2.2±1.8 in IELD. In cases of MLD, comparing with preoperative MRI, ipsilateral CSA was significantly increased in postoperative MRI (795.6mm. 2. vs. 906.5mm. 2. , p<0.01), but it was not significantly different in follow-up MRI (795.6mm. 2. vs. 814.4mm. 2. , p=1.00). However, in case of IELD, the ipsilateral CSAs in preoperative, postoperative, and follow-up periods were 892.0 mm. 2. , 909.3 mm. 2. , and 900.3 mm. 2. , respectively. These changes were not significant over time (p=0.691). The ipsilateral FDs were not significantly changed between preoperative and follow-up periods in both MLD (21.4% vs. 20.9%, p=0.81) and IELD groups (23.5% vs. 21.8%, p=0.19). The increment of ipsilateral CSA had significant correlations with follow-up ODI (r=−0.368, p=0.02). Comparing with IELD, MLD induced more surgical trauma on multifidus muscle in postoperative period, but the muscular damage was recovered in follow-up period. IELD can minimize surgical trauma on multifidus muscle showing similar pain relief as MLD. Favorable surgical outcome in follow-up period may be related to increment of multifidus muscle volume. Figure 1. (A-C) The multifidus muscles in preoperative, postoperative, and follow-up periods, respectively, in patient with MLD. Comparing with preoperative period, the CSA of right multifidus muscle (ipsilateral side) was increased in postoperative period, but recovered in follow-up period. (D-F) The multifidus muscle in preoperative, postoperative, and follow-up periods, respectively, in patient with IELD. The CSA of left multifidus muscles (ipsilateral side) was not significantly changed over time. Comparing preoperative MRIs with follow-up MRIs, the FDs of multifidus muscles were not significantly changed regardless of surgical technique. Figure 2. The CSA was measured by marking region of interest (ROI) and FD was measured by calculating the rate of pixels beyond the threshold in ROI. All measurements were performed using ImageJ software (version 1.52a, National Institutes of Health, Bethesda, Maryland, USA). For any figures or tables, please contact the authors directly


Bone & Joint 360
Vol. 8, Issue 6 | Pages 39 - 41
1 Dec 2019


Bone & Joint 360
Vol. 8, Issue 6 | Pages 18 - 19
1 Dec 2019


Bone & Joint 360
Vol. 8, Issue 3 | Pages 40 - 42
1 Jun 2019


Bone & Joint 360
Vol. 7, Issue 6 | Pages 26 - 28
1 Dec 2018


The Bone & Joint Journal
Vol. 100-B, Issue 4 | Pages 485 - 492
1 Apr 2018
Gauci MO Bonnevialle N Moineau G Baba M Walch G Boileau P

Aims

Controversy about the use of an anatomical total shoulder arthroplasty (aTSA) in young arthritic patients relates to which is the ideal form of fixation for the glenoid component: cemented or cementless. This study aimed to evaluate implant survival of aTSA when used in patients aged < 60 years with primary glenohumeral osteoarthritis (OA), and to compare the survival of cemented all-polyethylene and cementless metal-backed glenoid components.

Materials and Methods

A total of 69 consecutive aTSAs were performed in 67 patients aged < 60 years with primary glenohumeral OA. Their mean age at the time of surgery was 54 years (35 to 60). Of these aTSAs, 46 were undertaken using a cemented polyethylene component and 23 were undertaken using a cementless metal-backed component. The age, gender, preoperative function, mobility, premorbid glenoid erosion, and length of follow-up were comparable in the two groups. The patients were reviewed clinically and radiographically at a mean of 10.3 years (5 to 12, sd 26) postoperatively. Kaplan–Meier survivorship analysis was performed with revision as the endpoint.


Bone & Joint 360
Vol. 6, Issue 6 | Pages 25 - 28
1 Dec 2017


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_7 | Pages 123 - 123
1 Apr 2017
Cameron H
Full Access

Hip fusion is an uncommon procedure. Hip fusion takedown, therefore, is equally an uncommon procedure. What is of considerable interest is that the results, which I achieved in 20 cases in a paper published in 1987 are considerably superior to the results, which I am achieving today. This suggests that no simple case is now fused. It also equally suggests that there is little sense in looking at literature more than 10 or 15 years old on fusion takedowns as the two conditions are likely completely different. Most patients do not like a hip fusion. There are long-term problems with low back pain, ipsilateral global instability and contralateral patellofemoral osteoarthritis. A stiff hip produces a poor quality of life, especially in a tall person. The main problem in doing a hip fusion takedown is the condition of the abductors muscles. If fused before growth was complete, there may be pelvic hypoplasia. If the pelvis is small, the glutei will also be small. Sometimes, the glutei may have undergone fatty degeneration. This can be assessed by means of an MRI. If the abductors were damaged during fusion, a limp may persist. Other problems are that leg lengthening is difficult to achieve any longstanding hip fusion. Lengthening of 1–2 cm is usually about all that can safely be achieved. If the hip was fused in childhood, there is likely to be femoral hypoplasia. There is also likely absence of proximal cancellous bone and the proximal femur is a thin brittle cortical tube. The greater trochanter should not be detached as it is difficult to obtain union under such circumstances. The approach, which I prefer for a fusion takedown is an anterior Smith Peterson. The glutei are slid off the pelvis sidewall and then the upper part of the fusion can be exposed, blunt Hohmans can then be passed around the femoral neck prior to transection. Obviously, if any AO cobra plate has been used for a fusion, a trochanteric osteotomy may be required to preserve any glutei left. Old hardware can be removed either concurrently or as an interval procedure. In 1986, I published the results of 20 cases with a five to 40-year fusion time (mean 19). I used a variety of implants. Flexion was achieved to 90 degrees at 12 months in about 88% of people. Seventy-five percent ceased to limp by year one, although the elderly limp when tired. One patient was dissatisfied with the procedure. One was revised for pain. I have reviewed the cases done in the last 20 years. These were 28 cases, two bilateral. Seven were spontaneous fusions. Twenty-one were formal hip fusions. One was an AO fusion with a cobra plate. There were various intra-operative complications including two calcar cracks, which were wired, three femoral shaft fractures, which necessitated the use of long stems. There was one drop foot, which recovered. At review, a limp was absent in 20%, mild in 12% and severe, i.e. Trendelenburg positive in 68%. Harris hip scores were excellent in 28%, good in 32%, fair in 16% and poor in 24%. Four patients only, however, continued to use canes. The eventual range of movement was good. In 80%, more than 90 degrees of flexion was obtained, but it took up to two years to obtain maximum flexion. In 12%, the range of motion was poor at being 50 degrees to 85 degrees. The range of motion was poor, i.e. less than 45 degrees in one bilateral case of athrogryposis. This was a stiff arthrogrypotic. Further surgery is required in several cases. An ipsilateral total knee replacement and one a supracondylar femoral osteotomy. One cup loosened and was revised at seven years and one liner was exchanged at ten years


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_6 | Pages 39 - 39
1 Mar 2017
Takao M Ogawa T Yokota F Otake Y Hamada H Sakai T Sato Y Sugano N
Full Access

Introduction. Patients with hip osteoarthritis have a substantial loss of muscular strength in the affected limb compared to the healthy limb preoperatively, but there is very little quantitative information available on preoperative muscle atrophy and degeneration and their influence on postoperative quality of life (QOL) and the risk of falls. The purpose of the present study were two folds; to assess muscle atrophy and degeneration of pelvis and thigh of patients with unilateral hip osteoarthritis using computed tomography (CT) and to evaluate their impacts on postoperative QOL and the risk of falls. Methods. We used preoperative CT data of 20 patients who underwent primary total hip arthroplasty. The following 17 muscles were segmented with our developed semi-automated segmentation method: iliacus, gluteus maximus, gluteus medius, gluteus minimus, rectus femoris, tensor facia lata, adductors, pectinus, piriformis, obturator externus, obturator internus, semimenbranosus, semitendinosus, vastus medialis and vastus lateralis/intermedius (Fig. 1). Volume and radiological density of each muscle were measured. The ratio of those of affected limb to healthy limb was calculated. At the latest follow-up, the WOMAC score was collected and a history of falls after surgery was asked. The average follow- up period was 6 years. Comparison of the volume and radiological density of each muscle between affected and healthy limbs was performed using the Wilcoxon signed rank test. Correlations between the volume and radiological density of each muscle and each score of the WOMAC were evaluated with Spearman's correlation coefficient. The volume and radiological density of each muscle between patients with and without a history of falls were compared using Mann-Whitney U test. Results. 13 of 17 muscles showed significant decrease in muscle volume in affected limb compared to healthy limb. The mean muscle atrophy ratio was 18.6±7.1 (SD) % (0–28.3%). Iliacus, psoas, adductors and piriformis showed a significant volume reduction more than 25 %. All 17 muscles showed reduced radiological density along the affected limb compared to the healthy side. The difference was 8.7±4.2 (SD) Hounsfield units (3.2 to 16.4). Gluteus medius and gluteus minimus showed a significant decrease of radiological density more than 15 HU. The radiological density of gluteus minimus showed higher correlation (R>0.7) with physical function scores of WOMAC for descending stairs, rising from sitting, walking on flat surface, going shopping and rising from bed. Seven of 20 patients had a history of falls, who showed significant reduced radiological density of gluteus minimus and obturator internus compared to the 13 patients without a history of falls. Conclusion. Almost all muscles of pelvis and thigh along the affected limb showed marked atrophy and fatty degeneration compared to the healthy side. Especially, the degree of fatty degeneration of gluteus minimus showed significant impacts on postoperative physical function and the risk of falls of patients