Aims. Despite limited clinical scientific backing, an additional trochanteric stabilizing plate (TSP) has been advocated when treating unstable trochanteric fractures with a sliding hip screw (SHS). We aimed to explore whether the TSP would result in less post operative fracture motion, compared to SHS alone. Methods. Overall, 31 patients with AO/OTA 31-A2 trochanteric fractures were randomized to either a SHS alone or a SHS with an additional TSP. To compare postoperative fracture motion, radiostereometric analysis (RSA) was performed before and after weightbearing, and then at four, eight, 12, 26, and 52 weeks. With the “after weightbearing” images as baseline, we calculated translations and rotations, including shortening and medialization of the femoral shaft. Results. Similar migration profiles were observed in all directions during the course of healing. At one year, eight patients in the SHS group and 12 patients in the TSP group were available for analysis, finding a clinically non-relevant, and statistically non-significant, difference in total translation of 1 mm (95% confidence interval -4.7 to 2.9) in favour of the TSP group. In line with the migration data, no significant differences in clinical outcomes were found. Conclusion. The TSP did not influence the course of healing or postoperative fracture motion compared to SHS alone. Based on our results, routine use of the TSP in AO/OTA 31-A2 trochanteric fractures cannot be recommended. The TSP has been shown, in biomechanical studies, to increase stability in sliding hip screw constructs in both unstable and intermediate stable trochanteric fractures, but the clinical evidence is limited. This study showed no advantage of the TSP in unstable (AO 31-A2) fractures in elderly patients when fracture movement was evaluated with radiostereometric analysis. Cite this article: Bone Jt Open 2024;5(1):37–45

Objectives. External fixators are the traditional fixation method of choice for contaminated open fractures. However, patient acceptance is low due to the high profile and therefore physical burden of the constructs. An externalised locking compression plate is a low profile alternative. However, the biomechanical differences have not been assessed. The objective of this study was to evaluate the axial and torsional stiffness of the externalised titanium locking compression plate (ET-LCP), the externalised stainless steel locking compression plate (ESS-LCP) and the unilateral external fixator (UEF). Methods. A fracture gap model was created to simulate comminuted mid-shaft tibia fractures using synthetic composite bones. Fifteen constructs were stabilised with ET-LCP, ESS-LCP or UEF (five constructs each). The constructs were loaded under both axial and torsional directions to determine construct stiffness. Results. The mean axial stiffness was very similar for UEF (528 N/mm) and ESS-LCP (525 N/mm), while it was slightly lower for ET-LCP (469 N/mm). One-way analysis of variance (ANOVA) testing in all three groups demonstrated no significant difference (F(2,12) = 2.057, p = 0.171). There was a significant difference in mean torsional stiffness between the UEF (0.512 Nm/degree), the ESS-LCP (0.686 Nm/degree) and the ET-LCP (0.639 Nm/degree), as determined by one-way ANOVA (F(2,12) = 6.204, p = 0.014). A Tukey post hoc test revealed that the torsional stiffness of the ESS-LCP was statistically higher than that of the UEF by 0.174 Nm/degree (p = 0.013). No catastrophic failures were observed. Conclusion. Using the LCP as an external fixator may provide a viable and attractive alternative to the traditional UEF as its lower profile makes it more acceptable to patients, while not compromising on axial and torsional stiffness. Cite this article: B. F. H. Ang, J. Y. Chen, A. K. S. Yew, S. K. Chua, S. M. Chou, S. L. Chia, J. S. B. Koh, T. S. Howe. Externalised locking compression plate as an alternative to the unilateral external fixator: a biomechanical comparative study of axial and torsional stiffness. Bone Joint Res 2017;6:216–223. DOI: 10.1302/2046-3758.64.2000470

Aims

Posterior column plating through the single anterior approach reduces the morbidity in acetabular fractures that require stabilization of both the columns. The aim of this study is to assess the effectiveness of posterior column plating through the anterior intrapelvic approach (AIP) in the management of acetabular fractures.

Aims

Postoperative malalignment of the femur is one of the main complications in distal femur fractures. Few papers have investigated the impact of intraoperative malalignment on postoperative function and bone healing outcomes. The aim of this study was to investigate how intraoperative fracture malalignment affects postoperative bone healing and functional outcomes.

Aim. To quantify the micro-motion at the fracture gap in a tibial fracture model stabilised with an external fixator. Method. A surrogate model of a tibia and a cadaver leg were fractured and stabilised using a two-ring hexapod external fixator. They were tested initially under static loading and then subjected to vibration. Results. The overall stiffness of the cadaver leg was significantly higher than the surrogate model under static loading. This resulted in a significantly higher facture movement in the surrogate model. In the surrogate model there was no significant difference between the displacement applied via the vibrating platform and the fracture movement at the fracture gap. The fracture movement was however found to be statistically lower during vibration in the cadaver leg. Discussion. The significant difference in stiffness seen between the surrogate and cadaveric model is likely due to multiple factors such as the presence of soft tissues and fibula, including the biomechanical differences between the frame constructs. The fracture movement seen at 200N loading in the cadaveric leg was approximately 1mm which corresponds to partial weight bearing and a displacement shown to promote callus formation. During vibration however, the movements were far less suggesting that micromotion would be insufficient to promote healing. It may be proposed that soft tissues can alter the overall stiffness and fracture movement recorded in biomechanical studies investigating the effect of various devices or therapies

Aims

Our objective was to conduct a systematic review and meta-analysis, to establish whether differences arise in clinical outcomes between autologous and synthetic bone grafts in the operative management of tibial plateau fractures.

Aims

The aim of this study was to determine the immediate post-fixation stability of a distal tibial fracture fixed with an intramedullary nail using a biomechanical model. This was used as a surrogate for immediate weight-bearing postoperatively. The goal was to help inform postoperative protocols.

Open reduction and internal fixation of proximal humerus fractures with angular stable plates is, beside antegrade nailing of the humerus, a standard procedure. A retrograde nail has been developed to avoid penetrating the rotator cuff and to avoid opening the fracture side during osteosynthesis. The aim of our biomechanical study was to evaluate if retrograde nailing of proximal humerus fractures is as stable as locking plate osteosynthesis. The biomechanical properties of 2 implants were tested in 11 human fresh frozen cadaveric humeri pairs. The Retron Nail® and the Philos® plate were implanted after osteotomy. All specimens were suspected to axial and torque load for 1000 cycles in a servo pneumatic testing apparatus. The Philos® plate had greater torsion stiffness than the Retron® nail, but we found no significance. The Retron® nail had greater axial stiffness but our findings were not statistically significant. Our study showed, that there are no significant differences between a retrograde nail and locking plate osteosynthesis for proximal humerus fractures concerning axial and torsion deformities. Therefore the retrograde nail is a suitable alternative for fixation of proximal humerus fracture

Introduction. Femoral neck fractures are a large clinical and economical problem. One of the most common fixation options for femoral neck fractures are multiple cancellous screws. A previous clinical study has shown the lack of washers to be the single largest predictor of fixation failure in the treatment of femoral neck fractures with cancellous screws. This finding was somewhat surprising as washers do not prevent the screws from backing out and do not provide any increase resistance to varus collapse. Therefore a follow-up biomechanical study was designed to test this observation. The purpose was to evaluate the maximal insertional torque of screws in osteoporotic bone with and without washers. We hypothesized that the lateral cortex of an osteoporotic proximal femur does not provide sufficient counter resistance for the screw heads to obtain maximum torque upon screw insertion in the femoral head and that the use of washers would increase screw purchase by providing a larger rigid surface area and subsequent higher counter resistance thereby allowing a higher maximal screw insertion torque. Methods. We used eight matched pairs of osteoporotic fresh-frozen human cadaveric femurs (age >70 years, all female). Two screws each were inserted in each femur either with or without a washer and maximal insertional torque was measured using a 50 Nm torque transducer. The testing was performed using a customized device which allowed the torque transducer to apply a constant axial force and torque speed to the screws. A paired Student's t-test was used to compare the maximal screw insertional torque of screws with washers versus screws without washers in matched pairs. Results. Fifteen out of 16 times the maximal screw insertional torque was higher when a washer was used. The average maximal torque with a washer was 5.1 Newtonmeter (Nm) compared to 3.1 Nm without a washer (p<0.001). Conclusion. We conclude that the addition of washers increases the maximal insertion torque of cancellous screws in the treatment of osteoporotic femoral neck fractures by providing counter resistance to the screw heads at an otherwise weak lateral cortex. We have demonstrated that the washer prevents the screw heads from penetrating the lateral cortex and provides for an improved purchase of the screws in the femoral head. As a clinical reference value for interpretation of this data, the limit of torque limiting screw drivers used with locking plates is set between 4 and 6 Nm. Therefore the difference in insertion torques likely represents clinically relevant values. Since there is no apparent disadvantage in the use of washers and they are inexpensive and readily available even in less developed countries, we advocate for their routine use until larger clinical studies disprove their efficacy

Introduction. Traumatized musculoskeletal tissue often exhibits prolonged time to healing, mostly due to low blood flow and innervation. Intermittent Pneumatic Compression (IPC) increases blood flow and decreases thromboembolic event after orthopedic surgery,[1] however little is known about healing effects.[2] We hypothesized that IPC could stimulate tissue repair: 1.) blood flow 2.) nerve ingrowth 3.) tissue proliferation and during immobilisation enhance 4.) biomechanical tissue properties. Methods. Study 1: In 104 male Sprague Dawley (SD) rats the right Achilles tendon was ruptured and the animals freely mobilized. Half the group received daily IPC-treatment, using a pump and cuff over the hindpaw that inflates/deflates cyclicly, 0–55mmHg (Biopress SystemTM, Flexcell Int.), and the other half received sham-treatment. Healing was assessed at 1,3,6 weeks by perfusion-analysis with laser doppler scanner (Perimed, Sweden), histology and biomechanical testing. Study 2: 48 male SD-rats were ruptured as above. Three groups of each 16 rats were either mobilized, immobilized or immobilized with IPC treatment. Immobilization was performed by plaster cast. Healing was assessed at 2 weeks with histology and biomechanical testing. Results. Study 1: At 3 and 6 weeks reperfusion increased by 21% and 23% (p< 0.05) after IPC-treatment, strengthened by the observation of elevated numbers of blood vessels and nerves. Fibroblast density was at all time points significantly increased in the IPC group. At three and six weeks the IPC treated tendons displayed an increased tissue organization confirmed by higher collagen I/III ratio in the IPC group. No differences (p = 0.10) were found regarding biomechanical strength. Study 2: Compared to mobilization, immobilization caused a downregulation (p<0.05) of all biomechanical and histological parameters, eg. maximum force decreased 80% and collagen III occurrence by 83%. However when immobilization was combined with IPC biomechanical and histological healing increased significantly compared to pure immobilization, eg. maximum force increased 63% and collagen III occurrence by 150%. Conclusion. This study demonstrated that IPC treatment can counteract biomechanical and morphological deficits caused by immobilization by enhancing proliferative soft tissue repair. Thus, IPC promotes tissue repair by stimulating tissue perfusion and nerve ingrowth as well as accelerating both fibroblast proliferation and collagen organization

Objectives. For a long time lateral release (LR) was performed as a standard procedure both, for patellofemoral pain syndrome (PFPS) and patellofemoral instability (PFI). However, recent biomechanical studies have shown that LR is not useful for decreasing the lateral force onto the patella, but is increasing not only medial but also lateral PFI. Furthermore, pain on palpation over the lateral patellofemoral joint space can result in patients treated with extensive LR. We postulate that in case of persistent PFI or PFPS after failed LR the reconstruction of the lateral retinaculum as an addition of the reconstruction of the medial patellofemoral ligament (MPFL) is necessary in terms of decreasing medial PFI as well as lateral pain. Materials and Methods. In between 03/07 and 04/09 we have seen a total of 25 patients (20 f, 5 m) with persistent PFI and palpatory pain over the lateral retinaculum due to unsuccessful treatment of PFI with a LR. These patients have undergone revision surgery with an anatomical reconstruction of the released lateral retinaculum in combination with a reconstruction of the medial patellofemoral ligament (MPFL) in an aperture-technique using the gracilis tendon. The average age at time of operation was 26.2 ± 9.8 years. Preoperatively, as well as 6 weeks, 3 months, 6 months, and 12 months postoperatively, clinical examinations were performed and subjective as well as objective scores (Kujala-, Tegner-, IKDC-score) were evaluated. Regarding radiological parameters measurement of patellar tilt and shift was carried out on axial radiographs before and after the operation. Results. During the first twelve months after the operation only one redislocation could be recorded. Pain on palpation over the reconstructed lateral retinaculum was remaining in four patients (16%). Although several patients complained about persistent patellofemoral pain on exertion or after enduring flexion of the knee, all of them reported about an improvement of their pain situation. This fact is reflected in a highly significant improved but still moderate IKDC- (from 46.5 ± 14.9 to 68.9 ± 22.7, p<0.001) and Kujala-score (from 47.7 ± 15.3 to 74.8 ± 24.8, p<0.001) at the one year follow up. As far as sports activity is concerned, a statistically significant improvement of the Tegner-score up to 4.7 ± 2.4 (preoperative 2.3 ± 1.5, p<0.001) could be achieved. The radiological analysis showed a highly significant decrease of both, patellar tilt (from 15.4 ± 6.5 to 10.3 ± 6.2, p<0.001) and patellar shift (from 4.3 ± 3.3 to 2.5 ± 1.3, p=0.002). Conclusions. After one or more unsuccessful previous efforts of stabilizing the patella by LR, the technique performed in this essay leads to a considerable improvement of subjective scores and objective clinical and radiological parameters as well as sports activity

Aims

Dual plating of distal femoral fractures with medial and lateral implants has been performed to improve construct mechanics and alignment, in cases where isolated lateral plating would be insufficient. This may potentially compromise vascularity, paradoxically impairing healing. This study investigates effects of single versus dual plating on distal femoral vascularity.

Comminuted and displaced fractures of the inferior pole of the patella are not easy to reduce and it is difficult to fix the fragments soundly enough to allow early movement of the knee. We have evaluated the clinical effectiveness of the separate vertical wiring technique in acute comminuted fractures of the inferior pole of the patella. A biomechanical study was also performed using ten pairs of embalmed cadaver knees. A four-part fracture was made on the inferior pole of the patella and fixed by two separate vertical wires on one side and two pull-out sutures after partial patellectomy on the other. The ultimate load to failure in the first group was significantly higher than in the second (250.1± 109.7 N v 69.7 ± 18.9 N, p< 0.002), as was the stiffness (279.9 ± 76.4 N/mm v 23.2 ± 11.4 N/mm, p< 0.001). The separate wire technique was used in 25 patients with comminuted fractures of the inferior pole of the patella who were followed up for a mean period of 22 months (10 to 50). All the fractures healed at a mean of seven weeks (6 to 10). No breakage of a wire or infection occurred. The mean grading at the final follow-up was 29.5 points (27 to 30) using the Böstman method. This technique preserved the length of the patella, fixed the comminuted fragments of the inferior pole and avoided long-term immobilisation of the knee

Objectives. Osteochondral ankle defects (OCDs) mainly occur in a young, active population. In 63% of cases the defect is located on the medial talar dome. Arthroscopic debridement and microfracture is considered the primary treatment for defects up to 15 mm. To treat patients with a secondary OCD of the medial talar dome, a 15-mm diameter metal implant (HemiCAP ®) was developed. The set of 15 offset sizes was designed to correspond with the anatomy of various talar dome curvatures. Recently, two independent biomechanical cadaver studies were published, providing rationale for clinical use. The present study was undertaken to evaluate the clinical effectiveness and safety of the metal implantation technique for osteochondral lesions of the medial talar dome in a prospective study. Material and methods. Since October 2007, twenty patients have been treated with the implant. Four patients who did not meet the inclusion criteria and four patients who had less than one-year follow-up at the time of writing were left out of this analysis. Twelve patients are reported with one year (n=8) or two years (n=4) follow-up. All patients had had one or two earlier operations without success. On preoperative CT-scanning, the mean lesion size was 16 × 11 (range, 9–26 × 8–14) mm. Outcome measures were: Numeric Rating Scale pain (NRS) at rest and when walking, Foot Ankle Outcome Score (FAOS), American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score, and clinical and radiographic complications. Data are presented as median and range. The Wilcoxon signed ranks test was used to calculate p-values. Results. All patients recovered well from surgery. The NRS at rest improved from 3 (0–7) preoperatively, to 0.5 (0–4) after 1 year and 1 (0–1) after 2 years follow-up (p < 0.05). The NRS when walking was 6.5 (4–8) preoperatively, improving to 1.5 (0–5) at 1 year and 1 (0–2) at 2 years follow-up (p < 0.05). The five subscales of the FAOS improved from 14–64 preoperatively, to 53–91 after 1 year and 63–100 after 2 years (p < 0.05). The AOFAS improved from 70 (42–75) before surgery to 86 (58–100) at 1 year, and 89 (82–90) at 2 years follow-up (p < 0.05). There were no clinical or radiographic complications. Conclusion. The metallic implantation technique appears to be a promising treatment for secondary OCDs of the talus, but more patients and longer follow-up are necessary to draw firm conclusions

Aims

The best method of treating unstable pelvic fractures that involve the obturator ring is still a matter for debate. This study compared three methods of treatment: nonoperative, isolated posterior fixation and combined anteroposterior stabilization.

Aims

The aim of this study was to investigate the effect of a posterior malleolar fragment (PMF), with < 25% ankle joint surface, on pressure distribution and joint-stability. There is still little scientific evidence available to advise on the size of PMF, which is essential to provide treatment. To date, studies show inconsistent results and recommendations for surgical treatment date from 1940.

Aims

The aim of this paper is to review the evidence relating to the anatomy of the proximal femur, the geometry of the fracture and the characteristics of implants and methods of fixation of intertrochanteric fractures of the hip.

We investigated a new intramedullary locking nail that allows the distal interlocking screws to be locked to the nail. We compared fixation using this new implant with fixation using either a conventional nail or a locking plate in a laboratory simulation of an osteoporotic fracture of the distal femur. A total of 15 human cadaver femora were used to simulate an AO 33-A3 fracture pattern. Paired specimens compared fixation using either a locking or non-locking retrograde nail, and using either a locking retrograde nail or a locking plate. The constructs underwent cyclical loading to simulate single-leg stance up to 125 000 cycles. Axial and torsional stiffness and displacement, cycles to failure and modes of failure were recorded for each specimen. When compared with locking plate constructs, locking nail constructs had significantly longer mean fatigue life (75 800 cycles (sd 33 900) vs 12 800 cycles (sd 6100); p = 0.007) and mean axial stiffness (220 N/mm (sd 80) vs 70 N/mm (sd 18); p = 0.005), but lower mean torsional stiffness (2.5 Nm/° (sd 0.9) vs 5.1 Nm/° (sd 1.5); p = 0.008). In addition, in the nail group the mode of failure was either cut-out of the distal screws or breakage of nails, and in the locking plate group breakage of the plate was always the mode of failure. Locking nail constructs had significantly longer mean fatigue life than non-locking nail constructs (78 900 cycles (sd 25 600) vs 52 400 cycles (sd 22 500); p = 0.04).

The new locking retrograde femoral nail showed better stiffness and fatigue life than locking plates, and superior fatigue life to non-locking nails, which may be advantageous in elderly patients.

Cite this article: Bone Joint J 2014;96-B:114–21.

It is becoming increasingly common for a patient to have ipsilateral hip and knee replacements. The inter-prosthetic (IP) distance, the distance between the tips of hip and knee prostheses, has been thought to be associated with an increased risk of IP fracture. Small gap distances are generally assumed to act as stress risers, although there is no real biomechanical evidence to support this.

The purpose of this study was to evaluate the influence of IP distance, cortical thickness and bone mineral density on the likelihood of an IP femoral fracture.

A total of 18 human femur specimens were randomised into three groups by bone density and cortical thickness. For each group, a defined IP distance of 35 mm, 80 mm or 160 mm was created by choosing the appropriate lengths of component. The maximum fracture strength was determined using a four-point bending test.

The fracture force of all three groups was similar (p = 0.498). There was a highly significant correlation between the cortical area and the fracture strength (r = 0.804, p <  0.001), whereas bone density showed no influence.

This study suggests that the IP distance has little influence on fracture strength in IP femoral fractures: the thickness of the cortex seems to be the decisive factor.

Cite this article: Bone Joint J 2014;96-B:1378–84.

The spiral blade modification of the Dynamic Hip Screw (DHS) was designed for superior biomechanical fixation in the osteoporotic femoral head. Our objective was to compare clinical outcomes and in particular the incidence of loss of fixation.

In a series of 197 consecutive patients over the age of 50 years treated with DHS-blades (blades) and 242 patients treated with conventional DHS (screw) for AO/OTA 31.A1 or A2 intertrochanteric fractures were identified from a prospectively compiled database in a level 1 trauma centre. Using propensity score matching, two groups comprising 177 matched patients were compiled and radiological and clinical outcomes compared. In each group there were 66 males and 111 females. Mean age was 83.6 (54 to 100) for the conventional DHS group and 83.8 (52 to 101) for the blade group.

Loss of fixation occurred in two blades and 13 DHSs. None of the blades had observable migration while nine DHSs had gross migration within the femoral head before the fracture healed. There were two versus four implant cut-outs respectively and one side plate pull-out in the DHS group. There was no significant difference in mortality and eventual walking ability between the groups. Multiple logistic regression suggested that poor reduction (odds ratio (OR) 11.49, 95% confidence intervals (CI) 1.45 to 90.9, p = 0.021) and fixation by DHS (OR 15.85, 95%CI 2.50 to 100.3, p = 0.003) were independent predictors of loss of fixation.

The spiral blade design may decrease the risk of implant migration in the femoral head but does not reduce the incidence of cut-out and reoperation. Reduction of the fracture is of paramount importance since poor reduction was an independent predictor for loss of fixation regardless of the implant being used.

Cite this article: Bone Joint J 2015;97-B:398–404.