Aims. Second-generation metal-on-metal (MoM) articulations in total hip arthroplasty (THA) were introduced in order to reduce wear-related complications. The current study reports on the serum cobalt levels and the clinical outcome at a minimum of 20 years following THA with a MoM (Metasul) or a ceramic-on-polyethylene (CoP) bearing. Methods. The present study provides an update of a previously published prospective randomized controlled study, evaluating the serum cobalt levels of a consecutive cohort of 100 patients following THA with a MoM or a CoP articulation. A total of 31 patients were available for clinical and radiological follow-up examination. After exclusion of 11 patients because of other cobalt-containing implants, 20 patients (MoM (n = 11); CoP (n = 9)) with a mean age of 69 years (42 to 97) were analyzed. Serum cobalt levels were compared to serum cobalt levels five years out of surgery. Results. The median cobalt concentration in the MoM group was 1.04 μg/l (interquartile range (IQR) 0.64 to 1.70) at a mean of 21 years (20 to 24) postoperatively and these values were similar (p = 0.799) to cobalt levels at five years. In the CoP control group, the median cobalt levels were below the detection limit (< 0.3 μg/l; median 0.15 μg/l, IQR 0.15 to 0.75) at 20 years. The mean Harris Hip Score was 91.4 points (61 to 100) in the MoM group and 92.8 points (63 to 100) in the CoP group. Conclusion. This study represents the longest follow-up series evaluating the serum cobalt levels after 28 mm head MoM bearing THA and shows that serum cobalt concentrations remain at low levels at a mean of 21 years (20 to 24) after implantation. Cite this article:Bone Joint Res. 2020;9(3):145–150

Objectives

Intra-articular injections of local anaesthetics (LA), glucocorticoids (GC), or hyaluronic acid (HA) are used to treat osteoarthritis (OA). Contrast agents (CA) are needed to prove successful intra-articular injection or aspiration, or to visualize articular structures dynamically during fluoroscopy. Tranexamic acid (TA) is used to control haemostasis and prevent excessive intra-articular bleeding. Despite their common usage, little is known about the cytotoxicity of common drugs injected into joints. Thus, the aim of our study was to investigate the effects of LA, GC, HA, CA, and TA on the viability of primary human chondrocytes and tenocytes in vitro.

Objectives. Taper junctions between modular hip arthroplasty femoral heads and stems fail by wear or corrosion which can be caused by relative motion at their interface. Increasing the assembly force can reduce relative motion and corrosion but may also damage surrounding tissues. The purpose of this study was to determine the effects of increasing the impaction energy and the stiffness of the impactor tool on the stability of the taper junction and on the forces transmitted through the patient’s surrounding tissues. Methods. A commercially available impaction tool was modified to assemble components in the laboratory using impactor tips with varying stiffness at different applied energy levels. Springs were mounted below the modular components to represent the patient. The pull-off force of the head from the stem was measured to assess stability, and the displacement of the springs was measured to assess the force transmitted to the patient’s tissues. Results. The pull-off force of the head increased as the stiffness of the impactor tip increased but without increasing the force transmitted through the springs (patient). Increasing the impaction energy increased the pull-off force but also increased the force transmitted through the springs. Conclusions. To limit wear and corrosion, manufacturers should maximize the stiffness of the impactor tool but without damaging the surface of the head. This strategy will maximize the stability of the head on the stem for a given applied energy, without influencing the force transmitted through the patient’s tissues. Current impactor designs already appear to approach this limit. Increasing the applied energy (which is dependent on the mass of the hammer and square of the contact speed) increases the stability of the modular connection but proportionally increases the force transmitted through the patient’s tissues, as well as to the surface of the head, and should be restricted to safe levels. Cite this article: A. Krull, M. M. Morlock, N. E. Bishop. Maximizing the fixation strength of modular components by impaction without tissue damage. Bone Joint Res 2018;7:196–204. DOI: 10.1302/2046-3758.72.BJR-2017-0078.R2

Objectives. All-suture anchors are increasingly used in rotator cuff repair procedures. Potential benefits include decreased bone damage. However, there is limited published evidence for the relative strength of fixation for all-suture anchors compared with traditional anchors. Materials and Methods. A total of four commercially available all-suture anchors, the ‘Y-Knot’ (ConMed), Q-FIX (Smith & Nephew), ICONIX (Stryker) and JuggerKnot (Zimmer Biomet) and a traditional anchor control TWINFIX Ultra PK Suture Anchor (Smith & Nephew) were tested in cadaveric human humeral head rotator cuff repair models (n = 24). This construct underwent cyclic loading applied by a mechanical testing rig (Zwick/Roell). Ultimate load to failure, gap formation at 50, 100, 150 and 200 cycles, and failure mechanism were recorded. Significance was set at p < 0.05. Results. Overall, mean maximum tensile strength values were significantly higher for the traditional anchor (181.0 N, standard error (. se). 17.6) compared with the all-suture anchors (mean 133.1 N . se. 16.7) (p = 0.04). The JuggerKnot anchor had greatest displacement at 50, 100 and 150 cycles, and at failure, reaching statistical significance over the control at 100 and 150 cycles (22.6 mm . se. 2.5 versus 12.5 mm . se. 0.3; and 29.6 mm . se. 4.8 versus 17.0 mm . se. 0.7). Every all-suture anchor tested showed substantial (> 5 mm) displacement between 50 and 100 cycles (6.2 to 14.3). All-suture anchors predominantly failed due to anchor pull-out (95% versus 25% of traditional anchors), whereas a higher proportion of traditional anchors failed secondary to suture breakage. Conclusion. We demonstrate decreased failure load, increased total displacement, and variable failure mechanisms in all-suture anchors, compared with traditional anchors designed for rotator cuff repair. These findings will aid the surgeon’s choice of implant, in the context of the clinical scenario. Cite this article: N. S. Nagra, N. Zargar, R. D. J. Smith, A. J. Carr. Mechanical properties of all-suture anchors for rotator cuff repair. Bone Joint Res 2017;6:82–89. DOI: 10.1302/2046-3758.62.BJR-2016-0225.R1

Objectives

Osteophytes are products of active endochondral and intramembranous ossification, and therefore could theoretically provide significant efficacy as bone grafts. In this study, we compared the bone mineralisation effectiveness of osteophytes and cancellous bone, including their effects on secretion of growth factors and anabolic effects on osteoblasts.

Objectives. Mechanical wear and corrosion at the head-stem junction of total hip arthroplasties (THAs) (trunnionosis) have been implicated in their early revision, most commonly in metal-on-metal (MOM) hips. We can isolate the role of the head-stem junction as the predominant source of metal release by investigating non-MOM hips; this can help to identify clinically significant volumes of material loss and corrosion from these surfaces. Methods. In this study we examined a series of 94 retrieved metal-on-polyethylene (MOP) hips for evidence of corrosion and material loss at the taper junction using a well published visual grading method and an established roundness-measuring machine protocol. Hips were retrieved from 74 male and 20 female patients with a median age of 57 years (30 to 76) and a median time to revision of 215 months (2 to 324). The reasons for revision were loosening of both the acetabular component and the stem (n = 29), loosening of the acetabular component (n = 58) and infection (n = 7). No adverse tissue reactions were reported by the revision surgeons. Results. Evidence of corrosion was observed in 55% of hips. The median Goldberg taper corrosion score was 2 (1 to 4) and the annual rate of material loss at the taper was 0.084 mm. 3. /year (0 to 0.239). The median trunnion corrosion score was 1 (1 to 3). Conclusions. We have reported a level of trunnionosis for MOP hips with large-diameter heads that were revised for reasons other than trunnionosis, and therefore may be clinically insignificant. Cite this article: H. S. Hothi, D. Kendoff, C. Lausmann, J. Henckel, T. Gehrke, J. Skinner, A. Hart. Clinically insignificant trunnionosis in large-diameter metal-on-polyethylene total hip arthroplasty. Bone Joint Res 2017;6:52–56. DOI: 10.1302/2046-3758.61.BJR-2016-0150.R2

Objectives

Rotator cuff tears are among the most frequent upper extremity injuries. Current treatment strategies do not address the poor quality of the muscle and tendon following chronic rotator cuff tears. Hypoxia-inducible factor-1 alpha (HIF-1α) is a transcription factor that activates many genes that are important in skeletal muscle regeneration. HIF-1α is inhibited under normal physiological conditions by the HIF prolyl 4-hydroxylases (PHDs). In this study, we used a pharmacological PHD inhibitor, GSK1120360A, to enhance the activity of HIF-1α following the repair of a chronic cuff tear, and measured muscle fibre contractility, fibrosis, gene expression, and enthesis mechanics.

Objectives

We sought to determine if a durable bilayer implant composed of trabecular metal with autologous periosteum on top would be suitable to reconstitute large osteochondral defects. This design would allow for secure implant fixation, subsequent integration and remodeling.

Objectives

Third-body wear is believed to be one trigger for adverse results with metal-on-metal (MOM) bearings. Impingement and subluxation may release metal particles from MOM replacements. We therefore challenged MOM bearings with relevant debris types of cobalt–chrome alloy (CoCr), titanium alloy (Ti6Al4V) and polymethylmethacrylate bone cement (PMMA).

Reported rates of dislocation in hip hemiarthroplasty (HA) for the treatment of intra-capsular fractures of the hip, range between 1% and 10%. HA is frequently performed through a direct lateral surgical approach. The aim of this study is to determine the contribution of the anterior capsule to the stability of a cemented HA through a direct lateral approach.

A total of five whole-body cadavers were thawed at room temperature, providing ten hip joints for investigation. A Thompson HA was cemented in place via a direct lateral approach. The cadavers were then positioned supine, both knee joints were disarticulated and a digital torque wrench was attached to the femur using a circular frame with three half pins. The wrench applied an external rotation force with the hip in extension to allow the hip to dislocate anteriorly. Each hip was dislocated twice; once with a capsular repair and once without repairing the capsule. Stratified sampling ensured the order in which this was performed was alternated for the paired hips on each cadaver.

Comparing peak torque force in hips with the capsule repaired and peak torque force in hips without repair of the capsule, revealed a significant difference between the ‘capsule repaired’ (mean 22.96 Nm, standard deviation (sd) 4.61) and the ‘capsule not repaired’ group (mean 5.6 Nm, sd 2.81) (p < 0.001). Capsular repair may help reduce the risk of hip dislocation following HA.

Cite this article: Bone Joint J 2015;97-B:141–4.

Objectives

An experimental piglet model induces avascular necrosis (AVN) and deformation of the femoral head but its secondary effects on the developing acetabulum have not been studied. The aim of this study was to assess the development of secondary acetabular deformation following femoral head ischemia.