Aims. To investigate the optimal thresholds and diagnostic efficacy of commonly used serological and synovial fluid detection indexes for diagnosing periprosthetic joint infection (PJI) in patients who have rheumatoid arthritis (RA). Methods. The data from 348 patients who had RA or osteoarthritis (OA) and had previously undergone a total knee (TKA) and/or a total hip arthroplasty (THA) (including RA-PJI: 60 cases, RA-non-PJI: 80 cases; OA-PJI: 104 cases, OA-non-PJI: 104 cases) were retrospectively analyzed. A receiver operating characteristic curve was used to determine the optimal thresholds of the CRP, ESR, synovial fluid white blood cell count (WBC), and polymorphonuclear neutrophil percentage (PMN%) for diagnosing RA-PJI and OA-PJI. The diagnostic efficacy was evaluated by comparing the area under the curve (AUC) of each index and applying the results of the combined index diagnostic test. Results. For PJI prediction, the results of serological and synovial fluid indexes were different between the RA-PJI and OA-PJI groups. The optimal cutoff value of CRP for diagnosing RA-PJI was 12.5 mg/l, ESR was 39 mm/hour, synovial fluid WBC was 3,654/μl, and PMN% was 65.9%; and those of OA-PJI were 8.2 mg/l, 31 mm/hour, 2,673/μl, and 62.0%, respectively. In the RA-PJI group, the specificity (94.4%), positive predictive value (97.1%), and AUC (0.916) of synovial fluid WBC were higher than those of the other indexes. The optimal cutoff values of synovial fluid WBC and PMN% for diagnosing RA-PJI after THA were significantly higher than those of TKA. The specificity and positive predictive value of the combined index were 100%. Conclusion. Serum inflammatory and synovial fluid indexes can be used for diagnosing RA-PJI, for which synovial fluid WBC is the best detection index. Combining multiple detection indexes can provide a reference basis for the early and accurate diagnosis of RA-PJI. Cite this article: Bone Joint Res 2023;12(9):559–570

Aims. The Birmingham Hip Resurfacing (BHR) was introduced in 1997 to address the needs of young active patients using a historically proven large-diameter metal-on-metal (MoM) bearing. A single designer surgeon’s consecutive series of 130 patients (144 hips) was previously reported at five and ten years, reporting three and ten failures, respectively. The aim of this study was to extend the follow-up of this original cohort at 25 years. Methods. The study extends the reporting on the first consecutive 144 resurfacing procedures in 130 patients for all indications. All operations were undertaken between August 1997 and May 1998. The mean age at operation was 52.1 years (SD 9.93; 17 to 76), and included 37 female patients (28.5%). Failure was defined as revision of either component for any reason. Kaplan-Meier survival analysis was performed. Routine follow-up with serum metal ion levels, radiographs, and Oxford Hip Scores (OHSs) was undertaken. Results. Overall implant survival was 83.50% (95% confidence interval (CI) 0.79 to 0.90) at 25 years, and the number at risk was 79. Survival in male patients at 25 years was 89.5% (95% CI 0.83 to 0.96) compared to 66.9% for female patients (95% CI 0.51 to 0.83). Ten additional failures occurred in the period of ten to 25 years. These involved an adverse reaction to metal debris in four patients, a periprosthetic femoral neck fracture affecting five patients, and aseptic loosening in one patient. The median chromium levels were 49.50 nmol/l (interquartile range (IQR) 34 to 70), and the median cobalt serum levels were 42 nmol/l (IQR 24.50 to 71.25). The median OHS at last follow-up was 35 (IQR 10 to 48). During the 25-year study period, 29 patients died. Patient survival at 25 years was 75.10% (95% CI 0.67 to 0.83). Conclusion. This study demonstrates that MoM hip resurfacing using the BHR provides a durable alternative to total hip arthroplasty (THA), particularly in younger male patients with osteoarthritis wishing to maintain a high level of function. These results compare favourably to the best results for THAs. Cite this article: Bone Joint J 2024;106-B(6):540–547

In the differentiation of osteoclasts the differentiation factor (RANKL) interacts with the receptor activator of NF-κB (RANK) in a direct cell-to-cell contact between osteoblast and (pre)osteoclast. This is inhibited by soluble osteoprotegerin (OPG). The mRNA levels of both RANKL (p < 0.01) and RANK (p < 0.05) were high in peri-implant tissue and RANKL+ and RANK+ cells were found in such tissue. Double labelling also disclosed soluble RANKL bound to RANK+ cells. We were unable to stimulate fibroblasts to express RANKL in vitro, but monocyte activation with LPS gave a fivefold increase in RANK mRNA levels. In contrast to RANKL and RANK expression in peri-implant tissue, expression of OPG was restricted to vascular endothelium. Endothelial cell OPG mRNA levels were regulated by TNF-α and VEGF, but not by hypoxia. It is concluded that activated cells in the interface tissue overproduce both RANKL and RANK and they can interact without interference by OPG.

We report the use of porous metal acetabular revision shells in the treatment of contained bone loss. The outcomes of 53 patients with ≤ 50% acetabular bleeding host bone contact were compared with a control group of 49 patients with > 50% to 85% bleeding host bone contact. All patients were treated with the same type of trabecular metal acetabular revision shell. The mean age at revision was 62.4 years (42 to 80) and the mean follow-up of both groups was 72.4 months (60 to 102). Clinical, radiological and functional outcomes were assessed. There were four (7.5%) mechanical failures in the ≤ 50% host bone contact group and no failures in the > 50% host bone contact group (p = 0.068). Out of both groups combined there were four infections (3.9%) and five recurrent dislocations (4.9%) with a stable acetabular component construct that were revised to a constrained liner. Given the complexity of the reconstructive challenge, porous metal revision acetabular shells show acceptable failure rates at five to ten years’ follow-up in the setting of significant contained bone defects. This favourable outcome might be due to the improved initial stability achieved by a high coefficient of friction between the acetabular implant and the host bone, and the high porosity, which affords good bone ingrowth.

We collected 16 samples of the membrane which surrounds loose hip prostheses from patients undergoing revision operations for aseptic loosening. To serve as the control group, samples of the synovial tissue and the fibrous capsular tissue were collected from 11 patients undergoing primary hip arthroplasties. Analyses of the expression levels of inducible nitric oxide synthase (iNOS), tumour necrosis factor-α (TNF-α), and cytosolic phospholipase A₂ (cPLA₂) mRNAs were performed by a reverse transcription polymerase chain reaction, and the content of nitrite was measured by the Griess reaction using sodium nitrite as the standard.

The expression levels of iNOS, TNF-α, and cPLA₂ mRNAs in the membranes were significantly higher than those in the control samples (p < 0.05). The expression levels of iNOS mRNA and the nitrite content in the membranes significantly correlated with those of TNF-α and cPLA₂ mRNAs, respectively. In addition, the expression levels of iNOS, TNF-α, and cPLA₂ mRNAs were significantly higher in membranes from cementless than in those from cemented implants (p < 0.05).

Our results suggest that the expression levels of iNOS, TNF-α, and cPLA₂ mRNAs in the membranes are regulated by closely-related mechanisms and that these have a significant role in aseptic loosening.

We have investigated the use of a conically-shaped cement plug made of Polyactive (PA), a biodegradable copolymer. The flexibility and hydrogel properties were thought to facilitate occlusion of the femoral canal even when it was oval or irregular in shape. The function of the plug was first compared with that of the Thackray polyethylene model in 16 artificial plastic femora.

The maximum intramedullary pressure achieved during cementing was ten times higher with the biodegradable model. Migration or leakage of cement did not occur when the diameter of the femoral canal was equal to or smaller than the diameter of the plug. We also showed that the biodegradable properties of this implant were such that it did not require removal during revision.

The new plug was tested in a pilot clinical trial. At two years only two out of 21 patients had evidence of migration or leakage of cement, probably due to a mismatch in the size of plug and femoral canal. There were no local changes in the femur.

Aims. Total hip arthroplasty (THA) is one of the most successful surgical procedures. The objectives of this study were to define whether there is a correlation between socioeconomic status (SES) and surgical complications after elective primary unilateral THA, and investigate whether access to elective THA differs within SES groups. Methods. We conducted a retrospective, population-based cohort study involving 202 hospitals in Ontario, Canada, over a 17-year period. Patients were divided into income quintiles based on postal codes as a proxy for personal economic status. Multivariable logistic regression models were then used to primarily assess the relationship between SES and surgical complications within one year of index THA. Results. Of 111,359 patients who underwent elective primary THA, those in the lower SES groups had statistically significantly more comorbidities and statistically significantly more postoperative complications. While there was no increase in readmission rates within 90 days, there was a statistically significant difference in the primary and secondary outcomes including all revisions due (with a subset of deep wound infection and dislocation). Results showed that those in the higher SES groups had proportionally more cases performed than those in lower groups. Compared to the highest SES quintile, the lower groups had 61% of the number of hip arthroplasties performed. Conclusion. Patients in lower socioeconomic groups have more comorbidities, fewer absolute number of cases performed, have their procedures performed in lower-volume centres, and ultimately have higher rates of complications. This lack of access and higher rates of complications is a “double hit” to those in lower SES groups, and indicates that we should be concentrating efforts to improve access to surgeons and hospitals where arthroplasty is routinely performed in high numbers. Even in a universal healthcare system where there are no penalties for complications such as readmission, there seems to be an inequality in the access to THA. Cite this article: Bone Joint J 2022;104-B(5):589–597

From 1981 to 1983, we implanted Bioceram type-4 and type-5 prostheses in 61 hips in 54 patients with osteoarthritis secondary to acetabular dysplasia, congenital subluxation, or congenital dislocation of the hip. Fifty-seven hips in 50 patients were followed for a mean of 11.1 years (10 to 13). The mean age of the patients at operation was 53 years (31 to 70). Functional evaluation using the Merle d'Aubigne and Postel hip score showed a 77% success rate. Radiological loosening occurred in three femoral (5%) and 16 acetabular components (28%). Autologous femoral head grafts were used in 18 hips and became incorporated, giving mechanical support to the socket except for one which occupied a large weight-bearing area and eventually collapsed. The mean polyethylene wear was 1.1 mm (0 to 3.6) and the mean wear rate was 0.10 mm/year (0 to 0.31). A high rate of wear correlated with calcar resorption (p > 0.002) but not with acetabular loosening. There was no breakage of a ceramic head. Study of the ceramic heads and polyethylene sockets retrieved after ten years showed excellent surface roughness, sphericity, and bending strength for the heads but scratches and voids were seen on the sockets.

We studied 108 patients (116 hips) who were followed for a minimum of six years (73 to 89 months) after primary total hip arthroplasty using an uncemented porous-coated anatomic hip. The average age of the patients at operation was 48.4 years, and the diagnosis was avascular necrosis of the femoral head in 46 hips, neglected femoral neck fracture in 27, osteoarthritis secondary to childhood pyogenic arthritis in 24 and to childhood tuberculous arthritis in five, and miscellaneous in 14. The average preoperative Harris hip score was 55, which improved to 91 at latest follow-up. All patients with loose femoral components or disabling thigh pain had received prostheses which were undersized in the coronal or the sagittal plane, or in both. No patient with a satisfactory fit in both coronal and sagittal planes had loosening of the femoral component or disabling thigh pain. Three acetabular components showed aseptic loosening and 20 showed excessive wear (5 to 11 mm) of the polyethylene liner. Excessive wear was related to young age, but not to body-weight, gender, primary diagnosis, hip score, or range of hip movement. There was a high incidence of osteolysis (38 of 116 hips, 33%). We recommend careful preoperative planning, with the use of a contemporary cemented technique when a satisfactory fit cannot be obtained. The high incidence of excessive wear and of osteolysis needs further investigation.

Total arthroplasty was performed on 21 congenitally dislocated hips in 18 women. In all cases the femoral head was dislocated cranially at least one-fifth of the height of the pelvis. The components were both cemented, the acetabulum being replaced to its original position. The acetabular roof was reconstructed by bone graft in 13 hips, and trochanteric osteotomy was done in 18 hips. The patients were assessed at a median follow-up time of 7.5 years when their median age was 54 years. Nine patients had been revised or required revision. At follow-up the average functional score (according to Charnley) was 6 for pain, 4 for walking ability and 5 for range of motion. The Harris hip score was 82. The patients' subjective evaluation of their satisfaction with the late results on a visual analogue scale was 93, range 23 to 100. The high loosening rate in such patients demands regular follow-up and preparedness for revision surgery.

Aims. Instability is a common cause of failure after total hip arthroplasty. A novel reverse total hip has been developed, with a femoral cup and acetabular ball, creating enhanced mechanical stability. The purpose of this study was to assess the implant fixation using radiostereometric analysis (RSA), and the clinical safety and efficacy of this novel design. Methods. Patients with end-stage osteoarthritis were enrolled in a prospective cohort at a single centre. The cohort consisted of 11 females and 11 males with mean age of 70.6 years (SD 3.5) and BMI of 31.0 kg/m. 2. (SD 5.7). Implant fixation was evaluated using RSA as well as Western Ontario and McMaster Universities Osteoarthritis Index, Harris Hip Score, Oxford Hip Score, Hip disability and Osteoarthritis Outcome Score, 38-item Short Form survey, and EuroQol five-dimension health questionnaire scores at two-year follow-up. At least one acetabular screw was used in all cases. RSA markers were inserted into the innominate bone and proximal femur with imaging at six weeks (baseline) and six, 12, and 24 months. Independent-samples t-tests were used to compare to published thresholds. Results. Mean acetabular subsidence from baseline to 24 months was 0.087 mm (SD 0.152), below the critical threshold of 0.2 mm (p = 0.005). Mean femoral subsidence from baseline to 24 months was -0.002 mm (SD 0.194), below the published reference of 0.5 mm (p < 0.001). There was significant improvement in patient-reported outcome measures at 24 months with good to excellent results. Conclusion. RSA analysis demonstrates excellent fixation with a predicted low risk of revision at ten years of this novel reverse total hip system. Clinical outcomes were consistent with safe and effective hip replacement prostheses. Cite this article: Bone Jt Open 2023;4(5):385–392

Aims. The risk factors for abnormal spinopelvic mobility (SPM), defined as an anterior rotation of the spinopelvic tilt (∆SPT) ≥ 20° in a flexed-seated position, have been described. The implication of pelvic incidence (PI) is unclear, and the concept of lumbar lordosis (LL) based on anatomical limits may be erroneous. The distribution of LL, including a unusual shape in patients with a high lordosis, a low pelvic incidence, and an anteverted pelvis seems more relevant. Methods. The clinical data of 311 consecutive patients who underwent total hip arthroplasty was retrospectively analyzed. We analyzed the different types of lumbar shapes that can present in patients to identify their potential associations with abnormal pelvic mobility, and we analyzed the potential risk factors associated with a ∆SPT ≥ 20° in the overall population. Results. ΔSPT ≥ 20° rates were 28.3%, 11.8%, and 14.3% for patients whose spine shape was low PI/low lordosis (group 1), low PI anteverted (group 2), and high PI/high lordosis (group 3), respectively (p = 0.034). There was no association between ΔSPT ≥ 20° and PI ≤ 41° (odds ratio (OR) 2.01 (95% confidence interval (CI)0.88 to 4.62), p = 0.136). In the multivariate analysis, the following independent predictors of ΔSPT ≥ 20° were identified: SPT ≤ -10° (OR 3.49 (95% CI 1.59 to 7.66), p = 0.002), IP-LL ≥ 20 (OR 4.38 (95% CI 1.16 to 16.48), p = 0.029), and group 1 (OR 2.47 (95% CI 1.19; to 5.09), p = 0.0148). Conclusion. If the PI value alone is not indicative of SPM, patients with a low PI, low lordosis and a lumbar apex at L4-L5 or below will have higher rates of abnormal SPM than patients with a low PI anteverted and high lordosis. Cite this article: Bone Jt Open 2023;4(9):668–675

The Wroblewski golf ball acetabular cup was introduced by surgeons using the trochanteric osteotomy approach for revision total hip replacement (THR) in order to reduce the rate of dislocation. We have routinely used the Ogee long posterior wall (Ogee LPW) and the Wroblewski angle bore cups in THR. Although the new Wroblewski golf ball cup performed well there was a significant early rate of dislocation of 20%. Our rate of dislocation over a period of ten years using the Ogee LPW and Wroblewski angle bore cups had been 0.52%. We present our findings and an investigation as to why the new cup has such a high rate of dislocation when used with the posterior approach. We show that a relatively small change in the design of the acetabular component resulted in significant adverse clinical results.

Aims. The impact of a diaphyseal femoral deformity on knee alignment varies according to its severity and localization. The aims of this study were to determine a method of assessing the impact of diaphyseal femoral deformities on knee alignment for the varus knee, and to evaluate the reliability and the reproducibility of this method in a large cohort of osteoarthritic patients. Methods. All patients who underwent a knee arthroplasty from 2019 to 2021 were included. Exclusion criteria were genu valgus, flexion contracture (> 5°), previous femoral osteotomy or fracture, total hip arthroplasty, and femoral rotational disorder. A total of 205 patients met the inclusion criteria. The mean age was 62.2 years (SD 8.4). The mean BMI was 33.1 kg/m. 2. (SD 5.5). The radiological measurements were performed twice by two independent reviewers, and included hip knee ankle (HKA) angle, mechanical medial distal femoral angle (mMDFA), anatomical medial distal femoral angle (aMDFA), femoral neck shaft angle (NSA), femoral bowing angle (FBow), the distance between the knee centre and the top of the FBow (DK), and the angle representing the FBow impact on the knee (C’KS angle). Results. The FBow impact on the mMDFA can be measured by the C’KS angle. The C’KS angle took the localization (length DK) and the importance (FBow angle) of the FBow into consideration. The mean FBow angle was 4.4° (SD 2.4; 0 to 12.5). The mean C’KS angle was 1.8° (SD 1.1; 0 to 5.8). Overall, 84 knees (41%) had a severe FBow (> 5°). The radiological measurements showed very good to excellent intraobserver and interobserver agreements. The C’KS increased significantly when the length DK decreased and the FBow angle increased (p < 0.001). Conclusion. The impact of the diaphyseal femoral deformity on the mechanical femoral axis is measured by the C’KS angle, a reliable and reproducible measurement. Cite this article: Bone Jt Open 2023;4(4):262–272

Aims. Periacetabular osteotomy (PAO) is the preferred treatment for symptomatic acetabular dysplasia in adolescents and young adults. There remains a lack of consensus regarding whether intra-articular procedures such as labral repair or improvement of femoral offset should be performed at the time of PAO or addressed subsequent to PAO if symptoms warrant. The purpose was to determine the rate of subsequent hip arthroscopy (HA) in a contemporary cohort of patients, who underwent PAO in isolation without any intra-articular procedures. Methods. From June 2012 to March 2022, 349 rectus-sparing PAOs were performed and followed for a minimum of one year (mean 6.2 years (1 to 11)). The mean age was 24 years (14 to 46) and 88.8% were female (n = 310). Patients were evaluated at final follow-up for patient-reported outcome measures (PROMs). Clinical records were reviewed for complications or subsequent surgery. Radiographs were reviewed for the following acetabular parameters: lateral centre-edge angle, anterior centre-edge angle, acetabular index, and the alpha-angle (AA). Patients were cross-referenced from the two largest hospital systems in our area to determine if subsequent HA was performed. Descriptive statistics were used to analyze risk factors for HA. Results. A total of 16 hips (15 patients; 4.6%) underwent subsequent HA with labral repair and femoral osteochondroplasty, the most common interventions. For those with a minimum of two years of follow-up, 5.3% (n = 14) underwent subsequent HA. No hips underwent total hip arthroplasty and one revision PAO was performed. Overall, 17 hips (4.9%) experienced a complication and 99 (26.9%) underwent hardware removal. All PROMs improved significantly postoperatively. Radiologically, 80% of hips (n = 279) reached the goal for acetabular correction (77% for acetbular index and 93% for LCEA), with no significant differences between those who underwent subsequent HA and those who did not. Conclusion. Rectus-sparing PAO is associated with a low rate of subsequent HA for intra-articular pathology at a mean of 6.2 years’ follow-up (1 to 11). Acetabular correction alone may be sufficient as the primary intervention for the majority of patients with symptomatic acetabular dysplasia. Cite this article: Bone Joint J 2024;106-B(5 Supple B):17–24

Aims. Periprosthetic proximal femoral fractures (PFFs) are a major complication after total hip arthroplasty (THA). Health status after PFF is not specifically investigated. The aim of this study is to evaluate the health status pattern over two years after sustaining a PFF. Methods. A cohort of patients with PFF after THA was derived from the Brabant Injury Outcomes Surveillance (BIOS) study. The BIOS study, a prospective, observational, multicentre follow-up cohort study, was conducted to obtain data by questionnaires pre-injury and at one week, and one, three, six, 12, and 24 months after trauma. Primary outcome measures were the EuroQol five-dimension three-level questionnaire (EQ-5D-3L), the Health Utility Index 2 (HUI2), and the Health Utility Index 3 (HUI3). Secondary outcome measures were general measurements such as duration of hospital stay and mortality. Results. A total of 70 patients with a PFF were included. EQ-5D utility scores were significantly lower on all timepoints except at six months’ follow-up compared to pre-injury. EuroQol visual analogue scale (EQ-VAS) scores at one month's follow-up were significantly lower compared to pre-injury. The percentage of reported problems at two years was higher for all dimensions except anxiety/depression when compared to pre-injury. The mean EQ-5D utility score was 0.26 higher in males compared to females (95% confidence interval (CI) 0.01 to 0.42; p = 0.003). The mean EQ-VAS score for males was 8.9 points higher when compared to females over all timepoints (95% CI 1.2 to 16.7; p = 0.027). Mortality was 10% after two years’ follow-up. Conclusion. PFF patients are a frail population with substantial functional impairment at baseline. Post-injury, they have a significant and clinically relevant lower health status two years after trauma when compared to pre-injury. Health status improves the most between one and three months after injury. Two years after PFF, more patients experience problems in mobility, self-care, usual activities, and pain/discomfort than pre-injury. Cite this article: Bone Joint J 2024;106-B(5):442–449

Between April 1992 and July 2005, 310 posterior lip augmentation devices were used for the treatment of recurrent dislocation of the hip in 307 patients who had received primary total hip replacements (THRs) using Charnley/Charnley Elite components with a cemented acetabulum. The mean number of dislocations before stabilisation with the device was five (1 to 16) with a mean time to this intervention from the first dislocation of 3.8 years (0 days to 22.5 years). The mean age of the patients at this reconstruction was 75.4 years (39 to 96).

A retrospective clinical and radiological review was carried out at a mean follow-up of six years and nine months (4.4 months to 13 years and 7 months). Of the 307 patients, 53 had died at the time of the latest review, with a functioning THR and with the posterior lip augmentation device in situ. There were four revisions (1.3%), one for pain, two for deep infection and one for loosening of the acetabular component. Radiolucent lines around the acetabular component increased in only six cases after insertion of the device which was successful in eliminating instability in 302 patients, with only five further dislocations (1.6%) occurring after its insertion.