Introduction

Bone and joint infection (BJI) is often characterized by severe inflammation and progressive bone destruction. Osteocytes are the most numerous and long-lived bone cell type, and therefore represent a potentially important long-term reservoir of bacterial infection. Staphylococcus aureus is known to establish stable intracellular osteocytic infections, however, little is known about the less virulent yet second most prevalent BJI pathogen, S. epidermidis, associated with late-diagnosed, chronic BJI. Thus, this study sought to establish an in vitro model to study the infection characteristics of S. epidermidis in human osteocyte-like cells.

This study aimed to quantify self-reported outcomes and walking gait biomechanics in patients following primary and revision THA. The specific goals of this study were to investigate: (i) if primary and revision THA patients have comparable preoperative outcomes; and (2) if revision THA patients have worse postoperative outcomes than primary THA patients.

Forty-three patients undergoing primary THA for osteoarthritis and 23 patients undergoing revision THA were recruited and followed longitudinally for their first 12 postoperative months. Reasons for revision were loosening (73%), dislocation (9%), and infection (18%). Patients completed the Hip dysfunction and Osteoarthritis Outcome Score (HOOS), and underwent gait analysis preoperatively, and at 3 and 12 months postoperatively. A 10 camera motion analysis system (V5 Vantage, Vicon, UK) recorded marker trajectories (100 Hz) during walking at self- selected speeds. A generic lower-body musculoskeletal model (Gait2392) was scaled using principal component analysis [1] and the inverse kinematics tool in Opensim 3.3 was used to compute joint angles for the lower limbs in the sagittal plane. Independent samples t-test were used to compare patient reported outcomes between the primary and revision groups at each timepoint. Statistical parametric mapping was used to compare gait patterns between the two groups at each timepoint.

Preoperatively, patients undergoing primary THA reported significantly worse pain (p<0.001), symptoms (p<0.001), function (p<0.001), and quality of life (p=0.004). No differences were observed at 3 and 12 months postoperatively between patients who had received a primary or revision THA. The only observed difference in gait pattern was that patients with a revision THA had reduced hip extension at 3 months, but no differences were observed preoperatively and 12 months.

Despite the suggestions in the literature that revision THA is bound to have worse outcomes compared to primary THA, we found no differences in in patient-reported outcomes and gait patterns at 12 months postoperatively. This suggests that it may be possible, in some circumstances, for patients following revision THA to achieve similar outcomes to their peers undergoing primary THA.

Introduction

Severely comminuted, displaced acetabular fractures with articular impaction in the elderly population present significant treatment challenges. To allow early post-operative rehabilitation and limit the sequelae of immobility, treatment with acute total hip replacement (THA) has been advocated in selected patients. Achieving primary stability of the acetabular cup without early migration is challenging and there is no current consensus on the optimum method of acetabular reconstruction. We present clinical results and radiostereometric analysis of trabecular metal (TM) cup cage construct reconstruction in immediate THA without acetabular fracture fixation.

Open reduction and internal fixation of tibial plateau fractures is traditionally performed through an anterior, anterolateral or an anteromedial approach and more recently a posteromedial approach. These approaches allow satisfactory access to the majority of fracture patterns with the exception of posterolateral tibial plateau fractures.

To improve access to posterolateral tibial plateau fractures, we developed a posterolateral transfibular neck approach that exposes the tibial plateau between the posterior margin of the iliotibial band and the PCL. The approach can be combined with a posteromedial and/or an anteromedial approach to the tibial plateau. Since April 2007, we have used this approach to treat nine posterolateral tibial plateau fractures. All cases were followed up prospectively. Fracture reduction was assessed on radiographs, CT scans and arthroscopicaly. Maintenance of fracture reduction was assessed with radiostereometric analysis. Clinical outcomes were measured using Lysholm and KOOS scores.

Anatomic or near anatomic reduction was achieved in all cases. All fractures healed uneventfully and no loss of osteotomy or tibial plateau fracture reduction was identified on postoperative plain X-rays. In the cases monitored with radiostereometric analysis, the fracture fragments displaced less than 2 mm during the course of healing. All osteotomies healed either at the same rate or quicker than the tibial plateau fractures. There were no signs and no symptoms of lateral or posterolateral instability of the knee during or after the healing of the osteotomy. There were no complications related to the surgical approach, including the fibular head osteotomy. All wounds healed uneventfully and there were no symptoms related to the CPN. The patient reported outcomes recorded for this group at six months, using the Lysholm score (mean 71, median 77, range 42–95), compared favourably to the entire cohort of 33 patients treated operatively at our institution for a tibial plateau fracture and followed up prospectively during the same time period (mean 64, median 74, range 20–100).

The posterolateral transfibular approach for lateral tibial plateau fractures is an approach that should be considered for a certain specific pattern of fractures of the lateral tibial plateau. Our preliminary results demonstrated no complications through the learning curve of the development of this technique.

Sensitive and accurate measures of osteolysis around TKR are needed to enhance clinical management and assist in planning revision surgery. Therefore, our aim was to examine, in a cadaver model of osteolysis around TKR, the sensitivity of detection and the accuracy of measuring osteolysis using Xray, CT and MRI.

Fifty-four simulated osteolytic lesions were created around six cadaver knees implanted with either a cemented or cementless TKR. Twenty-four lesions were created in the femur and thirty in the tibia ranging in size from 0.7 cm3 to 14 cm3. Standard anteroposterior and lateral fluoroscopically guided radiographs, CT and MRI scans with metal reduction protocols were taken of the knees prior to the creation of lesions and at every stage as the lesion sizes were enlarged. The location, number and size of the lesions from images obtained by each method were recorded.

The sensitivity of osteolytic lesion detection was 44% for plain radiographs, 92% for CT and 94% for MRI. On plain radiographs, 54% of lesions in the femur and 37% of lesions in the tibia were detected. None of the six posterior lesions created in the tibia were detected on the AP radiographs; however, three of these six lesions were detected on the lateral radiographs. CT was able to detect lesions of all sizes, except for four lesions in the posterior tibia (mean volume of 1.2 cm3, range 1.06–1.47 cm3). Likewise, MRI was very sensitive in detecting lesions of all sizes, with the exception of three lesions, two of which were in the femur and one was in the medial condyle of the tibia (mean volume of 1.9 cm3, range 1.09–3.14 cm3). Notably, all six posterior tibial lesions, which could not be detected using AP radiographs, were detected by MRI.

This study demonstrates the high sensitivity of both CT and MRI (which uses no ionising radiation) to detect simulated knee osteolysis and can therefore be used to detect and monitor progression of osteolysis around TKR. The study also shows the limitations of plain radiographs to assess osteolysis.

Background: Good results have been reported for cemented femoral total hip arthroplasty in young patients from centres with expert surgeons but what is unknown are the results when surgeries are performed by a group of surgeons with varying experience in total hip replacement. The purpose of this study was to evaluate the outcome of primary total hip arthroplasty using a polished cemented polished collarless double tapered stem in young patients aged less than 55 years performed by a group of surgeons with varying experience in total hip replacement.

Methods: One hundred and ninety seven arthroplasties in 169 patients were performed between 1988 to 2005. The procedures were performed by surgeons with varying arthroplasty experience. Follow-up was 2 to 19 years (median 8 years). Clinical outcomes, radiographic evaluations and survivorship analyses were undertaken.

Results: Of the 197 femoral stems, eight were revised, but none for aseptic loosening. Four stems underwent cement within cement revision for recurrent dislocation, leg length discrepancy, infection and to assist cup revision. Two stems were revised for periprosthetic fractures. Two stems were revised for infection. No stems were classified as probably or possibly loose. Median stem within cement subsidence was 1.0mm. Two stems have more than 5mm vertical subsidence and in the absence of radiolucent lines or associated pain they were not considered loose. At long term follow-up the overall incidence of femoral osteolysis was 7% (n=13 hips). At latest patient follow-up the median Harris Hip and pain scores were respectively 81 (range 34 to 100) and 40 (range 10 to 44). Survivorship of the polished collarless double tapered stems at 13 years using the endpoint revision for aseptic loosening was 100% (worst case analysis 96.5%).

Conclusion: This study confirms that good results of cemented polished collarless double tapered stems in the younger patient can be achieved by a group of surgeons with varying experience in total hip replacement. The ability to perform a minor stem revision, cement within cement, for other reasons than aseptic loosening further strengthens the indications for these type of implants in young patients.

Differentially loaded radiostereometric analysis (DLRSA) uses RSA whilst simultaneously applying load to the bones under investigation. This technique allows measurement of interfragmentary translations and rotations under measured weight bearing and joint movement. We have recently introduced this technique to monitor tibial plateau fracture healing. This paper presents our preliminary results.

Twelve patients with a 41 B2, B3, C2, or C3 fracture were followed for a minimum of three months. RSA beads were inserted in the largest osteochondral fragment and the adjacent metaphysis. Knee flexion was restricted to 60° for 6 weeks. After partial weight bearing (20kg) between 2 and 6 weeks, patients progressed to full weight bearing. Follow up included clinical and radiological examinations and patient reported outcome scores (Lysholm, KOOS). DLRSA examinations included RSA radiographs in 60° flexion and under measured weight bearing. Significant interfragmentary displacement was defined as translations greater than 0.5mm and/or rotations greater than 1.5°.

There was no loss to follow-up. Longitudinal RSA follow-up: Follow-up RSA radiographs were compared to postoperative examinations. Osteochondral fragment depression was less than 0.5mm in seven patients and between 2 and 4mm in the remaining five patients. Significant interfragmentary displacement after three months was recorded in three patients. DLRSA flexion results: Under 60° of flexion, translations over 0.5mm were recorded in five patients (one postoperatively; one at 2 weeks; two at 6 weeks; and one postoperatively, at 2 weeks and at 3 months). Rotations over 1.5° were recorded in six patients (one postoperatively; two at 2 weeks; one at 6 weeks; one at 2 weeks, 3 months and 4.5 months; and one postoperatively, at 2 weeks, 3 months and 6 months). DLRSA weight bearing results: Under partial weight bearing at two weeks, two patients recorded significant translations, one involving a significant rotation. Under weight bearing as tolerated, three patients recorded significant translations (one at 6 weeks; and two at 18 weeks) and four patients recorded significant rotations (one at 6 weeks; one at 18 weeks; and two at 12 and 18 weeks). Patient Reported Outcomes: Both the Lysholm and KOOS scores improved between 6 weeks and 3 months. DLRSA provides new insight and perspective in tibial plateau fractures. Some fractures take more than three months to heal. Our current rehabilitation protocol was safe in most patients, however significant interfragmentary displacement was encountered in 17% at the 2 week followup, raising questions about the quality of the initial stability.