Aim: To test the accuracy of implant positioning in using computer navigation in Resurfacing hip arthroplasty

Materials and methods: Brain Lab was used to register 13 cadavers. The component position was fine tuned to a desirable valgus angle. Wire was passed using navigation. The femoral heads were sectioned after insertion of the prosthesis. The measurements from the screen-shots and the transverse sections were analysed using AutoCad®

Results: The Brain lab Registered the femoral heads to 124.91° ± 14.25° (Range 97° −148° ) CCD. The actual neck shaft angles were 126.11° ± 5.33°. The implants were placed in an angulation’s of 131.46° ± 5.27 ° (Range 116° −137° ) and a version of −0.85° ± 2.1° this gave a valgus of 5.91° ± 13.66°. The position of the wire in the isthmus of the neck was −0.52 mm ± 0.69 mm inferior to the centre and 1.7mm ± 1.9 mm posterior to the centre on the transverse sections (n=6). The components were in 8.69° ± 4.95° (n= 6) valgus to the native neck shaft angle. In only 1 hip the femoral head implanted was of the same size as suggested by navigation, in all the rest of the hips the femoral component was of a larger size. This was because it was felt that implanting a smaller size would cause notching of the superolateral neck.

Conclusion: There is a learning curve involved for registering the femoral heads using computer navigation systems, however the navigation gives the surgeon a distinct advantage of being able to choose the point of entry, implant the prosthesis in as valgus position as possible in relation to the femoral head, translate the implant anteriorly and place the peg in the centre of the femoral neck in both the planes. The computer-aided navigation can optimise the component positioning and thereby provide excellent results.

Aim: To test the accuracy of implant positioning in using computer navigation in Resurfacing hip arthroplasty

Materials and methods: Brain Lab was used to register 13 cadavers. The component position was fine tuned to a desirable valgus angle. Wire was passed using navigation. The femoral heads were sectioned after insertion of the prosthesis. The measurements from the screenshots and the transverse sections were analysed using AutoCad

Results: The Brain lab Registered the femoral heads to 124.91° ± 14.25° (Range 97°–148° ) CCD. The actual neck shaft angles were 126.11° ± 5.33°. The implants were placed in an angulation’s of 131.46° ± 5.27 ° (Range 116° –137° ) and a version of –0.85° ± 2.1° this gave a valgus of 5.91° ± 13.66°. The position of the wire in the isthmus of the neck was –0.52 mm ± 0.69 mm inferior to the centre and 1.7mm ± 1.9 mm posterior to the centre on the transverse sections (n=6). The components were in 8.69° ± 4.95° (n= 6) valgus to the native neck shaft angle. In only 1 hip the femoral head implanted was of the same size as suggested by navigation, in all the rest of the hips the femoral component was of a larger size. This was because it was felt that implanting a smaller size would cause notching of the supero-lateral neck.

Conclusion: There is a learning curve involved for registering the femoral heads using computer navigation systems, however the navigation gives the surgeon a distinct advantage of being able to choose the point of entry, implant the prosthesis in as valgus position as possible in relation to the femoral head, translate the implant anteriorly and place the peg in the centre of the femoral neck in both the planes. The computer-aided navigation can optimise the component positioning and thereby provide excellent results.

Introduction: Wrist injuries are common presentations at Accidents and Emergencies. Distal radius fractures are by far the most common. Scaphoid injuries constitute about 60% of carpal injuries. 35% occult wrist fractures are undiagnosed on 2nd visit radiography (50% distal radius/ulna). Moreover 30% patients with significant soft tissue injuries not diagnosed.

Aim: To compare the MRI (magnetic resonance imaging) and bone scans in the diagnosis of X-Ray negative wrist injuries. To functionally score these wrist at the end of 1-year to assess the outcome.

Materials and methods: A prospective study was done in 33 wrists that did not have a fracture wrist detectable on plain X-ray. The MRI and bone scan were done on the same day within 5-7 days after the injury. PD Fat Saturation Axial and Coronal images were undertaken with MRI. Clinical scoring was done after 1 year after the injury to assess the outcome of these injuries.

Results: We detected fractures in 10 wrists on bone scans and 8 fractures on MRI scans. There was a correlation between MRI and bone scan in 5 Cases. We noted 9% (3/33) of false positive cases with bone scan. Bone scans correlated with the site of injury in 10% of cases. 1 fracture was missed in both MRI and bone scan. MRI identified 4 significant soft tissue injuries and capsular edema in 29/33 cases, which were not identified on bone scans. MRI findings showed superior correlation than bone scans with clinical findings on re-examination, which was done following the scans. PRWE (patient rated wrist evaluation) was used to score the outcome of the wrists at the end of 1 year. The patients who had soft tissue or bony damage detected on MRI had significantly higher scores at 1 year of follow-up.

Conclusion: Though bone scan has high sensitivity in diagnosis of fracture, significant soft tissue injuries will be missed. On the other hand, MRI had a high sensitivity and specificity in diagnosis of a fracture and soft tissue injuries. MRI can differentiate between a bone edema and a fracture. MRI has a disadvantage of limited exposure. Clinicians must be aware of the limitations of both investigations. Though majority of these injuries do not active intervention apart from plaster or splinting, detection of these injuries is essential to prognosticate the outcome.

Aim: To see the efficacy of white cell scan in the diagnosis of prosthetic joint infections.

Materials and methods: A retrospective study was done from Jan 2001 to Dec 2003 on patients with suspected joint infections after prosthetic joint surgery that had white cell scans. 109 patients were identified. We excluded 13 patients due to lack of proper documentation. The case notes for clinical details, laboratory investigations, radiological investigations were reviewed for this purpose. All the patients who did not have intervention were followed for a year for signs of infection.

Results: After exclusion, of 13 patients, 96 patients were taken into the study. Of these, 44 were males and 52 were females. The age range was from 53 years to 91 years with an average of 76 years. We identified 30 total hip replacements, 61 total knee replacements, 3 shoulder replacements and 2 hemi-arthroplasties. 77 of these were cemented and 19 uncemented. The scan was done on an average of 23 months, with a range of 4 months to 16 years after the surgery. The chief complaint was persistant pain at rest and walking in all patients.11 patients had swelling, 7 had redness. None of the patients had discharge. White cells were raised in 6, ESR was raised in 28, and CRP was raised in 15 patients. Antibiotics were started on clinical grounds in 10 patients of which 4 patients showed no response. Plain X-Rays suggested infection in 5 patients. White cell scan suggested infection in 26 patients. Irrespective of scan report, 28 patients were operated for symptoms. There was surgical evidence of infection in 11 patients and 17 had aseptic loosening. Of the 11 surgically confirmed cases of infection, white cell scan showed infection only in 7 patients.

Infection +ve Infection –ve

Positive White Cell Scan 7 19

Negative White Cell Scan 5 65

The specificity of the WCS is 0.77 and sensitivity is 0.58. The positive predictive value is 0.36, and negative predictive value is 0.92.

Conclusion: White cell scan has a good predictive value for exclusion of prosthetic joint infections it has high false positive rate. However caution must be excised in interpreting the negative scans. Persistent symptoms should not be ignored. We recognise that the limitation of our study is our small sample size.

Aim: To analyse the epidemiology of spinal injuries presented in our tertiary referral centre.

Materials and Methods: 202 patients who sustained traumatic spinal column injury were admitted in our tertiary referral centre from 1999 to mid 2002. The case notes were looked at for epidemiological details.

Results: Of 202 patients, 136 were male and the rest were females. Both in males and females, we found 2 peaks in the age incidence of spinal cord injuries. First peak was noted between the age group of 18–30 years and the second peak was noted above 60 years. We classified the spinal column injuries into upper cervical, lower cervical, thoracic, dorso-lumbar, lumber and sacral. Lower cervical and cervico-dorsal junction fractures constituted 48% of the spectrum of spinal column fractures. Significant soft tissue injury was noted in 12 patients. Multiple level spinal injuries were present in 16 patients (7.9%). Although road traffic accidents were responsible for 32% of the fractures, domestic falls also contributed to 30.6% of the fractures. 50%of these domestic falls occurred in patients above 60 years of age. We classified the falls into two categories; those from a height above 6 feet were classed as severe falls, which occurred in 65.6% of cases. Below this height the falls were classed as low falls. 71% of the patients who sustained low falls were above 60 years. Sporting accidents caused 19.8% of the spinal fractures. 27% of them are due to diving. Significantly self-harm was found to be a cause of spinal fracture in 3 patients. 67.8% (137) of the patients sustained neurological injury. Incomplete spinal cord injury was present in 86 patients and complete injury in 51 patients. Tetraplegia and tetraparesis was noted in 89 patients where as paraplegia and paraparesis was noted in 48 patients. 26 patients required ventilation at the time of admission. 63 patients sustained polytrauma of which chest injury was found in one third of the poly traumatised patients.

Conclusion: From our observations, we find that there is an increasing trend of elderly population who are more susceptible for spinal trauma. Traditional high velocity trauma and high falls though still contribute a significant proportion of spinal injuries, equal proportions of spinal fractures are caused by low falls commonly seen in elderly patients. These epidemiological trends will have implications on treatment, rehabilitation and outcome of spinal injuries.

Aim To assess the outcome of ankle fractures in diabetic patients.

Method The case notes and X-rays of 39 patients with diabetes, who had sustained ankle fractures between 1994–2003, were retrospectively analysed.

Results There were 23 females and 16 males with mean age of 66 years in females and 51 years in males. The fracture was the result of a twisting injury in 37 of 39 patients. The average duration of diabetes prior to the fracture was 9.6 years. Thirty per cent of patients had systemic complications. Twenty patients had insulin dependent and 19 had non-insulin dependent diabetes. Fractures were on the left side in 21 patients. One patient had a Gustilo grade 2 fracture. Two had a single malleolar fracture, 28 had bi-malleolar fractures and the remaining nine had tri-malleolar fractures. Talus shift was present in 26 cases. The average time to surgery is 3.8 days. The mean ASA grade is 2.3. Twenty-one patients were managed operatively, of which seven had an infection. One patient underwent amputation. One had post-operative myocardial infarction. Nineteen were managed conservatively and in this group, four patients had infected pressure sores from the plaster, of which two needed plastic surgery care. One was managed with external fixator and developed osteomyelitis, and persistent talus shift and non-union.

Three patients died within 2 years of fracture due to diabetes-related complications. Union was achieved in 36 cases and 30 of the patients walked independently after union.

Conclusion There is a high complication rate following surgery for fractures of the ankle in diabetic patients, but conservative treatment also carries a significant risk because poor skin condition can lead to pressure sores while in plaster and these may need major plastic interventions.