Nonunions are a relevant economic burden affecting about 1.9% of all fractures. Rather than specifying a certain time frame, a nonunion is better defined as a fracture that will not heal without further intervention. Successful fracture healing depends on local biology, biomechanics and a variety of systemic factors. All components can principally be decisive and determine the classification of atrophic, oligotrophic or hypertrophic nonunions. Treatment prioritizes mechanics before biology. The degree of motion between fracture parts is the key for healing and is described by strain theory. If the change of length at a given load is > 10%, fibrous tissue and not bone is formed. Therefore, simple fractures require absolute and complex fractures relative stability. The main characteristics of a nonunion are pain while weight bearing, and persistent fracture lines on X-ray. Treatment concepts such as ‘mechanobiology’ or the ‘diamond concept’ determine the applied osteosynthesis considering soft tissue, local biology and stability. Fine wire circular external fixation is considered the only form of true biologic fixation due to its ability to eliminate parasitic motions while maintaining load-dependent axial stiffness. Nailing provides intramedullary stability and biology via reaming. Plates are successful when complex fractures turn into simple nonunions demanding absolute stability. Despite available alternatives, autograft is the gold standard for providing osteoinductive and osteoconductive stimuli. The infected nonunion remains a challenge. Bacteria, especially staphylococcus species, have developed mechanisms to survive such as biofilm formation, inactive forms and internalization. Therefore, radical debridement and specific antibiotics are necessary prior to reconstruction. Cite this article: EFORT Open Rev 2020;5:46-57. DOI: 10.1302/2058-5241.5.190037

Trabecular metal has shown promising results in experimental studies of bone ingrowth. Several clinical studies support these results. However, until now, no randomized clinical radiostereometric analysis (RSA) studies have been published. In this randomized RSA trial, we compared a new acetabular cup with a surface made of tantalum trabecular metal and a cup with a titanium fiber-mesh surface. Between 2004 and 2006, we operated 60 patients with noninflammatory hip arthritis. The patients were randomized to receive either an uncemented cup with a titanium fiber-mesh surface (Trilogy cup) or a cup with a trabecular tantalum surface (Monoblock cup). After 2 years, 50 patients had completed the study. The primary endpoint was cup migration within the first 2 years after surgery; the secondary endpoints were change in bone mineral density and Harris hip score at 3 months. Both cup types showed excellent fixation. RSA revealed minimal translation and rotation at 2 years. There was no statistically significant difference between the cup types with regard to translation. However, less rotation along the transverse axis was seen in the trabecular metal cups than in the fiber mesh cups: mean -0.01º (95% CI: -0.11 to 0.12) for trabecular metal cups and -0.60º (-0.72 to -0.48) for fiber-mesh cups (p = 0.04). The degree of periprosthetic bone loss was similar between the cup types in any of the regions of interest at 2 years of follow-up. 3 months postoperatively, we found a similar increase in Harris hip score in both groups: from around 50 to over 90. We found promising early results concerning fixation of trabecular metal components to the acetabular host bone. However, we recommend a longer observation period to evaluate the outcome of this new cup design.

Purpose: Missed Monteggia fracture dislocation in children is a serious condition. The treatment of this rare condition is controversial and reports on the long-term outcome are sparse. We present a series of patients treated with open reduction and ulnar osteotomy with a mean long-term follow-up of 8 years (range 3–17). Methods: All 16 patients had Bado type 1 (anterior radial head) dislocation. The mean delay from injury to surgery was 17 months (range 1–83). Bilateral radiographs, Oxford Elbow Score, strength measurements, and range of motion were obtained in all patients. Results: There were no major complications to surgery. The radiographic results showed ten patients with reduction of the radial head and with no arthrosis, four patients with arthrosis or subluxation, and two patients with a dislocated radial head. We found a significant correlation between radiographic outcome and delay to ulnar osteotomy ( P = 0.03). Typical clinical findings were a small but significant extension deficit and mean loss of supination of 10° (range 0–90, P < 0.01). Ligament reconstruction or transfixation of the radial head did not influence the radiographic or clinical outcome. Conclusions: Case reports of similar patients treated conservatively demonstrate high morbidity, and, therefore, open reduction and ulnar osteotomy seemed justified. However, this study underlines the importance of minimizing the delay between injury and ulnar osteotomy. If surgery is performed within 40 months after injury, good to fair long-term radiographic results can be obtained. Open reduction and ulnar osteotomy were performed because patients treated conservatively demonstrate high morbidity.

Bone compaction has been shown to increase initial implant fixation. Furthermore, bone compaction creates a peri‐implant zone of autograft that exerts osteoconductive properties. We have previously shown that locally applied bisphosphonate (alendronate) at 4‐week observation can preserve the autograft generated by bone compaction. We now investigate whether the increased amount of autograft, seen at 4 weeks, can increase implant osseointegration and biomechanical fixation. Porous‐coated titanium implants were bilaterally inserted with bone compaction into the proximal part of tibia of 10 dogs. On the right side, local bisphosphonate was injected into the bone cavity prior to bone compaction immediately prior to implant insertion. On the left side, saline was used as control. Observation period was 12 weeks. Locally applied bisphosphonate significantly increased biomechanical implant fixation (approximately twofold), bone‐to‐implant contact (1.2‐fold), and peri‐implant bone volume fraction (2.3‐fold). This study indicates that local alendronate treatment can increase early implant osseointegration and biomechanical fixation of implants inserted by use of bone compaction. Long term effects remain unknown. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:432–441, 2007

It has been shown that fixation of primary cementless joint replacement can independently be enhanced by either: (1) use of hydroxyapatite (HA) coated implants, (2) compaction of the peri‐implant bone, or (3) local application of bisphosphonate. We investigated whether the combined effect of HA coating and bone compaction can be further enhanced with the use of local bisphosphonate treatment. HA‐coated implants were bilaterally inserted into the proximal tibiae of 10 dogs. On one side local bisphosphonate was applied prior to bone compaction. Saline was used as control on the contralateral side. Implants were evaluated with histomorphometry and biomechanical push‐out test. We found that bisphosphonate increased the peri‐implant bone volume fraction (1.3‐fold), maximum shear strength (2.1‐fold), and maximum shear stiffness (2.7‐fold). No significant difference was found in bone‐to‐implant contact or total energy absorption. This study indicates that local alendronate treatment can further improve the fixation of porous‐coated implants that have also undergone HA‐surface coating and peri‐implant bone compaction. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:189–194, 2009

A new surgical technique, compaction, has been shown to improve implant fixation. It has been speculated that the enhanced implant fixation with compaction could be due to a spring-back effect of compacted bone. However, such an effect has yet to be shown. Therefore we investigated in a canine model whether implant cavities prepared with compaction had spring back. Before killing the animals, we used one of two surgical techniques to make implant cavities of identical dimensions in both lateral femoral condyles of 7 dogs. One side had the implant cavity prepared with compaction, the other side with drilling. The cavities were left empty in vivo for 10 minutes before the dogs were killed. Postoperative micro-CT scanning showed that the diameters of the compacted cavities were significantly smaller than those of the drilled cavities, although they had had identical dimensions initially. Thus we found a spring-back effect of compacted bone, which may be important for increasing implant fixation by reducing initial gaps between the implant and bone.