Introduction

Reverse hybrid total hip replacement (THR) offers significant theoretical benefits but is uncommonly used. Our primary objective was to evaluate implant survival with all cause revision and revision for aseptic loosening of either component as endpoints.

Introduction

A fractured hip is the commonest cause of injury related death in the UK. Prompt surgery has been found to improve pain scores and reduce the length of hospital stay, risk of decubitus ulcer formation and mortality rates. The hip fracture Best Practice Tariff (BPT) aims to improve these outcomes by financially compensating services, which deliver hip fracture surgery within 36 hours of admission. Ensuring that delays are reserved for patients with conditions which compromise survival, but are responsive to medical optimisation, would facilitate enhanced outcomes and help to achieve the 36-hour target.

We aimed to identify medical conditions associated with patients failing to achieve the 36-hour cut off, and evaluated whether these were justified by calculating their associated mortality risk.

Aim

To review the outcome of deep prosthetic infection in patients following hip hemiarthroplasty surgery.

Background: Chronic prosthetic joint infection is a cause of patient morbidity and can be challenging to treat. Surgeons performing revision arthroplasty of the hip and knee are confronted with a growing number of patients with extensive loss of bone stock. The use of a modular endoprosthesis is a possible method of treatment in such patients.

Aim: The purpose of this study was to assess the functional outcomes and the success of a single and two stage revision procedure in eradicating chronic prosthetic joint infection using a femoral endoprosthesis.

Methods: A prospective database was reviewed of 20 patients who underwent a proximal, total or distal femoral endoprosthetic replacement after chronic prosthetic infection. Radiographs performed at the time of latest follow up were evaluated for signs of loosening, osteomyelitis and implant failure. The functional status was assessed using the Short Form (SF)-36 health survey score, Toronto extremity salvage score (TESS) and the Enneking score.

Results: Thirteen patients underwent a single stage revision procedure and seven had been treated with a staged revision. At the latest follow up none of the 13 patients treated with a single stage procedure had evidence of ongoing infection. Of the seven patients who had a staged revision, 3 patients had evidence of ongoing infection. The mean pre operative Enneking score for the entire group was 17.1 points and this improved to 47.5 points post operatively (p< 0.0002). The mean pre operative TESS score for the entire group was 42% and this improved to 59% post operatively (p< 0.005). There was also a statistically significant improvement in all of the components of the SF-36 score.

Conclusion: We believe that the use of a modular endo-prosthesis in the treatment of chronic prosthetic joint infection is a successful and viable option in eradicating infection, preserving the limb and providing a good functional result.

Purpose: To determine the outcome following anterior tibial spine avulsion in skeletally mature patients.

Summary: The study group comprised 83 knees with anterior tibial spine avulsion. The mean age of patients at injury was 35. Twenty knees with displaced tibial spine fractures were treated with fixation of the tibial spine and 63 patients with undisplaced or minimally displaced fractures were treated non-operatively.

Twenty two percent of the non operatively managed knees developed symptomatic instability and 10% of knees treated with tibial spine fixation developed instability (p=0.22). Stiffness was more common in knees treated with tibial spine fixation than in knees managed nonoperatively (60% vs 19%, p < 0.0005). There was a tendency for increased stiffness in older patients treated with surgical fixation of the tibial spine.

Conclusion: Tibial spine fracture in skeletally mature patients is associated with significant risk of knee stiffness and instability.

Introduction: Human bone marrow stromal stem cells(BMSSC’s) have the ability to differentiate into a variety of mesenchymal cell types including osteoblasts, fibroblasts, adipiocytes and myocytes. These stromal cells are involved in the process of bone formation during the healing of fractures. Collagen lyophilisate is a sterile extract of bovine demineralised bone matrix. This material contains proteins removed from bone that may control the differentiation of osteoblasts from BMSSC’s. These proteins are localised within collagen type 1. The aim of this study was to determine the effects of collagen lyophilisate on the osteogenic differentiation of bone marrow stromal stem cells cultured in vitro.

Methods: Bone marrow was aspirated from the iliac crest of a human donor who was undergoing an unrelated elective orthopadic surgical procedure. Stromal stem cells were isolated from marrow, cultured and then characterised using immunofluorescent antibodies to Stro −1, a stromal stem cell marker. 3x10⁴ BMSSC’s were seeded into each of 3 culture wells and incubated with standard growth medium or standard medium with collagen lyophilisate diluted 1:50 or 1:100. Cells were cultured for a maximum duration of 30 days. At selected time intervals until day 30, osteogenic differentiation was assessed by determination of alkaline phosphatase, osteopontin, pro collagen carboxyterminal (type 1 collagen synthesis) and calcium in cultures using specific assays.

Results: Cells cultured in collagen lyophilisate displayed a polygonal morphology early in the culture period and later formed complex aggregates. Cells in control cultures maintained a fibroblstic morphology until confluence. On day 21 alkaline phosphatase activity was significantly higher in collagen lyophilisate containing cultures than control cultures. Osteopontin levels were not enhanced in the collagen lyophilisate containing cultures. Type 1 collagen synthesis was higher in the collagen lyophilisate 1:50 group than all other groups at day 14. No differences in type 1 collagen synthesis were detected between cultures at other time periods. Calcium was not detected in any of the control cultures for the duration of the culture period. In contrast, calcium was detected in collagen lyophilisate containing cultures on day 15.

Conclusion: Collagen lyophilisate resulted in changes in cellular morphology and arrangement. The ability of collagen lyophilisate to enhance alkaline phosphatase activity, increase collagen type 1 expression and stimulate the deposition of calcium in stromal stem cell cultures provides evidence that it has osteogenic properties.

Introduction: Bone marrow derived stromal stem cells (BMSSC’s) have the ability to differentiate into a variety of mesenchymal tissues including bone. The objective of this study was to evaluate the use a hydroxyapatite – BMSSC (HA-BMSSC) composite graft for posterior spinal fusion in a rabbit model.

Method: The HA- BMSSC composite graft was prepared by seeding rabbit marrow derived BMSSC’s onto 5 grams of HA granules which were cultured for a further 7 days prior to implantation. Bilateral posterior L4–L5 interlamina spinal fusion was performed using the HA- BMSSC composite graft (4 Rabbits), hydroxyapatite(HA) granules (6 rabbits) or autologous bone graft obtained from the iliac crest (6 rabbits). Rabbits were sacrificed at 5 weeks. Fusion was assessed by manual palpation. Quantitative histological analysis of cartilage, fibrous tissue and bone in the mid portion of the graft was performed using image analysis software.

Results: Three of four of the HA- BMSSC grafts fused successfully compared to 5 of 6 of the autologous bone grafts and 0 of 6 of the HA control grafts. The fusion rate was significantly higher in the iliac crest and HA- BMSSC groups than the HA control group (p< 0.05). In both the HA control and HA stem cell composite grafts there was ingrowth of new bone and encasement of HA granules by new trabecular bone at the graft – host interface. Within the mid region of the grafts there was bone formation in 2 of four fusion masses in the HA- BMSSC group comprising 26% and 45% of tissue in the area examined. In contrast bone formation was seen in the centre of only one of the six 6 HA fusion masses and amounted to only 2% of tissue. There was no significant difference in average percentage area of new bone, cartilage or fibrous tissue within the central region of the HA and HA-BMSSC grafts. There was a higher mean percentage area of new bone formation within the autologous bone graft (27%) than the HA control group (0.3%). p< 0.02.

Discussion: The BMSSC –HA composite was as effective as autologous graft and superior to HA in promoting fusion, but HA when used alone was ineffective. A positive finding to support the osteogenic potential of the stem cell loaded HA granules was the presence of moderate amounts of enchondral new bone isolated within the central regions of the graft away from the graft host interface in 2 of 4 fusion masses. In contrast the HA control grafts only supported significant amounts of bone formation in the periphery, adjacent to the host bed.

An analysis on prospective data collected on our hip database was carried out on all patients undergoing primary cemented unilateral total hip arthroplasty in the last 5 years comparing the short term outcomes between diabetics and non-diabetics. There were 1220 non-diabetics and 77 diabetics identified from the database with at least 3 years follow up. (average 3.6 years). We found no significant difference with respect to age, sex and diagnosis between the 2 groups. Diabetics did have a significantly higher BMI (30.2 versus 27.7, p< 0.001) and higher incidence of coronary artery disease (31% versus 15%, p< 0.001) We found no increase in the rate of deep periprosthetic infection, superficial wound complications, dislocation, blood loss and DVT between diabetics and non-diabetics even after adjusting for potential confounders of age, sex, diagnosis, BMI and the presence of coronary artery disease. The only factor that was found to be significantly different between the 2 groups was length of stay (10.73 versus 9.56 days, p< 0.05). Further analysis of the diabetic group only showed no difference with regard the same outcomes between insulin-dependent, diet-controlled and diet and oral hypoglycaemic-controlled patient subsets. From this study we conclude that at the time of taking informed consent from diabetic patients undergoing total hip arthroplasty the only potential difference from non-diabetics is that the length of stay may be longer.

The identification of preoperative risk factors for blood transfusion following total joint arthroplasty facilitates the selection of patients for blood-conservation strategies such as preoperative autologous blood donation. We reviewed prospective data on 1016 unilateral THRs to establish the preoperative risk factors associated with peri-operative blood transfusion.

On average, transfused patients were older, with lower preoperative haemoglobin, weight, height and body mass indices than patients who were not transfused. When the relationship between variables and transfusion was examined by multivariate analysis with multiple logistic regressions, only preoperative haemoglobin and weight were identified as significant independent factors increasing the risk of transfusion (p < 0.001). A threefold increase in transfusion risk was associated with haemoglobin below 12.

Patients of low weight or with haemoglobin below 12 should be considered for blood-conserving interventions.

Objective-Study Design: Recognizing the value of intraoperative SEP monitoring in scoliosis and other spinal surgery, we applied prospectively continuous SEP recording during reconstructive procedures in 82 patients who sustained 20 cervical, 8 thoracic, 6 thoraco-lumbar, and 48 lumbar vertebral fractures or fractures-dislocations to investigate its efficacy in spinal trauma.

Material: Seventy-one patients underwent single anterior or posterior operations, and 11 combined anterior-posterior procedures. Forty patients had incomplete injuries, and 42 had no preoperative neurological deficit. SEP trace amplitude at insertion of electrode was considered as the baseline value, and was compared to the lowest intraoperative signal amplitude and the amplitude at completion of operation.

Results: Fifty-nine patients had a depression in wave amplitude of more than 25% during surgery; in 25 patients the trace fell by more than 50%, and in 7 cases a more than 75% diminution was recorded. A loss of 50% in SEP signal amplitude showed 67% sensitivity, and 71% specificity in predicting neurologic outcome. Patients with a fall in SEP amplitude of more than 50% that did not recover at completion of the surgical procedure demonstrated an increased risk of neurological compromise (p< .01). Increasing trace deterioration threshold from 50 to 60% improved specificity to 81% without compromising sensitivity. There was also 100% correlation between the side of the amplitude drop and the side of neurological loss in the trunk or limb (p< .001). A total number of 22 patients had improved SEP recordings before skin closure; 19 of these patients demonstrated an improved neurologic function after the operative procedure. In these 19 patients a positive statistical association could be documented between the signal changes and the neurological outcome (p< .05). Nevertheless, 2 of the patients with up to 20% improvement in the trace amplitude compared to the original control measurement presented deterioration in their neurological picture in the postoperative period. In 17 patients the SEP waveform amplitude was unchanged at conclusion of the operation; in those cases the neurological functional level post-surgery was equally unaltered. No significant difference was obtained when comparing the systolic blood pressures or the core temperatures at skin closure between the different outcome groups (p> .05). A loss of more than 50% in SEP amplitude occurred with significantly increased incidence during the anterior compared to the posterior spinal procedures (p< .001). More than 20% recovery in signal amplitude at conclusion of the procedure in patients with incomplete injuries was correlated with favorable neurological function.

Conclusions: Persistent intraoperative decrement in SEP amplitude and poor restitution at completion of surgery increase the risk for postoperative neurologic compromise. In this series, continuous intraoperative SEP monitoring appeared to be adequately reproducible, sufficiently reliable, and therefore a practical tool in monitoring operative procedures for spinal trauma. Even though compared to deformity surgery the method is less sensitive and specific, it may help reduce the incidence of devastating neurologic injury during the operation on an already compromised neural cord, and can provide good prediction in terms of postoperative neurological outcome. Thus, it could be considered a useful surgical adjunct in the management of patients with spinal trauma.

Introduction: Somatosensory evoked potentials are monitored during the surgical treatment of spinal disorders to reduce the risk of cord injury. Whilst studies have examined its role in patients undergoing correction of idiopathic and neuromuscular scoliotic curves, its effectiveness in patients undergoing operative treatment for spinal injury is less certain.

Methods and Results: We reviewed the medical records of patients who underwent surgery for spinal trauma. between 1995 and 2000. There were 82 patients with adequate data for analysis who underwent 83 spinal reconstructive procedures. We recorded the age at injury, diagnosis, time of operation, levels instrumented, systolic and diastolic blood pressures and surgical approach. The intraoperative somatosensory evoked potential (SSEP) traces were examined. The SSEP at insertion of electrode was taken as the control level. The highest and lowest intraoperative somatosensory evoked potentials and SSEP at closure were noted and expressed as a percentage of the control value.

Forty patients (48%) had a pre-operative neurological deficit. Neurological deterioration occurred postoperatively in three patients. Eighty-three traces from 82 patients were available for analysis. Fifty-seven patients had a fall in trace amplitude by more than 25% of the control, 25 by more than 50% and eight by more than 75%.

With an SSEP amplitude loss of 60%, both sensitivity and specificity for the prediction of post-operative neurological injury were optimised at 67 and 81% respectively, with one false negative result.

SSEP rise at completion of spinal reconstruction and highest intraoperative SSEP rise was compared with neurological outcome in the 40 patients with abnormal pre-operative neurology. Neurology improved in all patients in this group who had a trace amplitude more than 60% above the control value at end of operation. None had neurological deterioration. There was no correlation between intraoperative SSEP rise and neurological outcome.

Conclusion: Loss of trace amplitude more than 50% is common during spinal reconstructive surgery after trauma, however a 60% threshold for SSEP fall improves specificity by reducing the rate of false positive results. A trace amplitude 60% above the control value at completion of operation is specific but not sensitive for postoperative neurological improvement.