Background

Investigations into the response to implant debris tend to concentrate on how a population of cells proliferate in the presence of implant material, and how the regulation of cytokines change. For the problem of cobalt-chromium (CoCr) implants this has been done for osteoblasts and osteoclasts to understand how bone resorption, leading to aseptic loosening, is occurring. However, investigating the formation of the extracellular-matrix (ECM) may give a better indication of the mechanisms occurring. ECM is excreted from cells and is important for adhesion, structure, signaling and growth. Type I collagen is the most abundant protein in the ECM and is known to direct tissue development and is therefore a key part of understanding the mechanism behind aseptic loosening.

Objective

To determine if there is a differing effect between two spinal implant systems on sagittal balance and thoracic kyphosis in adolescent idiopathic scoliosis.

To determine if the use of high density implants (i.e. high proportion of pedicle screws relative to number of spinal levels involved) causes significant loss of thoracic kyphosis and its effect on sagittal balance in adolescent idiopathic scoliosis.

Retrospective analysis of pre and post-operative radiographs to assess sagittal balance and C7-L1 kyphosis angle.

17 patients (16 females, 1 male). All right sided single thoracic curves. All surgery performed by single surgeon (Senior author, ED)

Comparison of pre and post operative sagittal balance and C7-L1 kyphosis angle. Assessment of implant density (i.e. proportion of pedicle screw relative to number of spinal levels involved in correction).

9 patients demonstrated improved sagittal balance following surgery. There was no significant difference (p value 0.83) between the pre and post op C7-L1 kyphosis angle. Mean angle pre op 28.9 (95% CI 20.3 to 37.5). Mean angle post op 29.6 (95% CI 22.2 to 37.0). No correlation identified between sagittal balance correction and kyphosis angle. Metal density ranged from 79-100%.

Although the sample size in this series is modest, high density implants do not significantly affect the kyphosis angle in the operative management of adolescent idiopathic scoliosis in the thoracic spine.

Introduction: Many types of prosthesis are currently used for total knee arthroplasty. Controversy exists as to whether mobile-bearing or fixed-bearing implants make any difference in achieving earlier or better movement, resulting in earlier patient discharge.

Aim: The purpose of our study was to compare the post-operative recovery and early results of 4 different mobile- and fixed-bearing knee implants.

Method: Between 19/7/05 and 15/6/07 202 knees were implanted into 190 patients. Patients were randomly selected for 1 of 4 implants (2 mobile-bearing, 2 fixed-bearing). Outcomes were assessed using the American Knee Society Score (AKSS) and range-of-movement, both pre-operatively and at 1 year post-operatively. Range-of-movement was also recorded on discharge.

Results: No significant difference was shown between the individual implant groups and the actual mean pre-operative and 1 year post-operative AKSS knee or functional scores or the change in knee score. A difference was noted however in the change in functional score between the 2 mobile-bearing knees (p=0.03). No significant difference was found between the 4 individual implants or the type of bearing used (mobile- or fixed-bearing) with regards to gender, age, length of stay or range-of-movement.

Conclusion: The type of implant used does not affect the early or 12 month outcomes in relation to range-of-movement, length of stay or AKSS knee scores.

We performed a retrospective follow-up study investigating the safety and efficacy of an independently constructed non-linked double rod system for anterior column reconstruction.

Our objective was to demonstrate safe and cost effective adaptation of a standard deformity system for use in anterior column reconstruction.

Anterior only surgery in patients requiring corporectomy spares the posterior soft tissue envelope. Corporectomy and neural decompression is followed by insertion of a titanium mesh cage and bone graft. Several non-adaptable implant systems (locking plates and linked-rod constructs) have been validated both in clinical and in-vitro studies and are available to the surgeon. These devices can only be used to address the anterior column and can only span a limited number of spinal segments.

Twenty-two patients have undergone anterior column reconstruction for tumour (8), trauma (11) and infection (3) in our unit are included. Mean follow up was 30.5 months. All had anterior corporectomy and decompression, insertion of a titanium mesh cage and stabilisation with an anterior non-linked dual rod construct (Synthes USS II). Follow-up records and radiographs have been analysed.

Ninety-five percent of patients fused clinically and radiologically on plain radiograph examination. There was no failure of metalwork or deterioration in neurological function following surgery. There were 5 deaths in the study group, 4 from progression of metastatic malignant tumour and one within 30 days of surgery. Three patients have had local malignant disease recurrence, two requiring posterior decompression and one requiring further anterior surgery.

This system is effective and safe. It allows fewer implants to be carried by individual hospitals and thus reduces hospital costs.

Study Design: Prospective cohort study

Objective: To assess the ‘red flag’ symptom of night pain as an indicator for serious disease in patients attending a back pain triage clinic (BPTC).

Summary of Background Data: Although common in patients with known serious pathology, the prevalence of night pain in this population is not known.

Methods: 482 consecutive patients attending BPTC were assessed (including history of frequency and duration of night pain). Clinical examination was performed and demographic data obtained. MRI was performed if indicated according to local guidelines.

Outcome measures: Oswestry (ODI), Visual Analogue Scales (for pain, distress and coping) and Hospital Anxiety Depression (HAD) patient based outcome scores were obtained. Serious pathology was defined as infection or tumour as per AHCPR Guidelines (1994) which state that these symptoms are associated with severe night time pain.

Results: 213 patients had night pain with 90 having pain every night. No serious pathology was identified. Patients with night pain had 4.95 hours continuous sleep (2–7) and were woken 2.5 times/night (0–6). Patients with pain every night exhibited higher ODI and HAD scores than those that did not.

Conclusions: Although it is a significant and disruptive symptom for patients, these results challenge the sensitivity of the presence of night pain per se as a useful diagnostic indicator for serious spinal pathology in a back pain triage clinic.

Objective: To assess the cardiology of continuous ECG of Spinal Surgeons performing complex spinal deformity surgery.

Design: Spinal surgeons were attached to 24 hour tape ECG monitors while performing spinal deformity surgery. Pre op, intra-op and immediate post op assessment were performed.

Subjects: 4 Consultants 1 Spinal Fellow

Outcome measures: ECG changes, Heart Rate variance and Heart Rate

Results: Variability in Heart rate was related to the experience of the surgeon and the case performed.

Heart rate variance was highest in the Consultant with the most recent appointment. Heart rate variance in the Trainee was the lowest. The highest heart rate was achieved when scrubbed supervising the surgical trainee. The surgeons with the highest deformity work load had the lowest intra-operative heart rate

Conclusions: Spinal deformity surgery is stressful to the Consultant performing the case. Experience and case mix affect these findings. The highest stress rate occurs with supervising trainees.

Objective: To determine if a porous, coralline-derived hydroxyapatite block (ProOsteon 500^TM, Interpore, Irvine, CA) is a suitable substitute for tricortical iliac crest autograft in cervical interbody fusion.

Design: A prospective randomised trial with two-year follow-up comparing clinical and radiographic outcomes in patients receiving either iliac crest or hydroxyapatite grafts in cervical interbody fusion.

Subjects: Twenty-nine patients undergoing cervical fusion and anterior plating were randomised to receive either iliac crest (Group I) or hydroxyapatite (Group II) interbody grafts. Fourteen patients (19 grafts) in Group I and twelve patients (18 grafts) in Group II were available for final analysis. Both groups were similar with respect to age, sex, diagnosis and levels fused.

Outcome Measures: The SF-36 and Oswestry Disability Index were used to measure clinical outcome. Post-op and final follow-up radiographs were analysed for graft fragmentation, loss of height, loss of angular alignment and hardware failure to assess structural integrity of the graft. Computed or plain tomography was used to evaluate fusion.

Results: Groups I and II demonstrated improvement in preoperative scores for bodily pain (p=. 016 and. 016 respectively) and physical functioning (p=. 050 and. 016 respectively) at final follow-up. There was no significant difference in SF-36 and Oswestry scores between the two groups. Successful radiographic fusion was similar in both groups (79% in Group I and 76% in Group II). Graft fragmentation occurred in 89% of the hydroxyapatite grafts and 11% of the autografts (p=. 001). Greater than 2mm of graft height and 3° of segmental lordosis were lost in 55% of hydroxyapatite grafts vs. 11% of autografts (p=. 009). One patient in Group II and none in Group I required revision surgery for graft failure. The high rate of early radiographic failure in the hydroxyapatite grafts prompted suspension of further enrolment in the clinical trial.

Conclusions: ProOsteon 500 coralline hydroxyapatite blocks do not possess adequate structural integrity to resist axial loading and maintain disc height or segmental lordosis during cervical interbody fusion.