Pelvic discontinuity (PD) is a detrimental complication following total hip arthroplasty (THA). The aim of this study was to assess the clinical and radiological results of patients with PD who were revised using a custom-made triflange acetabular component (CTAC).

This is a single centre prospective study of patients with PD following THA who were treated with a CTAC. The Hip Disability and Osteoarthritis Outcome Score (HOOS), modified Oxford Hip Score (mOHS), EurQol five-dimension three-level (EQ-5D-3L) utility, and Numeric Rating Scale (NRS), including visual analogue score (VAS) for pain, were gathered at baseline, and at one- and two-year follow-up. Clinical and radiological complications, including reasons for revisions were registered. Trends over time are described and tested for significance and clinical relevance.

18 females with 22 CTACs were included with a mean age of 73.5 years (SD 7.7). There were significant improvements between baseline and final follow-up in HOOS (p<0.01), mOHS (p<0.01), EQ-5D-3L utility (p<0.01), EQ-5D-3L NRS (p<0.01), VAS pain rest (p<0.01), and VAS pain activity (p<0.01). A minimal clinically important improvement in mOHS and the HOOS was observed in 16 patients (73%) and 14 patients (64%), respectively. Definite healing of the PD was observed in 19 hips (86%). Complications included six cases with broken screws (27%), four cases (18%) with bony fractures, and one case (4.5%) with sciatic nerve paresthesia. One patient with concurrent bilateral PD had revision surgery due to recurrent dislocations. No revision surgery was performed for screw failure or implant breakage.

This is the first prospective assessment in clinical outcome of patients with PD who were treated with a CTAC. We have demonstrated that CTAC in patients with THA acetabular loosening and PD can result in stable constructs with no mechanical failures. Moreover, clinically relevant improvements in health-related quality of life at two years’ follow-up was observed.

Aims

The aim of this study was to assess the clinical and radiological results of patients who were revised using a custom-made triflange acetabular component (CTAC) for component loosening and pelvic discontinuity (PD) after previous total hip arthroplasty (THA).

Locking compression plate is part of a new plate generation requiring an adapted surgical technique and new thinking about commonly used concepts of internal fixation using plates.

They offer a number of advantages in fracture fixation combining angular stability through the use of locking screws with traditional fixation techniques. This makes the implant suitable for poor bone stock and for fractures in metaphyseal areas.

However the system is complex and cases of plate loosening and plate breakage reported by many authors recently, many of these authors believe it is attributed to the choice of inappropriate plate and/or fixation technique rather than to the features of locking compression plate system.

We are reporting 2 cases of plate breakage after using it to fix diaphyseal femoral shaft fractures; in each case we discuss the pitfalls in the fixation method.

The locking plate manual did not highlight the important pitfalls, which was published later on in the literature as guidelines for their clinical application. Careful and detailed attention to the biomechanical principles of locking compression is crucial to the success of implant in fixing fractures in diaphyseal areas.

The patients were reviewed with the aim of determining whether extending the fusion to the sacrum was needed or would affect the pelvic obliquity over the long term.

Twenty-four patients with quadriplegic cerebral palsy, (non-ambulators) aged between 5–23 who underwent corrective surgery for their scoliosis were included in the study

Twelve patients were stabilized to the sacrum (LUQUE-Galveston technique) and 12 to L4 or L5 in the lumbar spine using pedicle screws. The patients were divided into two groups. Group 1 Pelvic obliquity less than 20° – no stabilisation to the pelvis. Group 2 Pelvic obliquity more than 20° – stabilisation to the pelvis.

Group 1 – Patients with pre-operative pelvic obliquity less than 20° maintained their pre-operative pelvic obliquity without significant deterioration (less than 6° change). Group 2 – Patients with pelvic obliquity of 20° or more stabilised to the sacrum maintained or improved their correction until fusion. One patient had a draining sinus six months after the index operation for which removal of metalware (after fusion) was needed. No patient had a non union of the fusion mass.

We believe that patients with a pelvic obliquity of less than 20 degrees at the time of surgery don’t need stabilization to the pelvis. Lumbar pedicle screws give sufficient stability to the distal construct and preserve mobility at the lumbosacral junction. Operative times and blood loss were reduced in those patients not fixed to the pelvis. There appears to be no significant loss of correction of the pelvis obliquity over time.

Cervical Cord Neuropraxia (CCN) and incomplete cord injuries such as Central Cord Syndrome (CCS) are more prevalent in patients with congenitally narrow spinal canals. The aim of this study was to identify if racial groups were over represented in patients with incomplete cord injuries, and if there was an ethnic variation in mid sagittal cervical spine diameter in the general population.

CT scan was used to measure the mid sagittal diameter of the C3 to C7 cervical vertebrae in a group of 166 sequential trauma patients who had CT scans of the cervical spine at Middlemore Hospital. Patient’s race was that declared by the patient. Four different observers used computer digitisation to measure the mid sagittal diameters and mean sagittal diameter for each level. Measurements were compared between races.

Maori cervical spine canals were found to be 1mm smaller than Europeans (P values less than 0.005) whilst Polynesians had on average a 2mm smaller mid sagittal diameter compared to Europeans (all P values less than 0.001).

This study has demonstrated that Polynesians were over represented in the group of patients who experienced CCS or Transient Cervical Neuropraxia. CT scan assessment demonstrated that both Maoris and Polynesians had significantly narrower canals than their European counterparts. The implications of this study are that Maori and Polynesians involve in high impact activities such as rugby may be at increased risk of incomplete or complete spinal cord injuries. There is however no reliable screening tool available for congenital spinal canal stenosis.

Introduction Cervical cord neuropraxia (CCN) and incomplete cord injuries such as central cord syndrome (CCS) are more prevalent in patients with congenitally narrow spinal canals. At Middlemore Hospital, Polynesian and Maori males are frequent in that group of patients who have experienced a single episode of CCN or CCS. The aim of this study was determine if these racial groups were over-represented in patients with incomplete cord injuries, and if there was an ethnic variation in mid-sagittal diameter of the cervical spine in the general population.

Methods A chart review of all patients who experienced either CCS or CCN in the absence of significant fracture dislocation or disc prolapse was performed. The ethnic origin of these patients was noted. CT scan was used to measure the mid-sagittal diameter of the spinal canal from C3 to C7 in a group of 166 sequential trauma patients who had CT scans of the cervical spine at Middlemore Hospital. Patient’s race was that declared by the patient. Four different observers used computer digitisation to measure the mid-sagittal diameters and mean sagittal diameter for each level. Measurements were compared between races.

Results Between 2000 and 2004, eight patients (7 males, 1 female) were noted to have a central cord syndrome or cervical neuropraxia in the absence of fracture dislocation, acute disc prolapse or developmental spinal stenosis. Five patients were Polynesian, two Maori and one European. CT scan assessment of the 166 patients noted Maori cervical spine canals to be 1mm smaller than Europeans (P values less than .005 at all levels of the C-spine) whilst Polynesians had on average 2mm smaller mid-sagittal diameter compared to Europeans (all P values less than 0.001).

Discussion Patients with congenital reduction in spinal canal diameter have an increased risk of transient neuropraxia (Torg J. J Bone Joint Surg. 1996), neurological injury (Matsura P et al. J Bone Joint Surg. 1989) and more significant myelopathy in the presence of trauma (Eismont FJ et. al. Spine 1984). This study demonstrates that Polynesians were over-represented in the group of patients who experienced central cord syndrome or transient cervical neuropraxia. CT scan assessment demonstrated that both Maoris and Polynesians had significantly narrower canals than their European counterparts. Previous studies have demonstrated that South African blacks have significantly narrow mid-sagittal diameter than Caucasians (Taitz C. Clin Anat. 1996). The implications of this study are that Maori and Polynesians involved in high impact activities such as rugby may be at increased risk of incomplete or complete spinal cord injuries. There is however no reliable screening tool available for congenital spinal canal stenosis.

Introduction and Aims: CT is one of the most versatile and useful medical imaging modalities for computer assisted surgery (CAS) and monitoring bone remodelling. However, the high radiation dosage hinders its widespread use. We describe a method for generating smooth and accurate Finite Element (FE) meshes using CT data with reduced radiation exposure.

Method: We have performed serial CT assisted osteodensitometry measurement on seven patients who had a total hip replacement. FE models were generated automatically with cubic Hermite basis functions for both geometry and density. The meshes were fitted to the geometric and density data sets using least square’s fitting. Density was displayed over the surface of the elements using a colour spectrum. The effect of reducing radiation dosage was studied by generating five different types of FE meshes from each patient with different numbers of CT slices. The different mesh types were generated by varying the gap between slices.

Results: The mesh with the smallest number of CT slices used seven CT scans, with the gap between slices of 3cm on average while the mesh with the largest number of slices used 22 scans with the gap of 0.8cm. For the mesh with the largest number of CT slices, the average error after the geometric fitting was less than 0.5mm. The average error for the density fitting was 70.2 mg/ml. When expressed as the percentage to the overall density data range (0 ~ 1500 mg/ml), the average error was 4.7%. Meshes generated with a smaller number of CT slices had larger errors, and this increased as the number of slices used decreased. The error in geometry dropped dramatically (more than 50%) when more than 10 slices were used, whereas the error in density decreased approximately linearly as the number of slices increased. Overall, it was possible to generate realistic and smooth meshes with a geometrical error of less than 1.5mm and a density error less than 7% using 10 CT slices.

Conclusion: One strength of the current study is that we have used cubic Hermite elements, which requires much less information in generating FE meshes without sacrificing too much accuracy. Our study has shown that we can generate realistic and smooth meshes with about 10 CT slices of the proximal femur. This is important to enhance the power of CT in clinical applications.

Introduction and Aims: Little is known about peri-acetabular bone remodelling after insertion of the acetabular cup in total hip arthroplasty. This study was designed to analyse retroacetabular bone changes using quantitative CT-assisted osteodensitometry. This is a new method for a detailed measurement of bone density (BD) changes around the implants.

Method: Prospective cohort study. Operations were performed on 26 consecutive hips (26 patients) using an uncemented prosthesis with alumina-alumina pairing (Cerafit, Ceraver Osteal, France). The average age of patients was 58.4 years. There were 15 men and 11 women. CT investigations were performed within two weeks of surgery and then one year and three years post-operatively. Cancellous, cortical and total bone density (mgCaHA/ml) were assessed using specific software (Impact-Hip, VAMP, Moehrendorf, Germany).

Results: All 26 hips were available for follow-up at one year, seven patients were available at three years. At three-year follow-up we found an 18.4% decrease of cancellous BD proximal to the upper rim of the cup. Cortical BD increased by + 5.2% in this region. Cortical BD decreased ventral to the cup by −5.0% and by −2.3% dorsal to the cup. Of more interest, cancellous BD was observed to decrease by −40.9% in the ventral region and −32.2% in the dorsal region.

Conclusion: We have observed a progressive decrease of cancellous BD after insertion of an uncemented ace-tabular component. These phenomenon could explain the onset of late migration and implant failure of pressfit cups. Only minor changes have been observed in cortical BD. Further investigations are required to define the role of implant design and material in periprosthetic bone remodelling of the acetabulum.

We report a case of septic arthritis of the hip caused by toxigenic Corynebacterium diphtheria in a healthy, immunized child.

A four-year-old boy was admitted to our hospital with a four-day history of right thigh pain, inability to bear weight on the right leg and sore throat of one-day duration.

He was born in New Zealand and had been immunized against diphtheria. On admission he was febrile (37.3°C) with a congested throat. The right hip was flexed and externally rotated. His inflammatory markers were elevated. Aspiration of the hip yielded 8ml of yellow turbid fluid. Gram stain showed gram-positive bacilli. An arthrotomy was performed and the hip drained

Cultures of the aspirate grew Corynebacterium diphtheriae, the toxigenicity confirmed by the national reference laboratory.

The patient was treated with intravenous and oral antibiotics for 6 weeks and he made a full recovery.

Our patient had a history of immunization to diphtheria and this induces a protective level of antibodies against the toxin but does not prevent the bacteria from invading the blood stream and causing infection.

This is to our knowledge the first reported case of septic arthritis caused by toxigenic strain of Corynebacterium diphtheria.

Treatment of displaced intracapsular fracture of the hip by hemiarthroplasty in old patients is generally satisfactory.

Middlemore Hospital’s agreed criteria for hemiarthroplasty were reviewed and tested.

Two hundred and thirty three patients who had hemiarthroplasty for displaced intracapsular fracture neck of femur between June 199- June 2001. All the patients’ data collected from the hospital computer system and then a search started for these patients to review their current status regarding pain and mobility.

Ninety nine patients (42%) were still alive, of them 13 demented, 13 moved or lost and 7 in a wheel chair.

Sixty six patients reviewed for pain and mobility using Sikorski and Barrington scoring criteria for pain and mobility.

Thirteen patients had painful hemiarthroplasty. Clinical notes of the most active group of these patients (7 patients) reviewed individually to identify the causes.

Two patients had revision to total hip joint replacement within 3 months because of technical errors and two patients placed on the waiting list for revision. The rest had deterioration in their general health that made total hip arthroplasty a risky operation for them.

The revision rate was 1.7 %. We concluded that hemiarthroplasty was an acceptable option for these patients. The selection criteria were correct in 98.2% of the cases. Patients who live in their own home will need a careful assessment before deciding on a hemiarthroplasty for them.

Reimers’ hip migration percentage is commonly used to document the extent of subluxation of the hip in children with spasticity. In this study, two measurers, with six months paediatric orthopaedic experience, measured the migration percentage on 44 pelvic radiographs of children with cerebral palsy, aged between two and eight years. Unknown to the measurers, each radiograph was duplicated, giving 22 non-identical radiographs (44 hips) which were measured twice at time 0 and twice six weeks later. The intra-measurer, intra-sessional absolute differences between the first and second measurements ranged from 0% to 23%, with median values of 2.5% to 3.6%. The intra-sessional median absolute differences were not statistically different between the two measurers and measuring sessions (p = 0.42, Kruskal-Wallis test). The inter-sessional absolute differences for measurements made by the same measurers ranged from 0% to 18% with a median absolute difference of 1.7% to 3.2%. Overall, only 5% of the intra-measurer measurement differences, within and between sessions, were above 13%. Repeated measurements by one measurer over time must, therefore, vary by more than 13% in order to be 95% confident of a true change. The inter-measurer error was higher with median absolute differences between the two measurers’ measurements of the same hip of 3.25% to 5% (0% to 26%) and a 95^th upper confidence interval of 21% to 23%. Averaging the four separate measurements over the two sessions reduced the inter-measurer error to a median absolute difference of 2.8%, but did not improve the 95^th upper confidence interval, which measured 22.4%.

Such inter-measurer errors may be clinically unacceptable.

The purpose was to compare the results of two different surgical techniques in the treatment of severe cerebral palsy scoliosis.

This is a retrospective review of 12 consecutive cerebral palsy patients with scoliosis greater than 90 degrees undergoing simultaneous anterior and posterior spinal fusion. The clinical notes were reviewed along with sequential radiographs. Twelve patients were operated on between March 1997 and October 2001. There were 6 patients who had anterior release and fusion followed by posterior fusion from T2 to the sacrum using the Luque-Galveston technique. (Group 1). The other 6 patients had identical surgery but with the addition of anterior instrumentation as well. (Group 2). There was no loss of fixation or metalware failure. There was no pseudarthrosis. One patient died at the time of rod removal for infection 2 years following their index operation.

These results show that a good outcome is achieved in this group of severely affected cerebral palsy patients using either of the techniques described. The addition of anterior instrumentation may make the surgery easier and was not associated with significant increase in complications.

Introduction: Criticism is often made of general practitioners’ referrals to an orthopaedic service in a public hospital. There is often inadequate information about any previous treatment and it is difficult to assess the levels of pain and disability in the individual patient.

Method: A review of 200 referral letters from general practitioners for patients to attend as orthopaedic out-patients has been carried out. One hundred of these patients were from the North Shore Hospital catchment area and the rest were from the Auckland Hospital catchment area. The letters were analysed according to history, previous treatment, results of previous treatment, and investigations including results of blood tests and x-rays.

Results: An analysis of the results showed that, in general, 50% of the patients’ referrals were inadequately documented and, in particular, it was difficult to assess the individual patient’s level of pain and disability relating to the primary orthopaedic problem.

Discussion: It is suggested that referral letters should contain adequate information to start the initial prioritisation of patients to allow those who have the greater need to have access to the limited resources of the public hospital service.