Topic. Utilizing radiographic, physical exam and history findings, we developed a novel clinical score to aid in the surgical decision making process for hips with borderline/ transitional dysplastic hips. Background. Treatment of borderline acetabular dysplasia (BD) is controversial with some patients having primarily instability-based symptoms while others have impingement-based symptoms. The purpose of this study was to identify the most important patient characteristics influencing the diagnosis of instability vs. non-instability, develop a clinical score (Borderline Hip Instability Score, BHIS) to collectively characterize these factors and to externally validate BHIS in a multicenter cohort BD patients. Methods. First a retrospective cohort of 186 hips undergoing surgical treatment of BD (LCEA 20°-25°) from a single surgeon experienced in arthroscopic and open techniques was used. Multivariate analysis determined characteristics associated with presence of instability (PAO+/−hip arthroscopy) or absence of instability (isolated hip arthroscopy) based on clinical diagnosis. During the study period, 39.8% of the cohort underwent PAO. Multivariate analysis with bootstrapping was performed and results were transformed into a BHIS nomogram (higher score representing more instability). Then, BHIS was externally validated in 114 BD patients enrolled in a multicenter prospective cohort study across 10 surgeons (with varied treatment approaches from arthroscopy to open procedures). Results. The most parsimonious, best fit model included 4 variables associated with the diagnosis of instability: acetabular inclination (AI), anterior center edge angle (ACEA), maximum alpha angle, and internal rotation in 90 degrees of flexion (IRF). Sex and LCEA were not significant predictors. Mean BHIS in the population was 50.0 (instability 57.7 ±7.9; non-instability 44.8±7.3, p<0.001). BHIS demonstrated excellent predictive (discriminatory) ability with c-statistic=0.89. In Part 2, BHIS maintained excellent c-statistic=0.92 in external validation. Mean BHIS in the external cohort was 53.9 (instability 66.5±11.5; non-instability 43.0±10.8, p<0.001). Discussion. In patients with BD, key factors in diagnosing significant instability treated with PAO were AI, ACEA, maximum alpha-angle, and IRF. The BHIS score allowed for differentiation of patients with and without instability in the development and external validation cohort. For any tables or figures, please contact the authors directly

Serum and blood cobalt (Co) and chromium (Cr) ion levels are used to monitor patients at risk for adverse reaction to metal debris (ARMD) following metal-on-metal (MoM) total hip arthroplasty (THA). However, these levels often do not correlate with the degree of local soft-tissue reaction and damage observed at the time of revision. The purpose of this study was to analyze synovial fluid metal ion concentrations in patients with a failed THA in the setting of an ARMD and determine if these levels can be more predictive of soft-tissue destruction than serum or whole blood levels. Synovial, blood and serum samples were prospectively collected from patients undergoing revision THA with ARMD (n=29) and those undergoing aseptic revision without ARMD (n=29). There was no difference in mean age (P=0.50), BMI (P=0.18), sex distribution (P=0.18), serum creatinine (P=0.74), or time to revision THA (P=0.13) between the cohorts. In the AMRD cohort, the components included MoM THA (n=18), hip resurfacing (n=5), dual-modular taper THA (n=4) and MoM and dual-modular taper THA (n=2). At the time of revision THA, 26 (90%) patients in the metal reaction cohort had gross evidence of metallosis in the soft-tissues, the remaining 3 (10%) had evidence of corrosion of the dual taper neck or MoM bearing. In the non ARMD cohort the bearing surfaces included metal-on-polyethylene (n=19) and ceramic-on-polyethylene (n=10). The indications for revision included isolated acetabular loosening (n=11), isolated femoral component loosening (n=11), polyethylene wear (n=5), recurrent dislocation (n=1) and combined femoral and acetabular component loosening (n=1). None had a clinical diagnosis or gross evidence of taper corrosion. Pre-revision, 21 (72%) patients in the metal reaction group had periarticular fluid collections or a mass on MRI. Mean cyst size was 202.9±71.6 cm3 and masses were grouped into Type I (cyst wall <3 mm, n=10), Type II (cyst wall ≥3 mm, n=8) and Type III (mainly solid, n=3). At the time of revision THA, the mean Co levels were elevated in patients with ARMD compared to those without in synovial fluid (1,833 ppb vs. 12.3 ppb, P=0.008), whole blood (22.6 ppb vs 0.5 ppb, P=0.005)) and serum (19.6 vs. 0.6, P=0.001). Likewise, mean Cr levels were significantly elevated in patients with an ARMD compared to those undergoing revision without in synovial fluid (3,128 ppb vs. 10.3 ppb, P=0.01), whole blood (8.9 ppb vs. 0.5 ppb, P=0.009) and serum (14.1 ppb vs. 0.5 ppb, P=0.005). The synovial fluid Co levels were the most accurate test for detecting pseudotumor (AUC 0.951) and adverse local tissue reaction (AUC 0.826). At a synovial fluid Cr level of 110 ppb, the synovial fluid metal ion analysis was 94% sensitive and 86% specific for pseudotumor formation. In this prospective study, synovial fluid analysis of metal ion levels was more accurate in predicting the presence and extent of pseudo-tumor or ALTR compared to blood or serum analysis. The addition of synovial aspiration with metal ion analysis may provide another helpful data point when risk stratifying these patients for need for revision THA

Total hip replacement (THR) is a very common procedure undertaken in up to 285 000 Americans each year. Patient satisfaction with THR is very high, with improvements in general health, quality of life, and function while at the same time very cost effective. Although the majority of patients have a high degree of satisfaction with their THR, 27% experience some discomfort, and up to 6% experience severe chronic pain. Although it can be difficult to diagnose the cause of the pain in these patients, this clinical issue should be approached systematically and thoroughly. A detailed history and clinical examination can often provide the correct diagnosis and guide the appropriate selection of investigations, which will then serve to confirm the clinical diagnosis made. . Cite this article: Bone Joint J 2013;95-B, Supple A:70–3

Aims

Some patients presenting with hip pain and instability and underlying acetabular dysplasia (AD) do not experience resolution of symptoms after surgical management. Hip-spine syndrome is a possible underlying cause. We hypothesized that there is a higher frequency of radiological spine anomalies in patients with AD. We also assessed the relationship between radiological severity of AD and frequency of spine anomalies.

Aims

Total hip arthroplasty (THA) patients undergoing or having a prior lumbar spine fusion (LSF) have an increased risk of mechanical complications. The aim of this registry-based, retrospective comparative cohort study is to assess the longer term survival of THA in patients who have undergone a LSF during a 17-year period (2000 to 2017).

Aims

Advances in surgical technique and implant design may influence the incidence and mechanism of failure resulting in revision total hip arthroplasty (rTHA). The purpose of the current study was to characterize aetiologies requiring rTHA, and to determine whether temporal changes existed in these aetiologies over a ten-year period.

Aims

The prevalence of combined abnormalities of femoral torsion (FT) and tibial torsion (TT) is unknown in patients with femoroacetabular impingement (FAI) and hip dysplasia. This study aimed to determine the prevalence of combined abnormalities of FT and TT, and which subgroups are associated with combined abnormalities of FT and TT.

Aims

The aim of this study was to identify modifiable risk factors associated with mortality in patients requiring revision total hip arthroplasty (THA) for periprosthetic hip fracture.

Aims

Abnormal femoral torsion (FT) is increasingly recognized as an additional cause for femoroacetabular impingement (FAI). It is unknown if in-toeing of the foot is a specific diagnostic sign for increased FT in patients with symptomatic FAI. The aims of this study were to determine: 1) the prevalence and diagnostic accuracy of in-toeing to detect increased FT; 2) if foot progression angle (FPA) and tibial torsion (TT) are different among patients with abnormal FT; and 3) if FPA correlates with FT.

As adverse events related to metal on metal hip arthroplasty have been better understood, there has been increased interest in toxicity related to the high circulating levels of cobalt ions. However, distinguishing true toxicity from benign elevations in cobalt levels can be challenging. The purpose of this review is to examine the use of cobalt alloys in total hip arthroplasty, to review the methods of measuring circulating cobalt levels, to define a level of cobalt which is considered pathological and to review the pathophysiology, risk factors and treatment of cobalt toxicity. To the best of our knowledge, there are 18 published cases where cobalt metal ion toxicity has been attributed to the use of cobalt-chromium alloys in hip arthroplasty. Of these cases, the great majority reported systemic toxic reactions at serum cobalt levels more than 100 μg/L. This review highlights some of the clinical features of cobalt toxicity, with the goal that early awareness may decrease the risk factors for the development of cobalt toxicity and/or reduce its severity.

Take home message: Severe adverse events can arise from the release of cobalt from metal-on-metal arthroplasties, and as such, orthopaedic surgeons should not only be aware of the presenting problems, but also have the knowledge to treat appropriately.

Cite this article: Bone Joint J 2016;98-B:14–20.

Femoroacetabular impingement causes pain in the hip in young adults and may predispose to the development of osteoarthritis. Genetic factors are important in the aetiology of osteoarthritis of the hip and may have a role in that of femoroacetabular impingement. We compared 96 siblings of 64 patients treated for primary impingement with a spouse control group of 77 individuals. All the subjects were screened clinically and radiologically using a standardised protocol for the presence of cam and pincer deformities and osteoarthritis.

The siblings of those patients with a cam deformity had a relative risk of 2.8 of having the same deformity (66 of 160 siblings hips versus 23 of 154 control hips, p < 0.00001). The siblings of those patients with a pincer deformity had a relative risk of 2.0 of having the same deformity (43 of 116 sibling hips versus 29 of 154 control hips, p = 0.001). Bilateral deformity occurred more often in the siblings (42 of 96 siblings versus 13 of 77 control subjects, relative risk 2.6, p = 0.0002). The prevalence of clinical features in those hips with abnormal morphology was also greater in the sibling group compared with the control group (41 of 109 sibling hips versus 7 of 46 control hips, relative risk 2.5, p = 0.007). In 11 sibling hips there was grade-2 osteoarthritis according to Kellgren and Lawrence versus none in the control group (p = 0.002).

Genetic influences are important in the aetiology of primary femoroacetabular impingement. This risk appears to be manifested through not only abnormal joint morphology, but also through other factors which may modulate progression of the disease.

Sciatic nerve palsy is a recognised complication of primary total hip replacement. In our unit this complication was rare with an incidence of < 0.2% in the past ten years. We describe six cases of sciatic nerve palsy occurring in 355 consecutive primary total hip replacements (incidence 1.69%). Each of these palsies was caused by post-operative haematoma in the region of the sciatic nerve.

Cases, which were recognised early and surgically-evacuated promptly, showed earlier and more complete recovery. Those patients for whom the diagnosis was delayed, and who were therefore managed expectantly, showed little or no recovery. Unexpected pain and significant swelling in the buttock, as well as signs of sciatic nerve irritation, suggest the presence of haematoma in the region of the sciatic nerve.

It is, therefore, of prime importance to be vigilant for the features of a sciatic nerve palsy in the early post-operative period as, when recognised and treated early, the injury to the sciatic nerve may be reversed.