Aims

We present a case series of ten metal-on-polyethylene total hip arthroplasties (MoP THAs) with delayed dislocation associated with unrecognised adverse local tissue reaction due to corrosion at the trunnion and pseudotumour formation.

Tapered fluted titanium stems are increasingly used for femoral revision arthroplasty. They are available in modular and non-modular forms. Modularity has advantages when the bone loss is severe, the proximal femur is mis shapen or the surgeon is unfamiliar with the implant, but it introduces the risk of fracture of the stem at the junction between it and the proximal body segment. For that reason, and while awaiting intermediate-term results of more recently introduced designs of this junction, non-modularity has attracted attention, at least for straightforward revision cases.

We review the risks and causes of fracture of tapered titanium modular revision stems and present an argument in favour of the more selective use of modular designs.

Cite this article: Bone Joint J 2016;98-B(1 Suppl A):50–3.

Adverse reaction to wear and corrosion debris is a cause for concern in total hip arthroplasty (THA). Modular junctions are a potential source of such wear products and are associated with secondary pseudotumour formation.

We present a consecutive series of 17 patients treated at our unit for this complication following metal-on-highly cross-linked polyethylene (MoP) THA. We emphasise the risk of misdiagnosis as infection, and present the aggregate laboratory results and pathological findings in this series.

The clinical presentation was pain, swelling or instability. Solid, cystic and mixed soft-tissue lesions were noted on imaging and confirmed intra-operatively. Corrosion at the head–neck junction was noted in all cases. No bacteria were isolated on multiple pre- and intra-operative samples yet the mean erythrocyte sedimentation rate was 49 (9 to 100) and C-reactive protein 32 (0.6 to 106) and stromal polymorphonuclear cell counts were noted in nine cases.

Adverse soft–tissue reactions can occur in MoP THA owing to corrosion products released from the head–neck junction. The diagnosis should be carefully considered when investigating pain after THA. This may avoid the misdiagnosis of periprosthetic infection with an unidentified organism and mitigate the unnecessary management of these cases with complete single- or two-stage exchange.

Cite this article: Bone Joint J 2015;97-B:1024–1030.

Non-modular tapered fluted, titanium stems are available for use in femoral revision. The combination of taper and flutes on the stem provides axial and rotational stability, respectively. The material and surface properties of the stem promotes bone on-growth. If the surgeon is confident and reasonably experienced in the surgical use of this sort of design and the case is relatively straightforward, a non-modular design is effective. It also potentially reduces implant inventory, and circumvents the potential problems of taper junction corrosion and fatigue fracture. There are reports of excellent survival, good clinical and functional results and evidence of subsequent increase in proximal bone stock.

Cite this article: Bone Joint J 2014;96-B(11 Suppl A):56–9.

Tapered, fluted, modular, titanium stems are increasingly popular in the operative management of Vancouver B2 and selected B3 peri-prosthetic femoral fractures. We have reviewed the results at our institution looking at stem survival and clinical outcomes and compared this with reported outcomes in the literature. Stem survival at a mean of 54 months was 96% in our series and 97% for combined published cases. Review of radiology showed maintenance or improvement of bone stock in 89% of cases with high rates of femoral union. Favourable clinical outcome scores have reported by several authors. No difference in survival or clinical scores was observed between B2 and B3 fractures. Tapered stems are a useful option in revision for femoral fracture across the spectrum of femoral bone deficiency.

Cite this article: Bone Joint J 2013;95-B, Supple A:17–20.

Tapered, fluted, modular, titanium stems have a long history in Europe and are increasing in popularity in North America. We have reviewed the results at our institution looking at stem survival and clinical outcomes. Radiological outcomes and quality of life assessments have been performed and compared to cylindrical non-modular cobalt chromium stems. Survival at five years was 94%. This fell to 85% at ten years due to stem breakage with older designs. Review of radiology showed maintenance or improvement of bone stock in 87% of cases. Outcome scores were superior in tapered stems despite worse pre-operative femoral deficiency. Tapered stems have proved to be a useful alternative in revision total hip arthroplasty across the spectrum of femoral bone deficiency.

Antibiotic impregnated articulating spacers are used in two-stage revision total knee arthroplasty to deliver local antibiotic therapy while preserving function. We have observed infection control in greater than 95% of cases with functional outcomes approaching those seen in revision for aseptic loosening. Higher failure has been observed with methicillin resistant organisms.

Purpose

Dislocation after revision total hip is a common complication. The purpose of this study was to assess whether a large femoral head (36/40mm) would result in a decreased dislocation rate compared to a standard head (32mm).

Purpose

There is a postulated association between increased serum metal ions and pseudotumour formation in patients with metal-on-metal hip replacements. The primary aim of this study was to assess the prevalence of pseudotumour in 31 asymptomatic patients with a large femoral head (LFH) metal-on-metal hip implant. This was compared to the prevalence of pseudotumour in 20 matched asymptomatic patients with a hip resurfacing (HRA) and 24 matched asymptomatic patients with a standard metal-on-polyethylene (MOP) total hip. A secondary objective was to assess possible correlation between increased serum metal ions and pseudotumour formation

Purpose

Measurements of patellar kinematics are essential to investigate the link between anterior knee pain following knee arthroplasty and patellar maltracking. A major challenge in studying the patellofemoral (PF) joint postoperatively is that the patellar component is only partially visible in the sagittal and close-to-sagittal radiographs. The narrow angular distance between these radiographs makes the application of conventional bi-planar fluoroscopy impossible. In this study a methodology has been introduced and validated for accurate estimation of the 3D kinematics of the PF joint post-arthroplasty using a novel multi-planar fluoroscopy approach.

Purpose

The outcome following isolated liner exchange for revision knee arthroplasty, while an attractive option for its simplicity, has a mixed outcome reported in the literature. We report our experience in patients who had a minimum of two years follow-up.

Purpose

The purpose of this study was to compare and evaluate the cost-effectiveness of the MIS Anterolateral Approach to that of the MIS Posterolateral and MIS Direct Lateral Approach.

Purpose: The purpose of this study was to evaluate the clinical effectiveness and outcomes of the ‘abductor sparing’ MIS Anterolateral approach (MIS Watson Jones/G3) in comparison to the MIS Direct Lateral and MIS Posterolateral approaches in primary total hip arthroplasty.

Method: A multicentre, prospective, randomized controlled trial was designed to evaluate for the superiority of the new MIS Anterolateral approach (MIS Watson Jones/ G3). The sample size calculation was performed for alpha .05, power .90, to evaluate for effect size 0.5 in WOMAC using repeated measures analyses with baseline WOMAC as covariate. A total of 156 patients consented to participate in the trial and patients were assigned to MIS Antero-lateral approach or alternate MIS approach (MIS Direct Lateral or MIS Posterolateral). Patients were subjected to standardized anaesthetic and perioperative management protocols and were evaluated at standardized intervals to evaluate endpoints of early recovery (3 months) as well as endpoints of 12 and 24 months respectively. The primary outcome of interest was WOMAC, however secondary outcomes included SF-36, as well as parameters of health resource utilization and complications. Univariate and multivariate analyses were perfomed.

Results: Patient groups were found to be similar at baseline with regards to demographics and baseline quality of life outcomes (p> .05). Multivariate and repeated measures analyses demonstrated no superiority of the MIS Anterolateral approach on outcomes of WOMAC and other quality of life measures in comparison to MIS Direct Lateral and MIS Posterolateral approaches (p> .05). Health care resource utlization was also similar with length of stay, blood transfusion requirements and complications (p> .05).

Conclusion: Our multicentre, prospective, randomized clinical trial demonstrates that the MIS Anterolateral approach is not superior to alternate MIS surgical approaches when evaluating outcomes of quality of life, complications, and health resource utilization. Surgeons should consider these outcomes, complications, and other relevant advantages and disadvantages of select surgical approaches when deciding on a technique for use in their orthopaedic practice.

Purpose: Between 1 and 2% of knee arthroplasties are complicated by infection with its associated patient morbidity. Two stage revision remains the gold standard with the minimum interval considered acceptable between the two stages as 6 weeks, but in some cases can be considerably longer depending on the patients’ clinical response to the first stage and intravenous antibiotics. The interval between the 2 stages is to allow eradication of the causative organism, however, this can result in considerable morbidity for the patient. Patients often have a poor range of movement, instability and considerable discomfort during this time and as a result have poor mobility. Further complications can be encountered at the time of the 2nd stage with considerable scarring of the soft tissues, in part secondary to the lack of mobilisation. Traditionally, spacers which are non-articulating have been used, however, problems of instability, scarring and bone erosion have been reported in the literature. The Prostalac knee spacer constitutes an antibiotic loaded acrylic cement body with a metal on polyethylene surface and enables the patient to undergo rehabilitation in the interval between the 2 stages and may also help maintain soft tissue planes as a result. Previous published results with a mean follow up of 48 months suggest the spacer is just as successful at eradicating infection (91%) as other techniques. The aim of this study is to review 119 patients with a minimum follow up of 5 years.

Method: The Prostalac Knee spacer has 2 components, a femoral and a tibial. Each are made of antibiotic-loaded acrylic cement with a small articulation of metal on polyethylene. The spacers are made from moulds so that a component of a suitable size and thickness could be made. This was a retrospective review of 119 consecutive patients. The inclusion criteria included all patients who had undergone a 2 stage revision with the Prostalac Knee spacer who had more than 5 years of follow up. Patients were assessed using the WOMAC, SF-12, Oxford Knee Score and the Knee Society Score.

Results: Thirteen patients (10.9%) out of a total of 119 had recurrence of infection. This gives an overall rate of control of infection of 89%. Of the 46 patients who completed the outcome score questionnaires with more than 5 years follow up, the mean WOMAC score was 65.9, Oxford Knee score was 61, SF-12 (physical component) was 35.7, SF-12 (mental component) was 54.8.

Conclusion: Although the Prostalac components include polyethylene and metal, they do not seem to have a detrimental impact on the rate of control of infection since our results were similar to those previously reported with other best practice techniques. It is our impression that the Prostalac functional spacer allows earlier pain free mobilisation, allowing the potential for earlier hospital discharge. The savings obtained from earlier hospital discharge greatly outweighing the increased cost of the Prostalac functional spacer system.

Purpose: Subchondral cortical and trabecular bone mineral density (BMD) may increase and/or decrease during different stages of osteoarthritis (OA) disease progression. 2D in-vivo imaging studies examining direct associations between increased proximal tibial BMD and knee OA offer conflicting results, which may be due to the inherent limitations of 2D BMD imaging tools. Our objective was to compare existing and novel 3D imaging techniques for distinguishing subchondral bone properties in OA and normal cadaveric tibiae.

Method: Eight intact cadaver knees from five donors (4M:1F; age: 77+/−10) were repositioned and scanned three times using QCT (0.5mm isotropic resolution, 0.15mSv dosage). BMD was assessed using

computed tomography absorptiometry (CT-OAM) which uses maximum intensity projections to assesses peak density values within subchondral bone, and

Average BMD at normalized depths of 0–2.5mm, 2.5–5.0mm, and 5.0–10mm from the surface were assessed using CT-TomasD. Regional analyses were performed consisting of:

medial/lateral (M/L) BMD ratio, and

Each bone was assessed for OA using a modified-KL scoring system: Normal (mKL=0); Early-OA (1–2); and Late-OA (3–4).

Results: OA was identified in four compartments of three tibiae (1 late OA+valgus, 1 late OA+varus, 1 early OA+neutral). Larger density differences between OA and normal knees were noted using CT-TOMASD compared with CT-OAM. CT-TomasD demonstrated that the two knees with late OA demonstrated M/L BMD ratios differing by more than 3.4 SD compared with normals, with peak cores higher than normals across all depths. The knee with early OA and neutral alignment demonstrated M/L ratios less than normals while core differences were highest proximally, with density becoming lower than normals with increasing depth.

Conclusion: CT-TomasD demonstrated larger differences between OA and normal subjects when compared with CT-OAM differences. This may be due to CT-OAM primarily assessing peak density within the thin subchondral cortical endplate; a region demonstrating fairly uniform peak densities within a limited range.

Purpose: Giant cell tumour (GCT) of the distal radius is associated with high local recurrence rates unless the tumour is aggressively resected, which often leaves a significant skeletal defect. The purpose of this study is to compare the functional outcomes of two commonly used reconstructive techniques, vascularised free fibular transfer (VFF) and non-vascularised structural iliac crest transfer (NIC).

Method: Patients treated for giant cell tumour of the distal radius in either Vancouver or at Mount Sinai Hospital, Toronto were identified in the prospectively collected databases maintained in each centre. Twenty-seven patients were identified, 14 of whom underwent VFF transfer as their primary procedure. The two groups were comparable for age, sex and tumour grade. Functional outcomes were assessed with TESS, MSTS, DASH and the Ankle Osteoarthritis Scale.

Results: Fourteen patients were included in the VFF group, 13 of which were performed as the primary index procedure, one followed prior cementation. Thirteen patients underwent NIC, one followed prior cementation. Two local recurrences occurred in the VFF group and one in NIC group, all treated with local excision. In the VFF group three patients underwent further surgery for cosmesis, hardware removal and tendon release respectively. One is scheduled for future surgery for tendon release. In the NIC group two patients suffered infections requiring debridement, one of which ultimately went on to require free fibular transfer. This patient’s results were included in the NIC group as this was the index procedure. Functional scores showed no differences between the two groups on any of the parameters studied for the upper limb (Mann-Whitney test). The Ankle osteoarthritis scale had a median score of 9% for the six patients on which it was available.

Conclusion: Both VFF and NIC are effective surgical techniques that result in a well-functioning wrist arthrodesis. VFF may be more useful where there is a significant skin defect from previous interventions. We were unable to demonstrate any difference in functional scores between VFF and NIC.

Purpose: Chondral injuries of the knee are commonly seen at arthroscopy, yet there is no consensus on the most appropriate treatment method. However, untreated cartilage injury predisposes to osteoarthritis contributing to pain and disability. For cell-based cartilage repair strategies, an ex-vivo expansion phase is required to obtain sufficient numbers of cells needed for therapy. Although recent reports demonstrated the central role of oxygen for the function and differentiation of chondrocytes, little is known of the effect of physiological low oxygen concentrations during the expansion of the cells and whether this alters their chondrogenic capacity.

Method: Initial studies of chondrocyte expansion were performed in mature mice, with cells expanded at either atmospheric oxygen tension (21%) or 5% 02 in monolayer cultures. Chondrogenic differentiation was subsequently assessed via micromass culture. Having determined that oxygen tension influences murine chondrocyte expansion and differentiation, similar studies were conducted using adult human chondrocytes taken from knee arthroplasty off-cuts, with mRNA expression of select genes involved in the chondrogenic program analyzed by q-PCR.

Results: Cellular morphology was improved in hypoxic culture, with a markedly more fibroblastic appearance seen after greater than 2 passages in 21% O2. Micromass cultures maintained in hypoxic conditions demonstrated stronger staining with Alcian blue, indicating stronger expression of cartilaginous glycosaminoglycans. Collagen type II mRNA expression was two-fold higher in cells expanded at 5% as compared to expansion at 21% O2. Micromass cultures grown at 21% O2 showed up to a twofold increase in the tissue content of glycosaminoglycans when formed with cells expanded at 5% instead of 21% O2. However, no differences in the mRNA expression or staining for collagen type II protein were observed in these micromass cultures. Hypoxia (5% O2) applied during micromass cultures gave rise to tissues with low contents of glycosaminoglycans.

Conclusion: In-vivo, chondrocytes are adapted to a hypoxic environment. Taking this into account, applying 5% O2 in the expansion phase in the course of cell-based cartilage repair strategies, may result in a repair tissue with higher quality by increasing the content of glycosaminoglycans.

Purpose: Core needle biopsy is increasingly accepted for the diagnosis of bone and soft-tissue tumours. Advantages over open biopsy include reduced morbidity, time and cost; however diagnostic accuracy remains a concern. Our objective was to assess and compare the diagnostic accuracy of core needle, open, and fine needle biopsies.

Method: We reviewed 286 cases collected in a prospective database between 2004 and 2007. Of these, 229 had core needle, 32 open, and 25 fine needle biopsies. 230 had soft-tissue lesions, 56 had bone lesions. The results of these biopsies were compared to the final resection diagnosis for accuracy and, where inaccurate, any effects on management.

Results: Ninety-two percent of the core needle, 100% of the open and 72% of the fine needle biopsies had adequate tissue to make a diagnosis. Of the adequate specimens, the accuracy of core/open/fine needle biopsy was 96%, 97% and 94% for determining malignant versus benign; of the correctly identified malignant lesions 97%, 100% and 80% were accurate for histological grade; and 79%, 84%, 59% for histological subtype.

Conclusion: Core needle biopsy yields diagnostic results comparable to open biopsy for determining malignancy and grade in bone and soft-tissue tumours. Fine needle biopsy has a high inadequate sampling rate and should not be used for diagnosing bone and soft-tissue tumours. Given the reduced cost and morbidity associated with core needle biopsies we believe they should be used routinely for diagnosis where possible, and open biopsy reserved for situations where an inadequate specimen is obtained or core biopsy is not feasible.

Purpose: Resection of pelvic sarcoma with limb preservation (internal hemipelvectomy) is a major undertaking. Resection requires large areas of soft-tissue to be removed. Because of wound complications, we manage these defects with immediate tissue transfer (ITT) at the time of resection when a large defect is anticipated. This study compares the outcomes of ITT with primary wound closure (PWC).

Method: Twenty patients undergoing 22 separate procedures (1995–2007) were identified in our prospectively maintained database. Demographics, tumour type, operative data and complications, and functional scores (MSTS-1993, TESS) were collected.

Results: Twelve defects were managed with ITT, nine with pedicled myocutaneous vertical rectus abdominis (VRAM) flaps (one received double VRAM flaps due to the large defect), two with tensor fascia lata (TFL) rotation flaps (one augmented by local V-Y advancement, the other with gluteus maximus rotation flap) and one received latissimus dorsi free tissue transfer. Four wound complications necessitated operative intervention in this group: two debrided VRAM flaps went on to heal and the two TFL flaps required revision: one to VRAM flap and the other to a latissimus dorsi free flap which ultimately suffered chronic infection and hindquarter amputation was performed. Ten defects were managed with PWC, and 5 wound complications occurred, all five suffered infection, one developed hematoma and one dehisced. One wound resolved with debridement, two healed after revision to pedicled gracilis and gluteus maximus myocutaneous flaps. Two patients were converted to hindquarter amputation due to chronic infection. Functional scores were collected on 8 of 12 living patients, at time of writing. The mean TESS scores were 83 and 73 in the ITT and PWC groups. Five patients in the ITT and 3 in the PWC group were deceased.

Conclusion: Soft-tissue closure following pelvic sarcoma resection remains a difficult challenge, and our experience reflects that. There were fewer wound complications (33% v 50%) and slightly better function with ITT than PWC, but this was not statistically significant due to the small size of our study. Although small, this study suggests ITT should be considered whenever a large soft tissue defect is anticipated.

Purpose: The purpose of this study was to prospectively evaluate a consecutive series of patients receiving metal on metal hip resurfacing arthroplasty with regards to outcomes and complications at minimum of 2 years follow-up.

Method: A prospective evaluation of all patients receiving hip resurfacing was performed including baseline evaluation (demographics, WOMAC, SF12, Oxford Hip Score) and minimum 2 year follow-up assessment (WOMAC, SF12, Oxford Hip Score, UCLA activity score, Patient Satisfaction, Complications). No patients were lost to follow-up.

Results: 143 hips in 127 patients received metal-on-metal hip resurfacing arthroplasty. The mean age was 52 years and the primary diagnosis was osteoarthritis or avascular necrosis, Significant improvements were noticed across all baseline quality of life instruments (p< .05) with final mean WOMAC and Oxford Scores 95 (normalized 0–100). Final post-op satisfaction was mean 95 out of 100. Two patient sustained post-operative femoral neck fractures and required revision. An additional two patients required revision for ongoing hip pain. One patient sustained a sciatic nerve palsty and one additional patient required acetabular component repositioning on the same day as the index procedure. Revision procedures involved conversion of resurfacing femoral component to cementless total hip stem with large diameter metal head and preservation of acetabular component. Acetabular component survivorship is 99% and femoral component survivorship is 97% at 2 year follow-up.

Conclusion: Our short to midterm data, from an independant center, suggests excellent improvement in quality of life with high levels of patient satisfaction and postop acitivity level. Our comprehensive post-operative quality of life assessment demonstrates restoration of the hip to rival that of the normal non-arthritic hip joint. Complications unique to resurfacing arthroplasty occur and were not predictable based on pre-operative or intra-operative patient-specific features.