Background and purpose — Observing serious adverse events during treatment with the Precice Stryde bone lengthening nail (NuVasive, San Diego, CA, USA), we conducted a nationwide cross-sectional study to report the prevalence of adverse events from all 30 bone segments in 27 patients treated in Denmark. Patients and methods — Radiographs of all bone segments were evaluated regarding radiographic changes in February 2021. We determined the number of bone segments with late onset of pain and/or radiographically confirmed osteolysis, periosteal reaction, or cortical hypertrophy in the junctional area of the nail. Results — In 30 bone segments of 27 patients we observed radiographic changes in 21/30 segments of 20/27 patients, i.e., 19/30 osteolysis, 12/30 periosteal reaction (most often multi-layered), and 12/30 cortical hypertrophy in the area of the junction between the telescoping nail parts. Late onset of pain was a prominent feature in 8 patients. This is likely to be a prodrome to the bony changes. Discoloration (potential corrosion) at the nail interface was observed in multiple removed nails. 15/30 nails were still at risk of developing complications, i.e., were not yet removed. Interpretation — All Stryde nails should be monitored at regular intervals until removal. Onset of pain at late stages of limb lengthening, i.e., consolidation of the regenerate, should warrant immediate radiographic examination regarding osteolysis, periosteal reaction, and cortical hypertrophy, which may be associated with discoloration (potential corrosion) of the nail. We recommend removal of Stryde implants as early as possible after consolidation of the regenerate.

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.

In paediatric orthopaedics, deformities and discrepancies in length of bones are key problems that commonly need to be addressed in daily practice. An understanding of the physiology behind developing bones is crucial for planning treatment. Modulation of the growing bone can be performed in a number of ways. Here, we discuss the principles and mechanisms behind the techniques. Historically, the first procedures were destructive in their mechanism but reversible techniques were later developed with stapling of the growth plate being the gold standard treatment for decades. It has historically been used for both angular deformities and control of overall bone length. Today, tension band plating has partially overtaken stapling but this technique also carries a risk of complications. The diverging screws in these implants are probably mainly useful for hemiepiphysiodesis. We also discuss new minimally invasive techniques that may become important in future clinical practice.

Background In children with angulating deformities of the lower limbs, hemiepiphysiodesis can be used to guide growth to achieve better alignment at skeletal maturity. Traditionally, this has been performed with staples. The tension-band plating technique is new and it has been advocated because it is believed to reduce the risk of premature closure of the growth plate compared to stapling. The benefit of the tension-band plating technique has not yet been proven in experimental or randomized clinical studies.Methods We performed a randomized clinical trial in which 26 children with idiopathic genu valgum were allocated to stapling or tension-band plating hemiepiphysiodesis. Time to correction of the deformity was recorded and changes in angles on long standing radiographs were measured. Pain score using visual analog scale (VAS) was recorded for the first 72 h postoperatively. Analgesics taken were recorded by the parents.Results Mean treatment times for stapling hemiepiphysiodesis (n = 10) and for tension-band plating hemiepiphysiodesis (n = 10) were similar. Postoperative VAS scores and consumption of analgesics were also similar in both groups. No hardware failure or wound-related infection was observed.Interpreatation Treatment time for the 2 treatment modalities was not significantly different in this randomized clinical trial. Tension-band plating and stapling appeared to have a similar effect regarding correction of genu valgum. We cannot rule out type-II error and the possibility that our study was underpowered.ClinicalTrials.gov Identifier: NCT01641354.

Hydroxyapatite (HA) coating of implant surfaces is believed to improve longevity of uncemented total hip arthroplasty (THA). However; it is speculated that HA particles may cause third body wear of the polyethylene (PE) liner with subsequent osteolysis and aseptic loosening of implants. We performed a retrospective comparison of two patient populations with cementless Mallory-Head acetabular components. The patients were identified in the Danish hip arthroplasty Registry (DHR); 77 patients had HA-coated cups and 73 patients had non-HA coated cups. Anteroposterior (AP) radiographs were analysed for PE wear, osteolysis was quantified and survival of the acetabular components was compared. The mean follow-up was 11 years. There were no cup revisions in the HA group and 7 cup revisions in the non-HA group (P<0.01). The reason for revision in all cases was aseptic loosening of both stem and cup. The amount of osteolysis was significantly increased around cups in the non-HA group. The two-dimensional linear PE wear-rate of 0.18 mm/year was higher (P<0.001) in the group with HA coated cups compared with 0.12 mm/year in the group with non-HA coated cups. The mean age was lower (P=0.001) in the HA group (57 years) compared with the non-HA group (63 years). After 11.1 years of follow-up non-HA coated cups had a higher revision rate. Increased PE wear with HA-coated cups did not have a negative influence on the revision rate, but may result in a need for revision surgery over time.