Aims and methods

We present a review of our use of the Ilizarov apparatus in a non-acute NGO hospital in Cambodia specialising in limb reconstruction. Frames are applied without on table image intensification. A retrospective case-note analysis of Ilizarov apparatus use for all indications was conducted. 53 frames were applied between November 2005 and October 2011. Indications for application were chronic open fracture, osteomyelitis, fracture malunion, infective and non-infective non-union, bone lengthening, primary bone tumour resection, ankle fusion, congenital deformity or pseudarthrosis, chronic hip dislocation, or a combination of the above.

Femoral component fracture is a rarely reported but devastating complication of total knee arthroplasty. It has occurred most frequently with Whiteside Ortholoc II replacements uncemented knee replacements. Presentation may be with acute pain, progressive pain or returning deformity. It occurs more commonly in the medial condyle of the femoral component. It is rarely seen in cemented replacements.

All currently available literature describing fractures of condylar replacements, both cemented and uncemented. Predisposing factors include varus deformity either pre or post operatively. The mechanism of failure is thought to be failure of the infiltration of bone into the replacement. This is often due to polyethylene wear or metallosis causing abnormal tissue reaction with or without osteolysis.

We present the case of a fractured Press Fit Condylar (PFC) cemented implant (DePuy, Johnson&Johnson, Raynham, Massachusettes, USA) affecting the medial condyle. To our knowledge this is only the third reported case of fracture in a PFC implant, and the first in a cemented PFC implant.

Our patient was a 64 year old male who presented with unresolving knee pain post total knee arthroplasty, caused by fatigue fracture of the medial condyle of the femoral component. This was identified as loosening on plain radiographs and replaced with a revision prosthesis with a good post operative result. Given our aging population and with the increase of joint arthroplasty, this case sheds light on a potentially under recognised and increasingly important cause of knee pain following arthroplasty.

Objective

To compare the ability of a new composite bio-absorbable screw and two conventional metal screws to maintain fixation of scaphoid waist-fractures under dynamic loading conditions.

Objective: To compare the ability of a new composite bio-absorbable screw and two conventional metal screws to maintain fixation of scaphoid waist-fractures under dynamic loading conditions.

Methods: Fifteen porcine radial carpi, whose morphology is comparable to that of human scaphoids, were osteotomized at the waist. Specimens were randomized in three groups: those in group I were fixed with a headed metal screw, in group II with a headless tapered metal screw, and in group III with a bio-absorbable composite screw. Each specimen was oriented at 45° and cyclically loaded using four blocks of 1000 cycles, with peak loads of 40, 60, 80 and 100 N, respectively. In case of gross failure the number of cycles to failure was determined. Otherwise, permanent displacement at the fracture site was measured after each loading block from a standardized high-magnification photograph using image analysis software (Roman v1.70, Institute of Orthopaedics, Oswestry). Statistical analysis was by ANOVA and tolerance limits.

Results: Nogross failure occurred. Average displacements after 4000 cycles up to 100N were 0.05mm±0.03SD (headed metal), 0.15mm±0.16SD (headless metal) and 0.29mm±0.11SD (composite) and differed significantly (p< 0.02). Using tolerance limits, the data allowed us to predict that with 95% certainty, displacement in 95% of any sample fixed with a headed metal screw will be below 0.17mm, headless metal screw below 0.84mm, and composite screw below 0.76mm.

Conclusion: Comparing two types of conventional metal screws and a new composite bio-absorbable screw to maintain scaphoid fixation under cyclic loading conditions, we found small average fracture displacements for all three screws. Moreover, even following severe cyclic loading conditions, clinically meaningful displacements of more than 1 mm are highly unlikely for any of the three screws. We therefore conclude that a new bio-absorbable composite screw can serve as an alternative to conventional screws when fixing scaphoid fractures.

Objective: To compare the ability of a new composite bio-absorbable screw and two conventional metal screws to maintain fixation of scaphoid waist-fractures under dynamic loading conditions. Methods: Fifteen porcine radial carpi, whose morphology is comparable to that of human scaphoids, were osteotomized at the waist. Specimens were randomized in three groups: those in group I were fixed with a headed metal screw, in group II with a headless tapered metal screw, and in group III with a bio-absorbable composite screw. Each specimen was oriented at forty-five degrees and cyclically loaded using four blocks of 1000 cycles, with peak loads of 40, 60, 80 and 100 N, respectively. In case of gross failure the number of cycles to failure was determined. Otherwise, permanent displacement at the fracture site was measured after each loading block from a standardized high-magnification photograph using image analysis software (Roman v1.70, Institute of Orthopaedics, Oswestry). Statistical analysis was by ANOVA and tolerance limits.

Results: Nogrossfailureoccurred. Averagedisplacements after 4000 cycles up to 100N were 0.05mm±0.03SD (headed metal), 0.15mm±0.16SD (headless metal) and 0.29mm±0.11SD (composite) and differed significantly (p< 0.02). Using tolerance limits, the data allowed us to predict that with 95% certainty, displacement in 95% of any sample fixed with a headed metal screw will be below 0.17mm, headless metal screw below 0.84mm, and composite screw below 0.76mm.

Conclusion: Comparing two types of conventional metal screws and a new composite bio-absorbable screw to maintain scaphoid fixation under cyclic loading conditions, we found small average fracture displacements for all three screws. Moreover, even following severe cyclic loading conditions, clinically meaningful displacements of more than 1 mm are highly unlikely for any of the three screws. We therefore conclude that a new bio-absorbable composite screw can serve as an alternative to conventional screws when fixing scaphoid fractures.