Limb length deficiency, secondary to trauma or infection, is a common reason for referral to our tertiary service. After experiencing troubles with the Intramedullary Skeletal Kinetic Distractor (ISKD), we changed implant to the magnet operated Precice nail. We evaluated the safety and reliability of this novel device and compared it to our early ISKD results. To minimise variables, we selected femurs only. In total, we reviewed medical and radiographic records of 20 cases (8 ISKD, 12 Precise) from 2010–2015. At each postoperative visit, the accuracy and precision of distraction and complications were recorded. Accuracy reflected how close the measured lengthening was to the prescribed distraction at each postoperative visit. Precision reflected how close the repeated measurements were to each other over the course of total lengthening period. No patients were lost to follow-up (1–3.5 years). With the Precice nail (2012–2015), 11/12 were male and 10/12 were caused by trauma. The mean age was 34. Mean total lengthening was 38mm (range, 29–53mm), with an accuracy of 98percnt; and precision of 92percnt;. All patients achieved target lengthening at a rate of 1mm lengthening per day. In one case, the Precice nail fractured and this was revised successfully. With the ISKD group (2010–2012), 8/8 had complications (magnet jamming, nail breakage, equinus contractures and claw toes), with 25percnt; achieving accurate lengthening and precision of 38percnt;. Our results so far have justified our change in implant choice and, in our experience, support the Precice nail as being safe and precise.
In biomaterial engineering the surface of an implant can influence cell differentiation, adhesion and affinity towards the implant. Increased bone marrow derived mesenchymal stromal cell (BMSC) differentiation towards bone forming osteoblasts, on contact with an implant, can improve osteointegration. The process of micropatterning has been shown to improve osteointegration in polymers, but there are few reports surrounding ceramics. The purpose of this study was to establish a co-culture of BMSCs with osteoclast progenitor cells and to observe the response to micropatterned zirconia toughened alumina (ZTA) ceramics with 30 µm diameter pits. The aim was to establish if the pits were specifically bioactive towards osteogenesis or were generally bioactive and would also stimulate osteoclastogenesis that could potentially lead to osteolysis. We demonstrate specific bioactivity of micropits towards osteogenesis with more nodule formation and less osteoclastogenesis. This may have a role when designing ceramic orthopaedic implants.
Leg length discrepancy (LLD) can adversely affect functional outcome and patient satisfaction after total hip arthroplasty. We describe a novel intraoperative technique for femoral component insertion. We aimed to determine if this technique resulted in the desired femoral placement, as templated, and if this was associated with a reduced LLD. A series of fifty consecutive primary total hip replacements were studied. Preoperative digital templating was performed on standardised PA radiographs of the hips by the senior surgeon. The preoperative LLD was calculated and the distance from the superior tip of the greater trochanter to the predicted shoulder of the stem was calculated (GT-S). Intraoperatively, this length was marked on the rasp handle and the stem inserted to the predetermined level by the surgeon. This level corresponded to the tip of the greater trochanter and formed a continuous line to the mark on the rasp handle. Three independent blinded observers measured the GT-S on the postoperative radiographs. We assessed the relationship between the senior author's GT-S (preoperative) and the observers' GT-S (postoperative) using a Person correlation. The observers also measured the preoperative and postoperative LLD, and the inter-observer variability was calculated as the intra-class correlation coefficient. There was a strong correlation of preoperative and postoperative GT-S (R=0.87), suggesting that the stem was inserted as planned. The mean preoperative and postoperative LLD were −4.3 mm (−21.4–4) and −0.9 mm (−9.8–8.6), respectively (p<0.001). This technique consistently minimised LLD in this series. This technique is quick, non-invasive and does not require supplementary equipment.
