Objectives

Lengthening osteotomies of the calcaneus in children are in general grafted with bone from the iliac crest. Artificial bone grafts have been introduced, however, their structural and clinical durability has not been documented. Radiostereometric analysis (RSA) is a very accurate and precise method for measurements of rigid body movements including the evaluation of joint implant and fracture stability, however, RSA has not previously been used in clinical studies of calcaneal osteotomies. We assessed the precision of RSA as a measurement tool in a lateral calcaneal lengthening osteotomy (LCLO).

We present the validation of a translation into Danish of the Oxford ankle foot questionnaire (OxAFQ). We followed the Isis Pros guidelines for translation and pilot-tested the questionnaire on ten children and their parents. Following modifications we tested the validity of the final questionnaire on 82 children (36 boys and 45 girls) with a mean age of 11.7 years (5.5 to 16.0) and their parents. We tested the reliability (repeatability (test–retest), child–parent agreement, internal consistency), feasibility (response rate, time to completion, floor and ceiling effects) and construct validity. The generic child health questionnaire was used for comparison. We found good internal consistency for the physical and the school and play domains, but lower internal consistency for the emotional domain. Overall, good repeatability was found within children and parents as well as agreement between children and parents. The OxAFQ was fast and easy to complete, but we observed a tendency towards ceiling effects in the school and play and emotional domains. To our knowledge this is the first independent validation of the OxAFQ in any language. We found it valid and feasible for use in the clinic to assess the impact on children’s lives of foot and/or ankle disorders. It is a valuable research tool.

Cite this article: Bone Joint J 2015;97-B:420–6.

Permanent growth arrest of the longer bone is an option in the treatment of minor leg-length discrepancies. The use of a tension band plating technique to produce a temporary epiphysiodesis is appealing as it avoids the need for accurate timing of the procedure in relation to remaining growth. We performed an animal study to establish if control of growth in a long bone is possible with tension band plating. Animals (pigs) were randomised to temporary epiphysiodesis on either the right or left tibia. Implants were removed after ten weeks. Both tibiae were examined using MRI at baseline, and after ten and 15 weeks. The median interphyseal distance was significantly shorter on the treated tibiae after both ten weeks (p = 0.04) and 15 weeks (p = 0.04). On T₁-weighted images the metaphyseal water content was significantly reduced after ten weeks on the treated side (p = 0.04) but returned to values comparable with the untreated side at 15 weeks (p = 0.14). Return of growth was observed in all animals after removal of implants.

Temporary epiphysiodesis can be obtained using tension band plating. The technique is not yet in common clinical practice but might avoid the need for the accurate timing of epiphysiodesis.

Cite this article: Bone Joint J 2013;95-B:855–60.

Background

An increasing number of hip prostheses are inserted without bone cement. Experimental research has shown that hydroxyapatite (HA) coated implants are strongly fixated in the bone, which is believed to reduce the likelihood of prosthetic loosening. However, in recent years, there has been much debate about the role of HA particles in third-body polyethylene (PE) wear and formerly we have shown the revision rate to be high among older-design HA coated cups.

Introduction

Chronic radial head dislocation in children after trauma is a serious condition. Often the dislocation is overseen initially and is a part of the Monteggia fracture complex with anterior bowing of the ulna. Typical complaints are pain, decreased ROM and cubitus valgus. Radial head dysplasia often occurs. The treatment of this condition is debated. Only few series of patients treated with open reduction and ulnar osteotomy exists with long-term follow up. We present a group of rare patients with long-time follow-up treated by only two surgeons through a period of 16 years.

Objectives

The accuracy and precision of two new methods of model-based radiostereometric analysis (RSA) were hypothesised to be superior to a plain radiograph method in the assessment of polyethylene (PE) wear.

Impacted bone allograft is often used in revision joint replacement. Hydroxyapatite granules have been suggested as a substitute or to enhance morcellised bone allograft. We hypothesised that adding osteogenic protein-1 to a composite of bone allograft and non-resorbable hydroxyapatite granules (ProOsteon) would improve the incorporation of bone and implant fixation. We also compared the response to using ProOsteon alone against bone allograft used in isolation. We implanted two non-weight-bearing hydroxyapatite-coated implants into each proximal humerus of six dogs, with each implant surrounded by a concentric 3 mm gap. These gaps were randomly allocated to four different procedures in each dog: 1) bone allograft used on its own; 2) ProOsteon used on its own; 3) allograft and ProOsteon used together; or 4) allograft and ProOsteon with the addition of osteogenic protein-1.

After three weeks osteogenic protein-1 increased bone formation and the energy absorption of implants grafted with allograft and ProOsteon. A composite of allograft, ProOsteon and osteogenic protein-1 was comparable, but not superior to, allograft used on its own.

ProOsteon alone cannot be recommended as a substitute for allograft around non-cemented implants, but should be used to extend the volume of the graft, preferably with the addition of a growth factor.

Introduction/Aims: Initial implant stability is crucial for long-term implant survival. A new surgical technique, compaction, has increased in vivo stability of implants inserted with pressþt. However, gaps often exist in total joint replacements between the implant bone bed and the implant. Therefore, we examined in a gap model whether the compaction technique would increase þxation of hydroxylapatite (HA) implants when compared with the conventional drilling technique. Methods: HA coated titanium implants (diameter 6 mm) were inserted bilaterally in the proximal humerus of 7 dogs for 2 weeks. The implant cavity was randomized to either drilling with an 8 mm drill or to compaction by radial enlarging an initial 5 mm drill hole to 8 mm. Implants were tested to failure by push-out test, and histomorphometry was performed. Data are presented as medians with interquartile range in brackets. The Wilcoxon Signed Ranked Test tested differences between compaction and drilling. P-values < 0.05 were considered signiþcant (*).

Conclusion: In this gap model, compaction signiþcantly increased mechanical and histological þxation of HA coated implants.

We have studied the beneficial effects of a hydroxyapatite (HA) coating on the prevention of the migration of wear debris along the implant-bone interface. We implanted a loaded HA-coated implant and a non-coated grit-blasted titanium alloy (Ti) implant in each distal femoral condyle of eight Labrador dogs. The test implant was surrounded by a gap communicating with the joint space and allowing access of joint fluid to the implant-bone interface. We injected polyethylene (PE) particles into the right knee three weeks after surgery and repeated this weekly for the following five weeks. The left knee received sham injections. The animals were killed eight weeks after surgery. Specimens from the implant-bone interface were examined under plain and polarised light.

Only a few particles were found around HA-coated implants, but around Ti implants there was a large amount of particles. HA-coated implants had approximately 35% bone ingrowth, whereas Ti implants had virtually no bone ingrowth and were surrounded by a fibrous membrane.

Our findings suggest that HA coating of implants is able to inhibit peri-implant migration of PE particles by creating a seal of tightly-bonded bone on the surface of the implant.