Rehabilitation following periacetabular osteotomy for acetabular dysplasia: A qualitative interview study exploring challenges, hopes and expectations among patients in Denmark and Australia.

INTRODUCTION: Guidelines have been proposed for post-operative rehabilitation following periacetabular osteotomy (PAO). However, the perspectives of individuals undergoing PAO have not been considered. AIM: The present study aimed to explore the perceived challenges of everyday life and hopes for and expectations of post-PAO rehabilitation from the perspective of individuals with acetabular dysplasia living in Denmark and Australia. METHODS: In this qualitative study, we used a hermeneutic phenomenological approach with semi-structured interviews to explore the perspectives of 25 participants (four males), aged 16-43 years, who underwent a PAO. Purposeful sampling was used to provide variations in age and sex. Inclusion criteria were age above 15 years, radiographic evidence of acetabular dysplasia, PAO within the last seven weeks and undergoing post-operative rehabilitation. Inductive content analysis was adopted to code and analyse interviews. RESULTS: The analysis of the interview transcripts revealed four major themes: different expectations, self-confidence, tailored rehabilitation and aligning expectations. Several subthemes emerged within each theme, and similar patterns with minor variations were identified across countries. However, the financial burden of self-funded surgery and rehabilitation challenged some Australian participants, whereas none of the Danish participants mentioned this challenge. CONCLUSION: Our findings elucidate the diverse range of hopes and expectations in individuals undergoing PAO, and how these relate to their perceived challenges. In particular, the findings highlight the importance of aligning expectations between individuals and clinicians when designing the rehabilitation.

The anatomical location of cystic pseudotumors and muscle atrophy in metal-on-metal resurfacing hip arthroplasty is related to the surgical approach used for implantation. A subgroup analyses of a randomized controlled trial.

BACKGROUND: Pseudotumors and muscle atrophy have been associated with metal-on-metal (MoM) resurfacing hip arthroplasty (RHA). We aimed to investigate the influence of the anterolateral (AntLat) and the posterior (Post) surgical approach on the location, grade and prevalence of pseudotumors and muscle atrophy in MoM RHA. PATIENTS AND METHODS: Forty-nine patients were randomized to MoM RHA by the AntLat (n = 25) or the Post (n = 24) approach at Aarhus University Hospital. Patients underwent metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) scans for investigation of location, grade and prevalence of pseudotumors and muscle atrophy. Plain radiographs, metal-ions concentrations and clinical outcome scores were evaluated to compare outcomes of the surgical approaches. RESULTS: MRI-detected pseudotumors were seen in 7 of 18 patients (39%) in the AntLat group and in 12 of 22 patients (55%) in the Post group (p = 0.33). Pseudotumors were mainly located anterolaterally to the hip joint in the AntLat group and postero-lateral to the hip joint in the Post group. Higher grades of muscle atrophy of the caudal part of the gluteus medius and minimus (p < 0.004) were seen in the AntLat group, and higher grades of muscle atrophy of the small external rotators were seen in the Post group (p < 0.001). The AntLat group had higher anteversion angles of mean 15.3° (range 6.1-7.5) versus mean 11.5° (range 4.9-22.5) in the Post group (p = 0.02). Metal-ion concentrations and clinical outcome scores were similar between groups (p > 0.08). CONCLUSION: Muscle atrophy and pseudotumor location after MoM RHA follow the surgical approach used for implantation. This knowledge may help differentiate between "normal postoperative appearance" and "MoM disease."

Is the Femoral-Epiphyseal Acetabular Roof (FEAR) index associated with hip pain in patients with hip dysplasia?

BACKGROUND: Micro instability of the hip joint has been suggested to cause pain in patients with hip dysplasia. Recently, the Femoral-Epiphyseal Acetabular Roof (FEAR) index has been developed to evaluate hip instability in patients with dysplasia. PURPOSE: To investigate associations between the FEAR index and patient-reported outcomes before and six months after periacetabular osteotomy (PAO). MATERIAL AND METHODS: Radiographs of patients with hip dysplasia who underwent PAO between 2018 and 2020 were retrospectively assessed by a radiologist and an orthopedic surgeon. Radiographic measurements indicative of hip instability (Shenton's line, FEAR index, center-edge angle of Wiberg, acetabular index of Tönnis, and the femoral neck-shaft angle) were measured. Data on hip pain, function, and quality of life were collected prospectively using the Hip dysfunction and Osteoarthritis Outcome Score (HOOS). RESULTS: A total of 222 patients were included in the study. All radiographic measurements and patient-reported outcomes improved significantly from preoperative to six months postoperative (P < 0.001). There were no differences in the change score of patient-reported outcomes between patients with a FEAR index >2° (indicative of hip instability) and patients with a FEAR index ≤2°. CONCLUSION: The FEAR index was not associated with hip pain, function, and quality of life among patients with hip dysplasia. This study did not find evidence supporting that instability defined by the FEAR index caused pain in patients with hip dysplasia.

Migration pattern of cemented Exeter short stem in Dorr type A femurs. A prospective radiostereometry study with 2-year follow-up.

INTRODUCTION: The Exeter short stem (ESS) is 25 mm shorter than the standard length v40 Exeter stem (Stryker) and intended for a narrow femoral diaphysis. The purpose of the study was to evaluate the migration pattern of the cemented ESS. MATERIAL AND METHOD: In a prospective single-center cohort study, 23 patients (21 female) mean age 78 (range 70-89) with hip osteoarthritis and Dorr Type A femurs were included. Preoperative DXA was used to group patients into normal (> - 1) and low (< - 1) T-score. Components were the collarless polished double-tapered Exeter short stem type N°1 L125. Patients were followed for 2 years with model-based RSA (stem migration), regular hip radiographs (stem position and cementation quality), Oxford Hip Score (OHS) and VAS pain. RESULTS: At 2-year follow-up, the stems subsided 1.48 mm (CI 95% 1.69; 1.26) and retroverted 0.45° (CI 95% 0.01; 0.88). From 12 to 24 months, stem subsidence was 0.18 mm (CI 95% 0.1; 0.25) (p = 0.001) and retroversion was - 0.04° (CI 95% - 0.27; 0.18) (p = 0.70). T-score and stem subsidence correlated (rho = 0.48; p = 0.025) and patients with normal T-score (n = 7) had 0.42 mm (CI 95% - 0.01; 0.85) less subsidence as compared to patients with low T-score (n = 15) (p = 0.054). Stems in varus position (n = 9) subsided 1.7 mm (CI 95% 1.35; 2.05) compared to 1.33 mm (CI 95% 1.05; 1.60) for stems in neutral position (n = 13) (p = 0.07). Postoperative cementation quality did not influence 2-year stem migration. OHS improved to 40.7 (CI 95% 36.8; 44.7) and VAS pain at rest and activity decreased to 5 mm and 10 mm, respectively (p < 0.001). CONCLUSION: The 2-year migration pattern of the cemented ESS was similar to reports for the cemented standard length Exeter stem. Low preoperative T-score and varus stem-position showed a tendency for higher stem migration and should be studied as risk factors for failure in larger studies of cemented polished stems.

Trajectory for 66 patients treated with periacetabular osteotomy (PAO) and subsequent total hip arthroplasty: a follow-up study including 1378 hips from the Aarhus PAO database.

INTRODUCTION: Outcomes for patients treated with PAO and subsequent total hip arthroplasty (THA) remain unclear. We evaluated patient-reported outcomes among patients treated with PAO and subsequent THA and investigated differences in the number of additional surgical procedures after PAO among patients treated with PAO and subsequent THA and patients treated with PAO only. MATERIALS AND METHODS: 1378 hips underwent PAO and subsequently 66 hips were treated with THA. We evaluated the Hip disability and Osteoarthritis Outcome Score (HOOS) and physical activity questions for the 66 hips. Additional surgery after PAO was identified through inquiry to the Danish National Patient Registry. RESULTS: 13% undergoing PAO and subsequent THA reported a HOOS pain score ≤ 50 indicating a clinical failure. The risk difference for hip arthroscopy after PAO within 2 and 4 years was 14% (CI 5-23%) and 26% (CI 15-38%) in favor of hips treated with PAO only. Similarly, the risk difference for screw removal within 2 and 4 years was 19% (CI 8-29%) and 23% (CI 12-34%). CONCLUSION: 87% of patients undergoing PAO and subsequent THA had little or no hip pain. However, these patients received a high number of additional surgeries after PAO. Surgeons and patients may consider if additional surgery after PAO may be the first choice in a series of actions leading to conversion to THA.

Comparing exercise and patient education with usual care in the treatment of hip dysplasia: a protocol for a randomised controlled trial with 6-month follow-up (MovetheHip trial).

INTRODUCTION: Surgery is not a viable treatment for all patients with hip dysplasia. Currently, usual care for these patients is limited to a consultation on self-management. We have shown that an exercise and patient education intervention is a feasible and acceptable intervention for patients not receiving surgery. Therefore, we aim to investigate whether patients with hip dysplasia randomised to exercise and patient education have a different mean change in self-reported pain compared with those randomised to usual care over 6 months. Furthermore, we aim to evaluate the cost-effectiveness and perform a process evaluation. METHODS AND ANALYSIS: In a randomised controlled trial, 200 young and middle-aged patients will be randomised to either exercise and patient education or usual care at a 1:1 ratio through permuted block randomisation. The intervention group will receive exercise instruction and patient education over 6 months. The usual care group will receive one consultation on self-management of hip symptoms. The primary outcome is the self-reported mean change in the pain subscale of the Copenhagen Hip and Groin Outcome Score (HAGOS). Secondary outcomes include mean changes in the other HAGOS subscales, in the Short Version of the International Hip Outcome Tool, in performance, balance and maximal hip muscle strength. Between-group comparison from baseline to 6-month follow-up will be made with intention-to-treat analyses with a mixed-effects model. Cost-effectiveness will be evaluated by relating quality-adjusted life years and differences in HAGOS pain to differences in costs over 12 months. The functioning of the intervention will be evaluated as implementation, mechanisms of change and contextual factors. ETHICS AND DISSEMINATION: The study protocol was approved by the Committee on Health Research Ethics in the Central Denmark Region and registered at ClinicalTrials. Positive, negative and inconclusive findings will be disseminated through international peer-reviewed scientific journals and international conferences. TRIAL REGISTRATION NUMBER: NCT04795843.

Dislocation rate, revisions and other complications of primary cemented hemiarthroplasty for displaced femoral neck fractures: a single-center cohort study of 743 unselected hips with a mean 2.7-year follow-up.

INTRODUCTION: Evidence of whether to use hemiarthroplasty (HA) or total hip arthroplasty for displaced femoral neck fractures (FNF) is still widely debated, especially when taking ambulatory status, age, and patient cognitive status into account. The current study aims to report the rates of dislocations, revisions and other complications for primary cemented HA in patients with displaced FNF. MATERIALS AND METHODS: Single-center retrospective follow-up study of an unselected historic cohort. 743 consecutive hips (551 W and 192 M) at mean (SD) age of 83.6 (8.4) years received primary cemented HA for displaced FNF by posterolateral surgical approach between January 2012 and December 2019. Patient files and radiographs were evaluated for dislocations, revisions, and other complications until death or end of the follow-up period, and the educational level of the surgeon was noted. RESULTS: During a mean (SD) follow-up period of 2.7 (2.2) years, there were 6.1% (n = 45) dislocations, in which 82% (first dislocation) appeared within the first 30 postoperative days, and 51% (n = 23) of the dislocations requiring subsequent surgery. At the time of the last available follow-up, 57% (n = 421) of the patients were dead. A non-dislocation related revision was needed in 3.4% (n = 25) of the patients [in which infection accounted for 40% (n = 10) and traumatic periprosthetic fracture for 32% (n = 8)]. Thirty-day mortality was 9.2% and 1-year mortality 25.8%. There were no differences in patient's age, gender, or educational level of the surgeon between the dislocation and the no dislocation groups. Patients aged < 70 years presented with a higher dislocation rate (p < 0.001) than the patients aged > 70 years. CONCLUSION: Primary HA presents a safe and robust approach with acceptable complication rates in a genuine unselected cohort of displaced FNF, particularly for patients aged > 70.

Isometric hip strength impairments in patients with hip dysplasia are improved but not normalized 1 year after periacetabular osteotomy: a cohort study of 82 patients.

Background and purpose - In patients with hip dysplasia, knowledge of hip muscle strength after periacetabular osteotomy is lacking. We investigated isometric hip muscle strength in patients with hip dysplasia, before and 1 year after periacetabular osteotomy, and compared this with healthy volunteers. Furthermore, we investigated whether pre- to post-surgical changes in self-reported pain and sporting function were associated with changes in isometric hip muscle strength.Patients and methods - Isometric hip muscle strength was assessed twice in 82 patients (11 men) with a mean age of 30 (SD 9) years, before and 1 year after surgery, and once in 50 healthy volunteers. Isometric hip muscle strength was assessed with a hand-held dynamometer. Copenhagen Hip and Groin Outcome Score was used to measure self-reported outcome.Results - Despite 1-year improvements in isometric hip flexion (0.1 Nm/kg; 95% CI 0.06-0.2) and abduction (0.1 Nm/kg; CI 0.02-0.2), the patients' muscle strength was 13-34% lower than the strength of the healthy volunteers both pre- and post-surgery (p < 0.01). Moreover, changes in self-reported pain were associated with changes in hip flexion (13 points per Nm/kg; CI 1-26) and abduction (14 points per Nm/kg; CI 3-25), while changes in self-reported sporting function were associated with changes in hip extension (9 points per Nm/kg; CI 1-18).Interpretation - Isometric hip muscle strength is impaired in symptomatic dysplastic hips measured before periacetabular osteotomy. 1 year after surgery, isometric hip flexion and abduction strength had improved but muscle strength did not reach that of healthy volunteers.

Does pain and hip function improve 2 years after reverse periacetabular osteotomy? A follow-up study of 74 patients.

Data on outcome in patients with acetabular retroversion (AR) treated with reverse periacetabular osteotomy (reverse PAO) are sparse. The aim of the study was to investigate changes in pain and hip function among patients with AR 2 years after reverse PAO and to examine whether changes in pain were associated with changes in hip function. In addition, to evaluate patient satisfaction and changes in quality of life (QoL). We present a prospective follow-up study with patient-reported outcome data from Aarhus University Hospital in Denmark. Pain at rest and during activity was measured with a Visual Analogue Scale (VAS), hip function with the Hip disability and Osteoarthritis Outcome Score (HOOS) and QoL with the Short-Form 36, pre-operatively and 2 years after reverse PAO in 74 patients. Changes were analysed using paired t-test and multiple linear regressions. Significant and clinically relevant mean improvements in pain and hip function were found. The numbers of responders achieving a minimal clinically important difference varied from 51 to 73%. Positive significant association between changes in pain and changes in hip function were found. Significant mean improvement in QoL was found. The study had a loss to follow-up of 23%. Two years after reverse PAO, patients diagnosed with AR showed significant and clinically relevant mean improvements in pain and hip function. Decreased pain was significantly associated with improved hip function. The majority of patients were satisfied with the result of surgery and QoL was similar to the Danish background population.

14-year hip survivorship after periacetabular osteotomy: a follow-up study on 1,385 hips.

Background and purpose - Few studies have evaluated the long- and mid-term outcomes after minimally invasive periacetabular osteotomy (PAO). We investigated: (1) the long-term hip survival rate after PAO; (2) the risk of complications and additional surgery after PAO; and (3) the hip function at different follow-up points.Patients and methods - We reviewed 1,385 hips (1,126 patients) who underwent PAO between January 2004 and December 2017. Through inquiry to the Danish National Patient Registry we identified conversions to total hip arthroplasty (THA) and complications after PAO. We evaluated the Hip disability and Osteoarthritis Outcome Score (HOOS) obtained preoperatively, and at 6 months, 2-, 5-, and 10-years' follow-up.Results - 73 of the 1,385 hips were converted to THA. The overall Kaplan-Meier hip survival rate was 80% (95% CI 68-88) at 14 years with a mean follow-up of 5 years (0.03-14). 1.1% of the hips had a complication requiring surgical intervention. The most common additional surgery was removal of screws (13%) and 11% received a hip arthroscopy. At the 2-year follow-up, HOOS pain improved by a mean of 26 points (CI 24-28) and a HOOS pain score > 50 was observed in 86%.Interpretation - PAO preserved 4 of 5 hips at 14 years, with higher age leading to lower survivorship. The PAO technique was shown to be safe; 1.1% of patients had a complication that demanded surgical intervention. The majority of the patients with preserved hips have no or low pain. The operation is effective with a good clinical outcome.

[Younger patients with hip joint pain].

This review summarises the present knowledge of diagnosing and treating hip joint pain. The results of joint preserving surgery are good in symptomatic patients with hip dysplasia, acetabular retroversion or impingement (cam or pincer) without signs of osteoarthritis. Confirmation of intraarticular pathology as the cause of symptoms is established clinically, and the pathology can in many cases be visualised by a standing, standardised radiograph of the pelvis, which is the basis for admission to the relevant orthopaedic department. We present an algorithm for this. Dysplasia and retroversion can be treated by periacetabular osteotomy and impingement by arthroscopic procedures.

Higher early proximal migration of hemispherical cups with electrochemically applied hydroxyapatite (BoneMaster) on a porous surface compared with porous surface alone: a randomized RSA study with 53 patients.

Background and purpose - BoneMaster (BM) is an electrochemically deposited hydroxyapatite (HA) implant-coating, which is evenly distributed, thin, and quickly resorbed. It is designed to stimulate osseointegration and early implant stability and alleviate longer-term HA-induced third-body polyethylene wear. This study evaluates early cup migration and functional outcomes of cementless porous-coated hemispherical cups with or without BM.Patients and methods - In a patient-blinded, randomized, controlled trial 53 patients at mean 64 years (55-75) with coxarthritis were operated with an Exceed cup (Zimmer Biomet) and Bi-Metric stem (Zimmer Biomet) with porous and BM coating (PBM) or with porous coating alone (P). Follow-ups were performed postoperatively and at 3, 6, 12, and 24 months. Effect measures were cup migration measured with RSA and PROMs.Results - At 6-month follow-up, proximal cup migration in the PBM group (0.09 mm, 95% CI 0.02-0.20) was higher than in the P group (0.25 mm, CI 0.15-0.35). At 1- and 2-year follow-up, cup migration in all 6 degrees of freedom was similar between groups (p > 0.2). From before surgery to 2-year follow-up, Oxford Hip Score (OHS) increased by 17 points (CI 14-20). Hip disability and Osteoarthritis Outcome Score (HOOS) increased in all sub-scores, but was more pronounced for PBM cups compared with P cups in the Symptoms sub-score (p = 0.04).Interpretation - Contrary to expectations, PBM cups had higher early migration than P cups. At 2-year follow-up, migration was similar between groups. There seems to be no early benefit of BM coating on acetabular cups.

Efficacy of periacetabular osteotomy followed by progressive resistance training compared to progressive resistance training as non-surgical treatment in patients with hip dysplasia (PreserveHip) - a protocol for a randomised controlled trial.

INTRODUCTION: Periacetabular osteotomy (PAO) is an established treatment for adolescent and adult patients with hip dysplasia. However, the efficacy of PAO has not been tested against another surgical intervention or conservative treatment in a randomised controlled trial before. We suggest that progressive resistance training (PRT) could be an alternative to PAO. The primary aim of this trial is therefore to examine the efficacy of PAO followed by 4 months of usual care followed by 8 months of PRT compared to 12 months of solely PRT in patients with hip dysplasia eligible for PAO in terms of patient-reported pain measured by The Copenhagen Hip and Groin Outcome Score (HAGOS). METHODS AND ANALYSIS: This trial is a single-blinded multicentre randomised controlled clinical trial, where patients with hip dysplasia, who are eligible for PAO, will be randomised to either PAO followed by usual care and PRT or PRT only. Primary outcome is patient-reported pain, measured on the subscale pain on the HAGOS questionnaire 12 months after initiation of PAO or PRT. The key secondary outcomes are the other subscales of the HAGOS, adverse and serious adverse events, usage of painkillers (yes/no) and type of analgesics. Based on the sample size calculation, the trial needs to include 96 patients. ETHICS AND DISSEMINATION: The trial is approved by the Central Denmark Region Committee on Biomedical Research Ethics (Journal No 1-10-72-234-18) and by the Danish Data Protection Agency (Journal No 1-16-02-120-19). The trial is also approved by The Regional Committee for Medical and Health Research Ethics, Region South-East Norway (Ref. 2018/1603). All results from this trial will be published in international peer-reviewed scientific journals regardless of whether the results are positive, negative or inconclusive. TRIAL REGISTRATION NUMBER: NCT03941171.

Are changes in pain associated with changes in quality of life and hip function 2 years after periacetabular osteotomy? A follow-up study of 321 patients.

Symptomatic hip dysplasia is primarily treated surgically with periacetabular osteotomy (PAO). It is unclear whether changes in quality of life (QoL) and changes in hip function follow the same pattern of improvement as pain following PAO. The aim of the study is to investigate whether changes in pain were associated with changes in QoL and hip function 2 years after PAO. Furthermore, to examine patient satisfaction 2 years after PAO. This is a follow-up study with data from Aarhus University Hospital Denmark. Pain was measured using the Visual Analogue Scale, QoL with Short-Form 36 and hip function with Hip disability and Osteoarthritis Outcome Score both preoperatively and 2 years after PAO in 321 patients. Multiple linear regressions were applied. Significant mean improvements in pain, QoL and hip function were found (P < 0.05). Significant associations between changes in pain and changes in physically related QoL and changes in hip function, respectively were found (P < 0.05). A non-significant association between changes in pain and changes in mentally- related QoL was found (P = 0.13). The majority of patients (84%) reported satisfaction with the result of PAO and would undergo PAO again if they had known the results in advance. The study had a loss to follow-up of 26%. Decreased pain was significantly associated with increased physically related QoL and improved hip function 2 years after PAO. A non-significant association between decreased pain and increased mentally related QoL was found. Patients were in general satisfied with treatment and results 2 years after PAO.

What level of pain reduction can be expected up to two years after periacetabular osteotomy? A prospective cohort study of 146 patients.

Periacetabular osteotomy (PAO) corrects underlying anatomical anomalies, reduces pain and may postpone or even prevent osteoarthritis onset in patients with symptomatic acetabular dysplasia. Current evidence is based on immediate post-operative pain levels, but knowledge on pain levels in the period after PAO is scarce, and the association between pain score and acetabular angles at PAO is unknown. This study had two aims. First, we studied pain level and patient-reported outcome scores pre- and postoperatively; second, we analysed the association between acetabular angles and pain level. From our database, 426 patients operated from June 2012 to November 2015 were analysed; 127 were excluded. Patients were invited to complete standardized questionnaires preoperatively and postoperatively at 6 and 24 months. Pain was measured using visual analogue scale (VAS). Multiple regression analysis was used to investigate the association between change in centre edge (CE) and acetabular index (AI) angle and pre/postoperative pain levels. Mean (standard deviation, SD) VAS pain at rest before surgery and at the 6- and 24-month follow-up were 35 (24), 14 (20) and 14 (19), respectively. Mean (SD) VAS pain at activity were 69 (22), 41 (29) and 41 (30), respectively. Both VAS pain at rest and at activity fell from the preoperative level to 6 months post-surgery with no further change at 24 months. Patients reported significant improvement in outcomes after 6 months and no further change at the 24-month follow-up. There was no significant association between change in CE/AI angles and VAS pain, either during rest or activity.

The interface between periacetabular osteotomy, hip arthroscopy and total hip arthroplasty in the young adult hip.

Hip pain is highly prevalent in both the younger and the elderly population. In older patients, pain arising from osteoarthritis (OA) is most frequent, whereas in younger patients, non-degenerative diseases are more often the cause of pain. The pain may be caused by hip dysplasia and femoroacetabular impingement (FAI).Abnormal mechanics of the hip are hypothesized by some authors to cause up to 80% of OA in the hip. Therefore, correction of these abnormalities is of obvious importance when treating young patients with hip pain.Hip dysplasia can be diagnosed by measuring a CE angle < 25° on a plain standing radiograph of the pelvis.Dysplastic or retroverted acetabulum with significant symptoms should receive a periacetabular osteotomy (PAO).FAI with significant symptoms should be treated by adequate resection and, if necessary, labrum surgery.If risk factors for poor outcome of joint-preserving surgery are present (age > 45 to 50 years, presence of OA, joint space < 3 mm or reduced range of motion), the patient should be offered a total hip arthroplasty (THA) instead of PAO.THA can be performed following PAO with outcomes similar to a primary THA.Hip arthroscopy is indicated in FAI (cam and pincer) and/or for labral tears. Cite this article: EFORT Open Rev 2018;3:408-417. DOI: 10.1302/2058-5241.3.170042.

Muscle-tendon-related abnormalities detected by ultrasonography are common in symptomatic hip dysplasia.

INTRODUCTION: Hip dysplasia is characterized by reduced acetabular coverage of the femoral head leading to an increased mechanical load on the hip joint and the acting hip muscles. Potentially, the muscles and tendons functioning close to the hip joint may present with overuse-related ultrasonography findings. The primary aim was to report the prevalence of muscle-tendon-related abnormalities detected by ultrasonography in 100 patients with symptomatic hip dysplasia. The secondary aim was to investigate correlations between muscle-tendon-related abnormalities detected by ultrasonography and clinically identified pain related to muscles and tendons. MATERIALS AND METHODS: One hundred patients (17 men) with a mean age of 29 ± 9 years were included. Muscle-tendon-related abnormalities were detected with a standardized ultrasound examination. Correlations between muscle-tendon-related abnormalities detected by ultrasonography and clinically identified pain related to muscles and tendons were tested with Spearman's rank correlation coefficient. RESULTS: The most prevalent ultrasonography findings were identified in the iliopsoas tendon [50% (95% CI 40; 60)], the adductor longus tendon [31% (95% 22; 40)] and the gluteus medius/minimus tendons [27% (18; 36)]. Significant correlations between ultrasonography findings and pain related to muscles and tendons were only found for the iliopsoas tendon (ρ = 0.24 and p = 0.02) and the gluteus medius/minimus tendons (ρ = 0.35 and p < 0.001). CONCLUSIONS: Muscle-tendon-related abnormalities detected by ultrasonography in the hip and groin region are common in patients with symptomatic hip dysplasia, and the ultrasonography findings of the iliopsoas and gluteus medius/minimus tendons are weakly to moderately correlated to pain related to muscles and tendons in these structures. Both the iliopsoas and the gluteus medius/minimus have a pronounced stabilizing role in the dysplastic hip joint, and the common muscle-tendon-related abnormalities in these patients may be caused by injuries related to excessive use or degenerative changes in the muscle-tendon tissue.

Higher Prevalence of Mixed or Solid Pseudotumors in Metal-on-Polyethylene Total Hip Arthroplasty Compared With Metal-on-Metal Total Hip Arthroplasty and Resurfacing Hip Arthroplasty.

BACKGROUND: Pseudotumors are a common finding in metal-on-metal (MoM) total hip arthroplasty (THA) and resurfacing hip arthroplasty (RHA). However, information on pseudotumors in metal-on-polyethylene (MoP) THA is limited. METHODS: One hundred eleven patients with 148 hip articulations-30 MoM THA, 47 MoM RHA, and 71 MoP THA-participated in a cross-sectional study at mean 7.1 (range: 0.2-21.5) years postoperatively. Patients were evaluated with metal artifact reducing sequence magnetic resonance imaging, measurements of metal ions, clinical scores of Harris Hip Score, Oxford Hip Score, the Copenhagen Hip and Groin Outcome Score, and conventional radiographs. RESULTS: Pseudotumors were present in 13 of 30 (43%) MoM THA, 13 of 47 (28%) MoM RHA, and 29 of 71 (41%) MoP THA patients, which was a similar prevalence (P = .10). The prevalence of mixed or solid pseudotumors was significantly higher in patients with MoP THA (n = 10) compared to MoM THA (n = 3) and MoM THA (n = 0), (P = .01). Hips with a mixed or solid pseudotumor had significantly poorer scores of Harris Hip Score (P = .01) and OHS (P = .002) and higher metal ion levels of cobalt (P = .0009) compared to hips without a pseudotumor or with a cystic pseudotumor. CONCLUSION: Pseudotumors have primarily been associated with MoM hip articulations, but we found a similar pseudotumor prevalence in MoP THA, which is the most common bearing worldwide. Mixed or solid pseudotumors were more often seen in MoP THA compared with MoM hip articulations, and patients with a mixed or solid pseudotumor had poorer clinical scores and higher metal ion levels than patients without a pseudotumor or with a cystic pseudotumor.