Purpose: Physeal distraction can be used for the treatment of the consequences of epiphysiodesis bridges, correcting simultaneously angular deformations and length discrepancy.

Material and methods: Chondrodiastasis was performed in six children aged 13.1 years (range 10.4–15.7). The cause of the epiphysiodesis was trauma in three children (2 distal tibia, 1 distal radius), osteomyelitis in two (distal femur), and surgical sequela of a clubfoot (distal tibia). Mean follow-up was two years (18 months – 4 years). An Ilizarov device was used in four cases and an Orthofix in two.

Results: Limb length discrepancy was corrected in all cases. Angular correction was insufficient in two. Distraction was continued for four months (1–9) and total duration of treatment was 7.5 months (4–13). Minor complications were pin track infection (n=2) and joint stiffness (n=3). Major complications were one fracture of the femur on a pin site and premature closure of the growth cartilage treated by callotasis and one fracture after removal of the external fixator, treated by plaster cast immobilisation. The final outcome was good in both of these children.

Discussion: De-epiphysiodesis with surgical resection of the bony bridge can only be performed before a certain age (10–11 years) and the outcome in uncertain. The principle advantages of physeal distraction applied for angular deformation in growing patients is that it avoids the need for osteotomy and allows progressive correction. This noninvasive method allows angular correction in the upright patient, concomitant lengthening is also achieved. Chondrodiastasis makes an exact correction of the deformation without resection of the bony bride which can be ruptured by simple distraction. The fertility of the growth cartilage after distraction must be considered as lost so the amount of correction must be calculated on the basis of a complete and definitive postoperative epiphysiodesis.

Conclusion: Chondrodiastasis allows correction of acquired and predictable epiphysiodesis bridges at the apex of the deformation and without direct access. This method can be used for partial epiphysiodesis (less than 50%) in children who have not reached maturity. After distraction, the growth cartilage must be considered as definitively closed.

Purpose: With appropriate software, dual energy x-ray absorptiometry (DEXA) provides a means of measuring periprosthetic bone mineral density (BMD) reliably and reproducibly in a single plane. The current method has been improved since the first reports by MacCarthy in 1991.

Material and methods: Since 1992, two series of total hip arthroplasty femoral prostheses using a ceramic-polyethylene cup with a TA6V4 stem were implanted with cement (group A 25 SAS crystal anatomic stems, 22.2 head) or without cement (group B, 27 Euroform stems with hydroxyapatite surfacing on the upper 2/5, 28 head). The patients were followed prospectively with DEXA to measure BMD in the seven Gruen zones immediately after surgery, at six and twelve months, then every year to last follow-up. Mean follow-up was 74 months (36–166). A visual analogue scale was used for subjective assessment of pain. The clinical Harris score and radiological findings were also recorded.

Results: At last follow-up none of the prostheses had required revision surgery. The Harris score was greater than 90 for both groups (mean 91.4 and 95.4 for groups A and B respectively). Radiologically, there were no progressive lucent lines in the two groups but there were three stable lines (zone V, VII, VII, II) without clinical expression in group A and two (zone II, I) with persistent thigh pain in group B. Two migrations of less than 3 mm were also found in group A and four of more than 3 mm in group B. For the two groups, DEXA showed a diffuse reduction in BMD during the first six months that was statistically significant only for zones I and VII for the Euroform implant and for zone VII for the SAS Crystal implant. There was also a significant difference between the two prostheses for zone I. Modifications were not significant at three years and a last follow-up for the distal regions (II, II, V, VI). For group A (SAS Crystal), the reduction was 5.8% at three years and 5.7% at last follow-up for zone I and 18% at three years and 19% at last follow-up for zone VII. For group B, the reduction was 12.6 at three years and 11.4% at last follow-up for zone I and 17.4% at three years and 21.3% at last follow-up for zone VII.

Discussion: The correlations showed that variations in BMD were independent of the initial bone mineral content, patient age or sex, and were not significantly different between the two cemented or non-cemented implants. Patients with painful thighs (two in group A and six in group B) had a different pattern of BMD over time, showing less pronounced reduction in the proximal zones I and VII and marked bone resorption in zones III and V, an expression of different stress transmission.

Conclusion: This study provided the longest longitudinal radiological and clinical follow-up reported in the literature which, despite the bias introduced by the different types of implants, shows the reliability and reproducibility of DEXA of periprosthetic bone mineral density used to assess implant tolerance and quality of cementing.