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Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_IV | Pages 139 - 139
1 Mar 2012
Richards A Knight T Belkoff S
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Avulsion fractures of the tip of the olecranon are a common traumatic injury. Kirshner-wire fixation (1.6mm) with a figure of eight tension band wire (1.25mm) remains the most popular technique. Hardware removal mat be required in up to 80% of cases. Modern suture materials have very high tensile strength coupled with excellent usability. In this study we compare a repair using 1.6mm k-wires with a 1.25mm surgical steel, against a repair that uses two strands of 2 fibrewire.

Twelve Pairs of cadaveric arms were harvested. A standard olecranon osteotomy was performed to mimic an avulsion fracture. In each pair one was fixed using standard technique, 2 × 1.6mm transcortical ?-wire plus figure of 8 loop of 1.25mm wire. The other fixed with the same ?-wires with a tension band suture of 2.0 fibrewire (two loops, one figure of 8 and one simple loop). The triceps tendon was cyclically loaded (10-120 Newtons) to simulate full active motion 2200 cycles. Fracture gap was measured with the ‘Smart Capture’ motion analysis system. The arm was fixed at 90 degrees and triceps tendon was loaded until fixation failure, ultimate load to failure and mode of failure was noted.

The average gap formation at the fracture site for the suture group was 0.91mm, in the wire group 0.96mm, no specimen in either group produced a significant gap after cyclical loading. Mean load to failure for the suture group was 1069 Newtons (SD=120N) and in the wire group 820 Newtons (SD=235N).

Both types of fixation allow full early mobilisation without gap formation. The Suture group has a significantly higher load to failure (p=0.002, t-test). Tension Band suture allows a lower profile fixation, potentially reducing the frequency of wound complications and hardware removal.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_II | Pages 283 - 283
1 May 2010
Dinah A Mears S Knight T Soin S Campbell J Belkoff S
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Aim: While ankle fractures are not thought of as osteoporotic fractures, poor bone quality presents difficulties in fracture fixation of the distal fibula. We measured the relation between bone density of the distal fibula and the insertional and stripping torques of screws used for fibular plating using two different plate configurations.

Methods: Ten paired fresh cadaveric ankles (average age: 81.7 years) were used for the study. Computed tomography scanning with phantoms of known density was used to determine the bone density along the distal fibula. A standard small fragment seven-hole one-third tubular plate was applied to the lateral surface of the fibula, with three proximal bicortical cortical screws and two distal unicortical cancellous screws. A posterior plate in which all five screws were cortical and achieved bi-cortical purchase was subsequently applied to the same bones such that the screw holes did not overlap. A torque sensor was used to measure the torque of each screw during insertion (Ti) and then stripping (Ts).

Results: Mean bone density of the distal fibula is significantly less than in the shaft (p< 0.01). There was a moderate positive correlation between torque and bone density for the lateral plates (r2=0.6 for Ti and r2=0.7 for Ts), and a weak correlation for the posterior plates (r2=0.4 for Ti and Ts). For the proximal three screws, there was no significant difference in average Ti and Ts between lateral and posterior plates. For the distal two screws, posterior plates had significantly higher values for both Ti and Ts than the lateral plates (p< 0.01).

Conclusions: The insertion and stripping torques of the screws in the distal fibula were significantly higher and less dependent on bone density with a posterior plate than with a lateral plate.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_III | Pages 357 - 357
1 Sep 2005
Howie D Wimhurst J Wallace R Knight T McGee M Costi K
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Introduction and Aims: This paper presents a treatment plan for femoral stem revision that has been developed based on long-term studies of revision total hip replacement (THR) using cemented stems, cementless proximal fixation stems, cemented stems with impaction grafting and modular titanium long stems.

Method: The clinical and radiographic results of femoral stem revision were compared using the following techniques: 1) a standard or long cemented collarless double taper Exeter or CPT stems (CCDT stems) [n=190]; 2) a proximally porous coated mid to long cementless stem [n=56]; 3) two series of CCDT stems with impaction grafting n=34]; and 4) a modular grit-blasted titanium taper stem [n=13] used for severe cortical damage. Treatment decisions were made based on the age of the patient, the appearance of the pre-operative radiograph and the extent of bone deficiency at surgery. Follow-up was from 17 to two years.

Results: Only one hip was lost to follow-up. In the CCDT group, at a median follow-up of five years (range 2–17 years), two standard length stems and one long stem had been re-revised for loosening (1.5%) and seven stems had been re-revised for other reasons. Survivorship to re-revision for loosening at eight years was 95% (95%CI=85–100%) for both standard and long stems. There was a trend for better longer-term results for long stems. The extent of pre-operative bone loss did not influence results. For the cementless proximal fixation group, at a median follow-up of 10 years, re-revision of the stem for loosening occurred in 20%. Importantly, these poor results could have been predicted from short-term results. The initial series of femoral impaction grafting with CCDT stems and irradiated bone had a small incidence of stem loosening and periprosthetic fracture. The majority of stems subsided, but at a median follow-up of eight years there were no further re-revisions. In the second series, usually with non-irradiated allograft with mesh containment, there was minimal stem subsidence and no re-revision. The grit blasted titanium taper stem has dealt with periprosthetic fratures and severe proximal cortical loss, but with some cases of subsidence and femoral fracture.

Conclusion: Based on these results, our treatment plan for routine femoral revision in middle-aged and elderly patients without severe proximal deficiency is a polished CCDT long stem. In younger patients, impaction grafting is recommended, provided deficient bone is protected. Cementless modular stems are reserved for femurs with severe proximal cortical deficiency.


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_IV | Pages 465 - 465
1 Apr 2004
Howie D Wimhurst J McGee M Knight T Badaruddin B
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Introduction This study reviews the mid to long term results of revision THR with cemented, collarless double-tapered (CCDT) stems.

Methods We prospectively studied 192 revisions, in 183 patients, of femoral stems using standard (42%) or long (58%) Exeter and CPT CCDT stems. Results were analysed according to the length of stem, extent of pre-operative deficiency (Paprosky I:II:IIIa:IIIb:IV = 4:20:44:20:12%) and intra-operative bone loss. Postoperative radiographs were independently analysed for loosening and stress shielding. Risk factors of poor outcome were examined by multivariate logistic regression. The median follow-up was six years (2 to 17 years) with 55 patients having died (28%) and no cases lost to follow-up.

Results There were four stem re-revisions for sepsis (2%), three for aseptic loosening (1.5%) and three for component malpositioning (1.5%). The survivorship to femoral re-revision for aseptic loosening at eight years was 95% (95%CI=90–100%) for standard and 95% (90 – 100%) for long stems (p=0.674). Migration was less than five millimetre in unrevised stems. Survivorship and outcomes was independent of the Paprosky grade. There was a trend for better longer-term results in hips with long stems. Major stress shielding was not seen and thigh pain was not a problem.

Conclusions CCDT long stems are suitable for most femoral revisions in patients without severe segmental deficiency.

In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a non-commercial source.


Orthopaedic Proceedings
Vol. 84-B, Issue SUPP_III | Pages - 264
1 Nov 2002
Holubowycz O Knight T Howie D McGee M
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Reported rates of dislocation after primary and revision total hip replacement (THR) vary widely, whereas subluxation after THR is not commonly reported. Importantly, it is now recognised that reported dislocation rates are likely to be an underestimate of the true dislocation rate. The primary aim of this study was to develop and validate a Patient Hip Instability Questionnaire and subsequently to use this questionnaire to determine the incidence of dislocation, subluxation and symptoms due to hip instability following primary and revision THR. In addition the associated costs, morbidity, disability and effects on health-related quality of life were examined.

A retrospective review of dislocation rates from 1996 to 1998 identified problems in determining the true dislocation rate from standard hospital and database records. Therefore, a patient-completed Hip Instability Questionnaire was developed and validated to monitor dislocation and subluxation rates. This was then mailed to patients three and 12 months following primary or revision THR. All dislocations were then confirmed by telephone interview and radiographs. Telephone interviews and patient completion of the SF-36 questionnaire were used to assess morbidity, disability and quality of life. Costs of treating patients with hip dislocation were also determined.

The response rate to the mailed questionnaire was greater than 95%. The questionnaire was shown to be a valid measure of the true rate of dislocation following THR and confirmed the inaccuracies in previous methods of determining dislocation rate based on hospital and database records. Using this questionnaire, the rate of subluxation was higher than previously reported and the significant morbidity and health care costs associated with with this complication were identified.

The use of this questionnaire will allow better assessment of morbidity and costs due to complications following THR.