Aims

Proper preoperative planning benefits fracture reduction, fixation, and stability in tibial plateau fracture surgery. We developed and clinically implemented a novel workflow for 3D surgical planning including patient-specific drilling guides in tibial plateau fracture surgery.

Aims

Frailty greatly increases the risk of adverse outcome of trauma in older people. Frailty detection tools appear to be unsuitable for use in traumatically injured older patients. We therefore aimed to develop a method for detecting frailty in older people sustaining trauma using routinely collected clinical data.

Aims

Periprosthetic fractures (PPFs) following hip arthroplasty are complex injuries. This study evaluates patient demographic characteristics, management, outcomes, and risk factors associated with PPF subtypes over a decade.

We hypothesised that the anterior and posterior walls of the body of the first sacral vertebra could be visualised with two different angles of inlet view, owing to the conical shape of the sacrum. Six dry male cadavers with complete pelvic rings and eight dry sacrums with K-wires were used to study the effect of canting (angling the C-arm) the fluoroscope towards the head in 5° increments from 10° to 55°. Fluoroscopic images were taken in each position. Anterior and posterior angles of inclination were measured between the upper sacrum and the vertical line on the lateral view. Three authors separately selected the clearest image for overlapping anterior cortices and the upper sacral canal in the cadaveric models. The dry bone and K-wire models were scored by the authors, being sure to check whether the K-wire was in or out. In the dry bone models the mean score of the relevant inlet position of the anterior or posterior inclination was 8.875 (standard deviation (. sd. ) 0.35), compared with the inlet position of the opposite inclination of –5.75 (. sd. 4.59). We found that two different inlet views should be used separately to evaluate the borders of the body of the sacrum using anterior and posterior inclination angles of the sacrum, during placement of iliosacral screws. Cite this article: Bone Joint J 2015;97-B:705–10

This randomised study compared outcomes in patients with displaced fractures of the clavicle treated by open reduction and fixation by a reconstruction plate which was placed either superiorly or three-dimensionally. Between 2003 and 2006, 133 consecutive patients with a mean age of 44.2 years (18 to 60) with displaced midshaft fractures of the clavicle were allocated randomly to a three-dimensional (3D) (67 patients) or superior group (66). Outcome measures included the peri-operative outcome index, delayed union, revision surgery and symptoms beyond 16 weeks. CT was used to reconstruct an image of each affected clavicle and Photoshop 7.0 software employed to calculate the percentage of the clavicular cortical area in the sagittal plane. The patients were reviewed clinically and radiographically at four and 12 months after the operation. The superior plate group had a higher rate of delayed union and had more symptomatic patients than the 3D group (p < 0.05). The percentage comparisons of cortical bone area showed that cortical bone in the superior distal segment is thicker than in the inferior segment, it is also thicker in the anterior mid-section than in the posterior (p < 0.05). If fixation of midshaft fractures of the clavicle with a plate is indicated, a 3D reconstruction plate is better than one placed superiorly, because it is consistent with the stress distribution and shape of the clavicle

Aims

Malreduction of the syndesmosis has been reported in up to 52% of patients after fixation of ankle fractures. Multiple radiological parameters are used to define malreduction; there has been limited investigation of the accuracy of these measurements in differentiating malreduction from inherent anatomical asymmetry. The purpose of this study was to identify the prevalence of positive malreduction standards within the syndesmosis of native, uninjured ankles.

We carried out a retrospective review of 47 intra-articular fractures of the calcaneum treated by open reduction and internal fixation in 45 patients by a single surgeon between 1993 and 2001. The fractures were evaluated before operation by plain radiographs and a CT scan using Sanders’ classification. Osteosynthesis involved a lateral approach and the use of the AO calcaneal plate. The mean follow-up was for ten years (7 to 15). Clinical assessment included the American Orthopaedic Foot and Ankle Society Score (AOFAS), the Creighton-Nebraska Score, the Kerr, Prothero, Atkins Score and the SF-36 Health Questionnaire. The radiological evaluation consisted of lateral and axial views of the os calcis. Arthritic changes in the subtalar joint were assessed with an internal oblique view and were graded using the Morrey and Wiedeman scale. There were 18 excellent (38.3%), 17 good (36.2%), three fair (6.3%) and nine poor (19.2%) results. Five patients had a superficial wound infection and five others eventually had a subtalar arthrodesis because of continuing pain. Restoration of Böhler’s angle was associated with a better outcome. The degree of arthritic change in the subtalar joint did not correlate with the outcome scores or Sanders’ classification. Prompt osteosynthesis should be considered for intra-articular fractures of the calcaneum in order to restore the shape of the hindfoot and Böhler’s angle

Aims

Minimally invasive fixation of pelvic fragility fractures is recommended to reduce pain and allow early mobilization. The purpose of this study was to evaluate the outcome of two different stabilization techniques in bilateral fragility fractures of the sacrum (BFFS).

Aims

No randomized comparative study has compared the extensile lateral approach (ELA) and sinus tarsi approach (STA) for Sanders type 2 calcaneal fractures. This randomized comparative study was conducted to confirm whether the STA was prone to fewer wound complications than the ELA.

Skin cover after below-knee amputation has been extensively discussed. We describe the flaps which are commonly used and discuss their vascular basis in the context of the current knowledge of the fasciocutaneous system. An understanding of this vascular system will enable surgeons to plan and shape flaps for surgical exposure and coverage

The risk of articular penetration during tibial nailing is well known, but the incidence of unrecognised damage to joint cartilage has not been described. We have identified this complication in the treatment of tibial fractures, described the anatomical structures at risk and examined the most appropriate site of entry for tibial nailing in relation to the shape of the bone, the design of the nail and the surgical approach. We studied the relationship between the intra-articular structures of the knee and the entry point used for nailing in 54 tibiae from cadavers. The results showed that the safe zone in some bones is smaller than the size of standard reamers and the proximal part of some nails. The structures at risk are the anterior horns of the medial and lateral menisci, the anterior part of the medial and lateral plateaux and the ligamentum transversum. This was confirmed by observations made after nailing 12 pairs of cadaver knees. A retrospective radiological analysis of 30 patients who had undergone tibial nailing identified eight at risk according to the entry point and the size of the nail. Unrecognised articular penetration and damage during surgery were confirmed in four. Although intramedullary nailing has been shown to be a successful method for treating fractures of the tibia, one of the most common problems after bony union is pain in the knee. Unrecognised intra-articular injury of the knee may be one cause of this

Aims

The aim of this study was to evaluate the clinical and radiological outcomes of locking plate fixation, with and without an associated fibular strut allograft, for the treatment of displaced proximal humeral fractures in elderly osteoporotic patients.

Aims

Many authors have reported a shorter treatment time when using trifocal bone transport (TFT) rather than bifocal bone transport (BFT) in the management of long segmental tibial bone defects. However, the difference in the incidence of additional procedures, the true complications, and the final results have not been investigated.

Aims

The anterior pelvic internal fixator is increasingly used for the treatment of unstable, or displaced, injuries of the anterior pelvic ring. The evidence for its use, however, is limited. The aim of this paper is to describe the indications for its use, how it is applied and its complications.

Objectives

The monitoring of fracture healing is a complex process. Typically, successive radiographs are performed and an emerging calcification of the fracture area is evaluated. The aim of this study was to investigate whether different bone healing patterns can be distinguished using a telemetric instrumented femoral internal plate fixator.

Aims

Periprosthetic femoral fractures (PFF) following total hip arthroplasty (THA) are devastating complications that are associated with functional limitations and increased overall mortality. Although cementless implants have been associated with an increased risk of PFF, the precise contribution of implant geometry and design on the risk of both intra-operative and post-operative PFF remains poorly investigated. A systematic review was performed to aggregate all of the PFF literature with specific attention to the femoral implant used.

In order to achieve satisfactory reduction of complex distal humeral fractures, adequate exposure of the fracture fragments and the joint surface is required. Several surgical exposures have been described for distal humeral fractures. We report our experience using the anconeus pedicle olecranon flip osteotomy approach. This involves detachment of the triceps along with a sliver of olecranon, which retains the anconeus pedicle. We report the use of this approach in ten patients (six male, four female) with a mean age of 38.4 years (28 to 51). The mean follow-up was 15 months (12 to 18) with no loss to follow-up. Elbow function was graded using the Mayo Score. The results were excellent in four patients, good in five and fair in one patient. The mean time to both fracture and osteotomy union was 10.6 weeks (8 to 12) and 7.1 weeks (6 to 8), respectively. We found this approach gave reliably good exposure for these difficult fractures enabling anatomical reduction and bicondylar plating without complications.

Cite this article: Bone Joint J 2014;96-B:1252–7.

Background

Approximately half of all hip fractures are displaced intracapsular fractures. The standard treatment for these fractures is either hemiarthroplasty or total hip arthroplasty. The recent National Institute for Health and Care Excellence (NICE) guidance on hip fracture management recommends the use of ‘proven’ cemented stem arthroplasty with an Orthopaedic Device Evaluation Panel (ODEP) rating of at least 3B (97% survival at three years). The Thompsons prosthesis is currently lacking an ODEP rating despite over 50 years of clinical use, likely due to the paucity of implant survival data. Nationally, adherence to these guidelines is varied as there is debate as to which prosthesis optimises patient outcomes.

Exsanguination is the second most common cause of death in patients who suffer severe trauma. The management of haemodynamically unstable high-energy pelvic injuries remains controversial, as there are no universally accepted guidelines to direct surgeons on the ideal use of pelvic packing or early angio-embolisation. Additionally, the optimal resuscitation strategy, which prevents or halts the progression of the trauma-induced coagulopathy, remains unknown. Although early and aggressive use of blood products in these patients appears to improve survival, over-enthusiastic resuscitative measures may not be the safest strategy.

This paper provides an overview of the classification of pelvic injuries and the current evidence on best-practice management of high-energy pelvic fractures, including resuscitation, transfusion of blood components, monitoring of coagulopathy, and procedural interventions including pre-peritoneal pelvic packing, external fixation and angiographic embolisation.

Cite this article: Bone Joint J 2014; 96-B:1143–54.

Several bisphosphonates are now available for the treatment of osteoporosis. Porous hydroxyapatite/collagen (HA/Col) composite is an osteoconductive bone substitute which is resorbed by osteoclasts. The effects of the bisphosphonate alendronate on the formation of bone in porous HA/Col and its resorption by osteoclasts were evaluated using a rabbit model. Porous HA/Col cylinders measuring 6 mm in diameter and 8 mm in length, with a pore size of 100 μm to 500 μm and 95% porosity, were inserted into a defect produced in the lateral femoral condyles of 72 rabbits. The rabbits were divided into four groups based on the protocol of alendronate administration: the control group did not receive any alendronate, the pre group had alendronate treatment for three weeks prior to the implantation of the HA/Col, the post group had alendronate treatment following implantation until euthanasia, and the pre+post group had continuous alendronate treatment from three weeks prior to surgery until euthanasia. All rabbits were injected intravenously with either saline or alendronate (7.5 μg/kg) once a week. Each group had 18 rabbits, six in each group being killed at three, six and 12 weeks post-operatively. Alendronate administration suppressed the resorption of the implants. Additionally, the mineral densities of newly formed bone in the alendronate-treated groups were lower than those in the control group at 12 weeks post-operatively. Interestingly, the number of osteoclasts attached to the implant correlated with the extent of bone formation at three weeks.

In conclusion, the systemic administration of alendronate in our rabbit model at a dose-for-weight equivalent to the clinical dose used in the treatment of osteoporosis in Japan affected the mineral density and remodelling of bone tissue in implanted porous HA/Col composites.

In this study, we describe a morphological classification for greater tuberosity fractures of the proximal humerus. We divided these fractures into three types: avulsion, split and depression. We retrospectively reviewed all shoulder radiographs showing isolated greater tuberosity fractures in a Level I trauma centre between July 2007 and July 2012. We identified 199 cases where records and radiographs were reviewed and included 79 men and 120 women with a mean age of 58 years (23 to 96). The morphological classification was applied to the first 139 cases by three reviewers on two occasions using the Kappa statistic and compared with the AO and Neer classifications. The inter- and intra-observer reliability of the morphological classification was 0.73 to 0.77 and 0.69 to 0.86, respectively. This was superior to the Neer (0.31 to 0.35/0.54 to 0.63) and AO (0.30 to 0.32/0.59 to 0.65) classifications. The distribution of avulsion, split and depression type fractures was 39%, 41%, and 20%, respectively. This classification of greater tuberosity fractures is more reliable than the Neer or AO classifications. These distinct fracture morphologies are likely to have implications in terms of pathophysiology and surgical technique.

Cite this article: Bone Joint J 2014;96-B:646–51.

We identified 11 women with a mean age of 74 years (65 to 81) who sustained comminuted distal radial and ulnar fractures and were treated by volar plating and slight shortening of the radius combined with a primary Sauvé-Kapandji procedure.

At a mean of 46 months (16 to 58), union of distal radial fractures and arthrodesis of the distal radioulnar joint was seen in all patients. The mean shortening of the radius was 12 mm (5 to 18) compared to the contralateral side. Flexion and extension of the wrist was a mean of 54° and 50°, respectively, and the mean pronation and supination of the forearm was 82° and 86°, respectively. The final mean disabilities of the arm, shoulder and hand score was 26 points. According to the Green and O’Brien rating system, eight patients had an excellent, two a good and one a fair result.

The good clinical and radiological results, and the minor complications without the need for further operations related to late ulnar-sided wrist pain, justify this procedure in the elderly patient.

Over a five-year period, adult patients with marginal impaction of acetabular fractures were identified from a registry of patients who underwent acetabular reconstruction in two tertiary referral centres. Fractures were classified according to the system of Judet and Letournel. A topographic classification to describe the extent of articular impaction was used, dividing the joint surface into superior, middle and inferior thirds. Demographic information, hospitalisation and surgery-related complications, functional (EuroQol 5-D) and radiological outcome according to Matta’s criteria were recorded and analysed. In all, 60 patients (57 men, three women) with a mean age of 41 years (18 to 72) were available at a mean follow-up of 48 months (24 to 206). The quality of the reduction was ‘anatomical’ in 44 hips (73.3%) and ‘imperfect’ in 16 (26.7%). The originally achieved anatomical reduction was lost in12 patients (25.8%). Radiologically, 33 hips (55%) were graded as ‘excellent’, 11 (18.3%) as ‘good’, one (1.7%) as ‘fair’ and 15 (25%) as ‘poor’. A total of 11 further operations were required in 11 cases, of which six were total hip replacements.

Univariate linear regression analysis of the functional outcome showed that factors associated with worse pain were increasing age and an inferior location of the impaction. Elevation of the articular impaction leads to joint preservation with satisfactory overall medium-term functional results, but secondary collapse is likely to occur in some patients.

Cite this article: Bone Joint J 2013;95-B:230–8.

We reviewed 59 bone graft substitutes marketed by 17 companies currently available for implantation in the United Kingdom, with the aim of assessing the peer-reviewed literature to facilitate informed decision-making regarding their use in clinical practice. After critical analysis of the literature, only 22 products (37%) had any clinical data. Norian SRS (Synthes), Vitoss (Orthovita), Cortoss (Orthovita) and Alpha-BSM (Etex) had Level I evidence. We question the need for so many different products, especially with limited published clinical evidence for their efficacy, and conclude that there is a considerable need for further prospective randomised trials to facilitate informed decision-making with regard to the use of current and future bone graft substitutes in clinical practice.

Cite this article: Bone Joint J 2013;95-B:583–97.

Introduction

The objective of this study was to determine if a synthetic bone substitute would provide results similar to bone from osteoporotic femoral heads during in vitro testing with orthopaedic implants. If the synthetic material could produce results similar to those of the osteoporotic bone, it could reduce or eliminate the need for testing of implants on bone.

Objectives

To investigate the differences of open reduction and internal fixation (ORIF) of complex AO Type C distal radius fractures between two different models of a single implant type.

Filling the empty holes in peri-articular locking plates may improve the fatigue strength of the fixation. The purpose of this in vitro study was to investigate the effect of plugging the unused holes on the fatigue life of peri-articular distal femoral plates used to fix a comminuted supracondylar fracture model.

A locking/compression plate was applied to 33 synthetic femurs and then a 6 cm metaphyseal defect was created (AO Type 33-A3). The specimens were then divided into three groups: unplugged, plugged with locking screw only and fully plugged holes. They were then tested using a stepwise or run-out fatigue protocol, each applying cyclic physiological multiaxial loads.

All specimens in the stepwise group failed at the 770 N load level. The mean number of cycles to failure for the stepwise specimen was 25 500 cycles (sd 1500), 28 800 cycles (sd 6300), and 26 400 cycles (sd 2300) cycles for the unplugged, screw only and fully plugged configurations, respectively (p = 0.16). The mean number of cycles to failure for the run-out specimens was 42 800 cycles (sd 10 700), 36 000 cycles (sd 7200), and 36 600 cycles (sd 10 000) for the unplugged, screw only and fully plugged configurations, respectively (p = 0.50). There were also no differences in axial or torsional stiffness between the constructs. The failures were through the screw holes at the level of comminution.

In conclusion, filling the empty combination locking/compression holes in peri-articular distal femur locking plates at the level of supracondylar comminution does not increase the fatigue life of the fixation in a comminuted supracondylar femoral fracture model (AO 33-A3) with a 6 cm gap.

A high rate of complications is associated with open reduction and internal fixation of Sanders type 4 fractures of the calcaneum. We assessed the long-term outcome of 83 Sanders type 4 comminuted intra-articular fractures of the calcaneum in 64 patients who underwent non-operative treatment between 1999 and 2005. Each fracture was treated by closed reduction and immobilisation in a long leg cast. Patients were reviewed every three months in the first year, and every six months thereafter. At each visit, the involved ankles were assessed by the American Orthopaedic Foot and Ankle Society (AOFAS) criteria. The degree of fracture healing and the presence of osteoarthritis were assessed.

At a mean follow-up of 51 months (24 to 70) the mean AOFAS score was 72 (52 to 92). Osteoarthritis was scored radiologically using Graves’ classification and was evident in the subtalar joints of 75 ankles (90%) on x-ray and in all ankles on CT scans, of which 20 were grade 0 or 1, 39 grade 2, and 24 grade 3.

A non-operative approach to treating these fractures may be simpler, less expensive, easier to administer with fewer complications, and may be better tolerated than surgery, by many patients.

We describe our early operative experience with a new pelvic reduction frame and the standard of reduction of fractures of the pelvic ring which we achieved in the first 35 consecutive patients, with 34 acute fractures and one nonunion. The pre-operative and immediate post-operative radiographs were measured, using two methods, to find the maximum radiological displacement of the fracture and the quality of the reduction according to the criteria of Tornetta and Matta.

There were 19 vertical shear fractures and 16 compression injuries. The mean age of the patients was 33.5 years (10 to 59) and mean delay to surgery was 4.6 days (0 to 16) in the 34 acute injuries. The mean operative time in isolated procedures was 103.4 minutes (sd 6.5). All but one patient had iliosacral screws implanted, 18 had screws in the anterior column, six had plates at the symphysis pubis and 12 had anterior external fixators. The mean maximum horizontal or vertical displacement was improved from 30.8 mm (sd 2.7) to a mean of 7.1 mm (sd 0.7). The reduction was assessed as excellent in ten patients, good in 18, and fair in the remainder. There was no significant influence on the quality of the reduction caused by obesity (p = 0.34), the type of fracture (p = 0.41) or delay to surgery (p = 0.83).

The frame was shown to be effective, allowing the surgeon to obtain a satisfactory reduction and fixation of acute displaced disruptions of the pelvic ring.

This study aimed to evaluate the use of pin leverage in the reduction of Gartland type III supracondylar fractures of the humerus in children. The study comprised 95 children, who were split into three groups according to the type of method of reduction used. Group 1, had an open reduction, group 2, had closed reduction and percutaneous pin fixation and group 3, the pin leverage technique. Each group was analysed according to the time to surgery, the duration of the procedure, the incidence of complications, and the clinical and radiological outcome.

The mean duration of the operative procedure in groups 1, 2 and 3 was 119 minutes (80 to 235), 57 minutes (20 to 110) and 68 minutes (30 to 90), respectively. At a mean follow-up of 30 months (12 to 63) the clinical results were declared excellent or good in all children and the radiological results intermediate in five patients in group 2. The results of the closed reduction using the pin leverage technique was classified as failure in two children.

Our findings lead us to believe that the pin leverage method of reduction gives good results in the treatment of Gartland type III fractures.

We describe a series of 20 patients with ununited fractures of the femoral neck following neglected trauma or failed primary internal fixation who were seen at a mean of 7.5 months (2 to 18) following injury. Open reduction and internal fixation of the fracture was performed in all patients, together with a myoperiosteal flap on the quadratus femoris muscle pedicle.

Union occurred at a mean of 4.9 months (2 to 10) in all patients. The mean follow-up was for 70 months (14 to 144). There was no further progression in six of seven patients with pre-operative radiological evidence of osteonecrosis of the femoral head. One patient had delayed collapse and flattening of the femoral head ten years after union of the fracture, but remained asymptomatic.

This study demonstrates the orthopaedic application of myoperiosteal grafting for inducing osteogenesis in a difficult clinical situation.

We have studied the effect of shortening of the femoral neck and varus collapse on the functional capacity and quality of life of patients who had undergone fixation of an isolated intracapsular fracture of the hip with cancellous screws. After screening 660 patients at four university medical centres, 70 patients with a mean age of 71 years (20 to 90) met the inclusion criteria. Overall, 66% (46 of 70) of the fractures healed with > 5 mm of shortening and 39% (27 of 70) with > 5° of varus. Patients with severe shortening of the femoral neck had significantly lower short form-36 questionnaire (SF-36) physical functioning scores (no/mild (< 5 mm) vs severe shortening (> 10 mm); 74 vs 42 points, p < 0.001). A similar effect was noted with moderate shortening, suggesting a gradient effect (no/mild (< 5 mm) vs moderate shortening (5 to 10 mm); 74 vs 53 points, p = 0.011). Varus collapse correlated moderately with the occurrence of shortening (r = 0.66, p < 0.001). Shortening also resulted in a significantly lower EuroQol questionnaire (EQ5D) index scores (p = 0.05). In a regression analysis shortening of the femoral neck was the only significant variable predictive of a low SF-36 physical functioning score (p < 0.001).

Several techniques are available for the treatment of displaced fractures of the neck of the radius in children. We report our experience in 14 children treated by indirect reduction and fixation using an elastic stable intramedullary nail. The patients were followed up for a mean of 28 months. One developed asymptomatic avascular necrosis. The rest had excellent results. One had a neuropraxia of the posterior interosseous nerve, which recovered within six weeks. We advocate elastic stable intramedullary nailing for the closed reduction and fixation of these fractures in children.

Our aim was to evaluate the efficacy of a two-level reconstruction technique using subchondral miniscrews for the stabilisation of comminuted posterior-wall marginal acetabular fragments before applying lag screws and a buttress plate to the main overlying posterior fragment. Between 1995 and 2003, 29 consecutive patients with acute comminuted displaced posterior-wall fractures of the acetabulum were treated operatively using this technique.

The quality of reduction measured from three standard plain radiographs was graded as anatomical in all 29 hips. The clinical outcome at a mean follow-up of 35 months (24 to 90) was considered to be excellent in five patients (17%), very good in 16 (55%), good in six (21%) and poor in two (7%). The use of the two-level reconstruction technique appears to provide stable fixation and is associated with favourable results in terms of the incidence of post-traumatic osteoarthritis and the clinical outcome. However, poor results may occur in patients over the age of 55 years.

We describe the results of 287 intra-articular fractures of the calcaneum in 247 patients treated by minimally-invasive reduction and K-wire fixation between 1994 and 2003. There were 210 men (85%) and 37 women (15%). The most common cause of injury was a fall from a height in 237 patients (96%). Fracture classification was based on the method described by Sanders and Essex-Lopresti. All patients were operated on within 21 days of injury and 89% (220) within 48 hours. The reduction was graded as nearly anatomical (less than 2 mm residual articular displacement and satisfactory overall alignment) in 212 (73.9%) fractures.

There were 20 cases (7%) of superficial pin-track infection and five (1.7%) of deep infection. All healed at a mean of 6 weeks (3 to 19). Loss of reduction was observed in 13 fractures (4.5%) and a musculocutaneous flap was needed in three (1%).

The results were evaluated in 176 patients (205 fractures) with a mean age of 44.3 years (13 to 67), available for follow-up at a mean of 43.4 months (25 to 87) using the Creighton-Nebraska Health Foundation Assessment score. The mean score was 83.9 points (63 to 100). There were 29 (16.5%) excellent, 98 (55.7%) good, 26 (14.8%) fair and 23 (13%) poor results. A total of 130 patients (73.9%) were able to return to their original occupation at a mean of 5.6 months (3.2 to 12.5) after the injury.

Semi-open reduction and percutaneous fixation is an effective treatment for displaced intra-articular fractures of the calcaneum.