Osteoclasts in Periprosthetic Osteolysis: The Charnley Arthroplasty Revisited.

BACKGROUND: Periprosthetic osteolysis by polyethylene wear debris-triggered osteoclasts is viewed as the main pathophysiological pathway in aseptic loosening in total hip arthroplasty. The present aim was to study osteoclast occurrence in osteolytic lesions in early and late revisions of the Charnley low-friction torque arthroplasty (CLFA). METHODS: Biopsies of the soft interface membrane and the adjacent bone were taken from osteolytic lesions during revision of 16 loose CLFA, early (2-6 years) or late (>10 years) after primary surgery. By light microscopy (LM), cell-dense regions with signs of osteoclast-mediated bone resorption were selected for transmission electron microscopy. Three additional patients were studied in LM for osteoclast markers (tartrate-resistant acid phosphatase and Cathepsin K). RESULTS: LM disclosed a low-grade chronic inflammation and birefringent particles in most sections. Multiple conglomerates of tartrate-resistant acid phosphatase positive and Cathepsin K positive mononuclear and multinucleated cells were found deep in the fibrous interface membrane. Transmission electron microscopy showed traces of polyethylene-like particles in 67%-100% of the cells. Osteoclast-like cells exhibiting resorptive activity were few (mean, 0.7%; standard deviation, 0.2%), and multinucleated cells, possibly osteoclast precursor cells, located immediately on the bone were also scarce (mean, 2.7%; standard deviation, 5.3%). Multinucleated (odds ratio, 3.0; 95% confidence interval, 1.7-5.5) and macrophage-like cells (odds ratio, 3.6; 95% confidence interval, 2.2-5.6) were typically located deeper in the inflammatory interface membrane with a pathologic appearance with distension and abundance of phagocytic vacuoles. There were no systematic differences in cell populations between early or late revisions. CONCLUSION: Despite probable ongoing osteoclastogenesis in the osteolytic lesions, there were few sites of osteoclast-mediated bone resorption. These findings attach a contributing biological explanation to the longevity of the CLFA.

Association between changes in global femoral offset after total hip arthroplasty and function, quality of life, and abductor muscle strength. A prospective cohort study of 222 patients.

BACKGROUND AND PURPOSE: There is no consensus on the association between global femoral offset (FO) and outcome after total hip arthroplasty (THA). We assessed the association between FO and patients' reported hip function, quality of life, and abductor muscle strength. PATIENTS AND METHODS: We included 250 patients with unilateral hip osteoarthritis who underwent a THA. Before the operation, the patient's reported hip function was evaluated with the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index and quality of life was evaluated with EQ-5D. At 1-year follow-up, the same scores and also hip abductor muscle strength were measured. 222 patients were available for follow-up. These patients were divided into 3 groups according to the postoperative global FO of the operated hip compared to the contralateral hip, as measured on plain radiographs: the decreased FO group (more than 5 mm reduction), the restored FO group (within 5 mm restoration), and the increased FO group (more than 5 mm increment). RESULTS: All 3 groups improved (p < 0.001). The crude results showed that the decreased FO group had a worse WOMAC index, less abductor muscle strength, and more use of walking aids. When we adjusted these results with possible confounding factors, only global FO reduction was statistically significantly associated with reduced abductor muscle strength. The incidence of residual hip pain and analgesics use was similar in the 3 groups. INTERPRETATION: A reduction in global FO of more than 5 mm after THA appears to have a negative association with abductor muscle strength of the operated hip, and should therefore be avoided.

Validity, reliability and reproducibility of plain radiographic measurements after total hip arthroplasty.

BACKGROUND: In total hip arthroplasty (THA), radiographic preoperative planning and postoperative evaluation of acetabular component, femoral offset (FO) and leg length discrepancy (LLD) require good validity, interobserver reliability and intraobserver reproducibility. In this study, we evaluated the validity of the Sundsvall method of FO measurement and the interobserver reliability and intraobserver reproducibility of measurement of FO, LLD, acetabular cup inclination and anteversion. MATERIAL AND METHODS: Ninety patients with primary unilateral osteoarthritis (OA) were included in this prospective study. On postoperative radiographs FO by the Sundsvall method (femoral axis-pelvic midline), FO by a standard method (femoral axis-hip rotational centre-teardrop point), LLD (inter-teardrop line-lesser trochanter), acetabular cup inclination (on AP view the angle between the cup rim and transischial line) and anteversion (on lateral view the angle between the face of acetabulum and a line perpendicular to the horizontal plane) were measured. The interobserver reliability and intraobserver reproducibility were calculated for three independent observers. The concurrent validity and degree of prediction of the Sundsvall method are measured by comparing its results with the standard method. RESULTS: The interobserver reliability of all measurements was excellent (ICC >0.80), except for LLD, which was substantial (ICC = 0.79). The intraobserver reproducibility of all measurements was excellent (ICC > 0.80). The concurrent validity of the Sundsvall method compared to the standard method was good with a positive correlation. CONCLUSION: The Sundsvall method is as reliable as the standard method. The evaluated radiographic measurement methods have the required validity and reliability to be used in clinical practice.

The Influence of Leg Length Discrepancy after Total Hip Arthroplasty on Function and Quality of Life: A Prospective Cohort Study.

We investigated whether patients with lengthening (> 9 mm), restoration (between 9 mm lengthening and 5 mm shortening) or shortening (> 5 mm) of the operated leg after total hip arthroplasty (THA) had different function (WOMAC score), quality of life (EQ-5D), residual hip pain, use of shoe lift and walking aid and leg length discrepancy (LLD) awareness, 12-15 months postoperatively. All patients had a significant postoperative improvement in WOMAC and EQ-5D regardless the LLD. However, the lengthening group showed less improvement in WOMAC, more use of shoe lift, residual hip pain and LLD awareness compared with the other two groups. No differences in EQ-5D were found. In spite of the improvement in function and quality of life, lengthening had adverse effects and should therefore be avoided.

The experience of nurse anaesthetists in assessing postoperative pain in orthopaedic patients.

Aim To explore the experiences of anaesthesia nurses in assessing postoperative pain in patients undergoing total hip and/or knee arthroplasty. Methods Data were collected through four focus group interviews (FGI) using the critical incident technique (CIT). The participants were six men and 12 women, all registered nurses with further education in anaesthesia with at least five-year experience of caring for patients on a postoperative ward. Results Maintaining communication with orthopaedic patients, different ways to assess pain, the assessment of unresponsive patients, using pain assessment scales and different work circumstances influencing their use, were stated as the main problems the nurses emphasize while assessing the pain of patients. Conclusion Skills related to observing the behaviour and experience of pain in different individuals are needed to ensure an understanding of patients' pain, as well as the patients' ability to estimate their pain, where the intensity of the pain varies in different patients. Further studies are needed to examine the way health professionals assess pain, depending on the patients' ability to transform their pain from a subjective feeling into an objective numeric grade. The way individuals assess their pain differently and the way the resulting knowledge and experience of postoperative care may help nurses and other health-care professionals.

A randomized double-blind noninferiority trial, evaluating migration of a cemented vitamin E-stabilized highly crosslinked component compared with a standard polyethylene component in reverse hybrid total hip arthroplasty.

AIMS: Radiostereometric analysis (RSA) studies of vitamin E-doped, highly crosslinked polyethylene (VEPE) liners show low head penetration rates in cementless acetabular components. There is, however, currently no data on cemented VEPE acetabular components in total hip arthroplasty (THA). The aim of this study was to evaluate the safety of a new cemented VEPE component, compared with a conventional polyethylene (PE) component regarding migration, head penetration, and clinical results. PATIENTS AND METHODS: We enrolled 42 patients (21 male, 21 female) with osteoarthritis and a mean age of 67 years (sd 5), in a double-blinded, noninferiority, randomized controlled trial. The subjects were randomized in a 1:1 ratio to receive a reverse hybrid THA with a cemented component of either argon-gas gamma-sterilized PE component (controls) or VEPE, with identical geometry. The primary endpoint was proximal implant migration of the component at two years postoperatively measured with RSA. Secondary endpoints included total migration of the component, penetration of the femoral head into the component, and patient-reported outcome measurements. RESULTS: In total, 19 control implants and 18 implants in the VEPE group were analyzed for the primary endpoint. We found a continuous proximal migration of the component in the VEPE group that was significantly higher with a difference at two years of a mean 0.21 mm (95% confidence interval (CI) 0.05 to 0.37; p = 0.013). The total migration was also significantly higher in the VEPE group, but femoral head penetration was lower. We found no difference in clinical outcomes between the groups. CONCLUSION: At two years, this cemented VEPE component, although having a low head penetration and excellent clinical results, failed to meet noninferiority compared with the conventional implant by a proximal migration above the proposed safety threshold of RSA. The early proximal migration pattern of the VEPE component is a reason for continued monitoring, although a specific threshold for proximal migration and risk for later failure cannot be defined and needs further study. Cite this article: Bone Joint J 2019;101-B:1192-1198.

Abductor Muscle Function and Trochanteric Tenderness After Hemiarthroplasty for Femoral Neck Fracture.

OBJECTIVES: To compare the abductor muscle function and trochanteric tenderness in patients operated with hemiarthroplasty using the direct lateral (DL) or posterolateral (PL) approach for displaced femoral neck fracture. DESIGN: Prospective cohort study. SETTING: A secondary teaching hospital. PARTICIPANTS: We enrolled 183 hips operated with hemiarthroplasty for displaced femoral neck fracture using the DL or PL approach. INTERVENTIONS: Preoperatively, we evaluated the Harris hip score (HHS) and European Quality of Life-5 Dimensions (EQ-5D). At 1 year postoperatively, lucid patients were clinically examined to evaluate the Trendelenburg sign, abductor muscle strength with a dynamometer, and trochanteric tenderness with an electronic algometer. The 1-year HHS and EQ-5D were documented. MAIN OUTCOME MEASURES: The primary outcome was the incidence of postoperative Trendelenburg sign, whereas the secondary outcomes included patients' reported limp, abductor muscle strength, trochanteric tenderness, HHS, and EQ-5D. RESULTS: There were 48 patients (24 in the DL group and 24 in the PL group) who attended the 1-year clinical follow-up. The 2 groups were comparable (P > 0.05). The DL group showed a higher incidence of the Trendelenburg sign (9/24 vs. 1/24, P = 0.02) and limp (12/24 vs. 2/24, P = 0.004). Further analysis with logistic regression showed the surgical approach to be the only factor that resulted in the increment. No differences regarding HHS, EQ-5D, abductor muscle strength, algometer pressure pain threshold, and radiologic measurements were found (P > 0.05). CONCLUSIONS: The incidence of the Trendelenburg sign and limp were significantly higher in the DL approach although this seemed not to influence abductor muscle strength or the incidence of trochanteric tenderness or compromise the clinical outcome. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Debridement, antibiotics and implant retention in early periprosthetic joint infection.

INTRODUCTION: Periprosthetic joint infection (PJI) is a devastating complication in hip arthroplasty surgery. Debridement, antibiotics (AB) and implant retention (DAIR) is recommended in early PJI in association with stable implants. The aim of this study was to evaluate the success rate of DAIR in early PJI (<4 weeks) and to identify factors predicting the outcome. METHODS: This cohort study included a consecutive series of 35 patients (median age 74 years, 25 women, 26 primary arthroplasties) treated with DAIR for an early PJI in a regional hospital. RESULTS: 28 patients (80%) had their infection eradicated. DAIR-only eradicated the PJI in 22 (63%) patients with a median follow-up of 50 (24-84) months. In 17 (49%) patients, oral AB had been given prior to intraoperative cultures, which delayed first debridement with average 6 days and delayed hospital stay. Primary surgery for a hip fracture increased the risk of DAIR-failure. Surgical experience did not affect the outcome. 17% (n = 6) of the patients sustained a secondary infection during their hospital stay; the majority was beta-lactam resistant coagulase negative Staphylococcus aureus. CONCLUSIONS: The success rate of DAIR was inferior to pervious controls from experienced revision centers. Hip fracture patients should be informed about the increased risk of DAIR treatment failure. In order not to delay surgery, empirically based oral AB should not be administered prior to deep cultures. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02087020.

An update on surgical approaches in hip arthoplasty: lateral versus posterior approach.

In this update we searched the literature about the outcome of the lateral versus posterior approach in hip arthoplasty for osteoarthritis (OA) and femoral neck fracture (FNF) patients. The available evidence shows that the use of posterior approach in OA patients is associated with lower mortality and better functional outcome while the use of lateral approach in FNF patients gives lower dislocation rate. We recommend therefore the use of posterior approach in OA patients and lateral approach in FNF patients.

Dual mobility cups for preventing early hip arthroplasty dislocation in patients at risk: experience in a county hospital.

Dislocation remains a major concern after hip arthroplasty. We asked whether dual mobility cups (DMC) would improve early hip stability in patients with high risk of dislocation. We followed 34 patients (21 females, 13 males) treated between 2009 and 2012 with cemented DMC for hip revisions caused recurrent hip prosthetic dislocation or as a primary procedure in patients with high risk of instability. Functional outcome and quality of life were evaluated using Harris Hip Score and EQ-5D respectively. We found that the cemented DMC gave stability in 94%. Seven patients (20%) were re-operated due to infection. One patient sustained a periprosthetic fracture. At follow-up (6 to 36 months, mean 18), the mean Harris hip score was 67 (standard deviation: 14) and mean EQ-5D was 0.76 (standard deviation: 0.12). We concluded that treating patients with high risk of dislocation with DMC can give good stability. However, complications such as postoperative infection can be frequent and should be managed carefully.