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.

We scanned 25 left knees in healthy human subjects using MRI. Multiplanar reconstruction software was used to take measurements of the inferior and posterior facets of the femoral condyles and the trochlea.

A ‘basic circle’ can be defined which, in the sagittal plane, fits the posterior and inferior facets of the lateral condyle, the posterior facet of the medial condyle and the floor of the groove of the trochlea. It also approximately fits both condyles in the coronal plane (inferior facets) and the axial plane (posterior facets). The circle fitting the inferior facet of the medial condyle in the sagittal plane was consistently 35% larger than the other circles and was termed the ‘medial inferior circle’. There were strong correlations between the radii of the circles, the relative positions of the centres of the condyles, the width of the condyles, the total knee width and skeletal measurements including height. There was poor correlation between the radii of the circles and the position of the trochlea relative to the condyles.

In summary, the condyles are approximately spherical except for the inferior facet medially, which has a larger radius in the sagittal plane. The size and position of the condyles are consistent and change with the size of the person. However, the position of the trochlea is variable even though its radius is similar to that of the condyles. This information has implications for understanding anterior knee pain and for the design of knee replacements.

Cite this article: Bone Joint J 2014;96-B:1623–30.

Resurfacing of the humeral head is commonly used within the UK to treat osteoarthritis (OA) of the shoulder. We present the results of a small prospective randomised study of this procedure using the Global CAP prosthesis with two different coatings, Porocoat and DuoFix hydroxyapatite (HA). We followed two groups of ten patients with OA of the shoulder for two years after insertion of the prosthesis with tantalum marker beads, recording pain, Constant–Murley and American Shoulder and Elbow Surgeons (ASES) outcome scores, and using radiostereometric analysis to assess migration. The outcomes were similar to those of other series, with significant reductions in pain (p = 0.003) and an improvement in the Constant (p = 0.001) and ASES scores (p = 0.006). The mean migration of the prosthesis three months post-operatively was 0.78 mm (0.51 to 1.69) and 0.72 mm (0.33 to 1.45) for the Porocoat and DuoFix groups, respectively. Analysis of variance indicated that the rate of migration reached a plateau after three months post-operatively in both groups. At follow-up of two years the mean migration was 1 mm (sd 1 (0.25 to 3.32)); in the Porocoat group and 0.8 mm (sd 0.4 (0.27 to 1.45)) in the DuoFix HA group. Significant migration of the prosthesis was seen in one patient who had received an anterior humeral bone graft. This prosthesis was later revised after 2.7 years.

The addition of a coating of HA to the sintered surface does not improve fixation of this prosthesis.

Cite this article: Bone Joint J 2014;96-B:1077–81.

The August 2014 Children’s orthopaedics Roundup³⁶⁰ looks at: Conservative treatment still OK in paediatric clavicular fractures; Femoral anteversion not the usual suspect in patellar inversion; Shoulder dislocation best treated with an operation; Perthes’ disease results in poorer quality of adult life; Physiotherapy little benefit in supracondylar fractures; Congenital vertical talus addressed at the midtarsal joint; Single-sitting DDH surgery worth the effort; and cubitus valgus associated with simple elbow dislocation

Objectives

The aim of this study was to examine whether asymmetric loading influences macrophage elastase (MMP12) expression in different parts of a rat tail intervertebral disc and growth plate and if MMP12 expression is correlated with the severity of the deformity.

Slipped capital femoral epiphysis (SCFE) is relatively common in adolescents and results in a complex deformity of the hip that can lead to femoroacetabular impingement (FAI). FAI may be symptomatic and lead to the premature development of osteoarthritis (OA) of the hip. Current techniques for managing the deformity include arthroscopic femoral neck osteochondroplasty, an arthroscopically assisted limited anterior approach to the hip, surgical dislocation, and proximal femoral osteotomy. Although not a routine procedure to treat FAI secondary to SCFE deformity, peri-acetabular osteotomy has been successfully used to treat FAI caused by acetabular over-coverage. These procedures should be considered for patients with symptoms due to a deformity of the hip secondary to SCFE.

Cite this article: Bone Joint J 2013;95-B:445–51.

We used demineralised bone matrix (DBM) to augment re-attachment of tendon to a metal prosthesis in an in vivo ovine model of reconstruction of the extensor mechanism at the knee. We hypothesised that augmentation of the tendon-implant interface with DBM would enhance the functional and histological outcomes as compared with previously reported control reconstructions without DBM. Function was assessed at six and 12 weeks postoperatively, and histological examination was undertaken at 12 weeks.

A significant increase of 23.5% was observed in functional weight-bearing at six weeks in the DBM-augmented group compared with non-augmented controls (p = 0.004). By 12 weeks augmentation with DBM resulted in regeneration of a more direct-type enthesis, with regions of fibrocartilage, mineralised fibrocartilage and bone. In the controls the interface was predominantly indirect, with the tendon attached to the bone graft-hydroxyapatite base plate by perforating collagen fibres.

The June 2014 Spine Roundup³⁶⁰ looks at: spinal pedicle screws in paediatric patients; improving diagnosis in lumbar spine stenosis; back pain all in the head?; brace three patients, save one scoliosis operation; pedicle screws more often misplaced than one would think; and incidental dural tears usually no problem

Ventral screw osteosynthesis is a common surgical method for treating fractures of the odontoid peg, but there is still no consensus about the number and diameter of the screws to be used. The purpose of this study was to develop a more accurate measurement technique for the morphometry of the odontoid peg (dens axis) and to provide a recommendation for ventral screw osteosynthesis.

Images of the cervical spine of 44 Caucasian patients, taken with a 64-line CT scanner, were evaluated using the measuring software MIMICS. All measurements were performed by two independent observers. Intraclass correlation coefficients were used to measure inter-rater variability.

The mean length of the odontoid peg was 39.76 mm (sd 2.68). The mean screw entry angle α was 59.45° (sd 3.45). The mean angle between the screw and the ventral border of C2 was 13.18° (sd 2.70), the maximum possible mean converging angle of two screws was 20.35° (sd 3.24). The measurements were obtained at the level of 66% of the total odontoid peg length and showed mean values of 8.36 mm (sd 0.84) for the inner diameter in the sagittal plane and 7.35 mm (sd 0.97) in the coronal plane. The mean outer diameter of the odontoid peg was 12.88 mm (sd 0.91) in the sagittal plane and 11.77 mm (sd 1.09) in the coronal plane. The results measured at the level of 90% of the total odontoid peg length were a mean of 6.12 mm (sd 1.14) for the sagittal inner diameter and 5.50 mm (sd 1.05) for the coronal inner diameter. The mean outer diameter of the odontoid peg was 11.10 mm (sd 1.0) in the sagittal plane and 10.00 mm (sd 1.07) in the coronal plane. In order to calculate the necessary screw length using 3.5 mm cannulated screws, 1.5 mm should be added to the measured odontoid peg length when anatomical reduction seems possible.

The cross-section of the odontoid peg is not circular but slightly elliptical, with a 10% greater diameter in the sagittal plane. In the majority of cases (70.5%) the odontoid peg offers enough room for two 3.5 mm cannulated cortical screws.

Cite this article: Bone Joint J 2013;95-B:536–42.

In order to evaluate the relationship between acetabular and proximal femoral alignment in the initiation and evolution of osteoarthritis of the dysplastic hip, the acetabular and femoral angles were calculated geometrically from radiographs of 62 patients with pre-arthrosis and early osteoarthritis. The sum of the lateral opening angle of the acetabulum and the neck-shaft angle was defined as the lateral instability index (LII), and the sum of the anterior opening angle of the acetabulum and the anteversion angle of the femoral neck as the anterior instability index (AII). These two indices were compared in dysplastic and unaffected hips. A total of 22 unilateral hips with pre-arthrosis were followed for at least 15 years to determine whether the two indices were associated with the progression of osteoarthritis.

The LII of the affected hips (197.4 (sd 6.0)) was significantly greater than that of the unaffected hips (1830 (sd 6.9)). A follow-up study of 22 hips with pre-arthrosis showed that only the LII was associated with progression of the disease, and an LII of 196 was the threshold value for this progression.

Coccydynia is a painful disorder characterised by coccygeal pain which is typically exaggerated by pressure. It remains an unsolved mystery because of the perceived unpredictability of the origin of the pain, some psychological traits that may be associated with the disorder, the presence of diverse treatment options, and varied outcomes. A more detailed classification based on the aetiology and pathoanatomy of coccydynia helps to identify patients who may benefit from conservative and surgical management.

This review focuses on the pathoanatomy, aetiology, clinical features, radiology, treatment and outcome of coccydynia.

This study provides recommendations on the position of the implant in reverse shoulder replacement in order to minimise scapular notching and osteophyte formation. Radiographs from 151 patients who underwent primary reverse shoulder replacement with a single prosthesis were analysed at a mean follow-up of 28.3 months (24 to 44) for notching, osteophytes, the position of the glenoid baseplate, the overhang of the glenosphere, and the prosthesis scapular neck angle (PSNA).

A total of 20 patients (13.2%) had a notch (16 Grade 1 and four Grade 2) and 47 (31.1%) had an osteophyte. In patients without either notching or an osteophyte the baseplate was found to be positioned lower on the glenoid, with greater overhang of the glenosphere and a lower PSNA than those with notching and an osteophyte. Female patients had a higher rate of notching than males (13.3% vs 13.0%) but a lower rate of osteophyte formation (22.9% vs 50.0%), even though the baseplate was positioned significantly lower on the glenoid in females (p = 0.009) and each had a similar mean overhang of the glenosphere.

Based on these findings we make recommendations on the placement of the implant in both male and female patients to avoid notching and osteophyte formation.

Cite this article: Bone Joint J 2013;95-B:530–5.

Our aim was to determine the effect of the initial pattern of fracture and the displacement of fragments on the outcome of proximal humeral fractures treated conservatively. We followed 93 consecutive patients prospectively for one year. Final movement and strength were compared with those of the contralateral side. The final American Shoulder and Elbow Society score and the Disabilities of Arm, Shoulder and Hand and Short-Form 36 questionnaires were compared with those provided by the patient on the day of the injury. Radiographs and CT scans with three-dimensional reconstruction were obtained in all patients. The pattern of the fracture and the displacement of individual fragments were analysed and correlated with the final outcome. There were two cases of nonunion and six of avascular necrosis. The majority of the fractures (84 patients; 90%) followed one of the following four patterns: posteromedial (varus) impaction in 50 patients (54%), lateral (valgus) impaction in 13 (14%), isolated greater tuberosity in 15 (16%), and anteromedial impaction fracture in six (6%). Head orientation, impaction of the surgical neck and displacement of the tuberosity correlated strongly with the outcome.

In fractures with posteromedial impaction, a poor outcome was noted as the articular surface displaced inferiorly increasing its distance from the acromion. A poorer outcome was noted as a fractured greater tuberosity displaced medially overlapping with the posterior articular surface. Lateral impaction fractures had a worse outcome than other patterns of fracture.

The December 2012 Trauma Roundup³⁶⁰ looks at: whether tranexamic acid stops bleeding in trauma across the board; antibiotic beads and VAC; whether anaesthetic determines the outcome in surgery for distal radial fractures; high complications in surgery on bisphosphonate-hardened bone; better outcomes but more dislocations in femoral neck fractures; the mythical hip fracture; plate augmentation in nonunion surgery; and SIGN intramedullary nailing and infections.

Most patients with a nightstick fracture of the ulna are treated conservatively. Various techniques of immobilisation or early mobilisation have been studied. We performed a systematic review of all published randomised controlled trials and observational studies that have assessed the outcome of these fractures following above- or below-elbow immobilisation, bracing and early mobilisation. We searched multiple electronic databases, related bibliographies and other studies. We included 27 studies comprising 1629 fractures in the final analysis. The data relating to the time to radiological union and the rates of delayed union and nonunion could be pooled and analysed statistically.

We found that early mobilisation produced the shortest radiological time to union (mean 8.0 weeks) and the lowest mean rate of nonunion (0.6%). Fractures treated with above- or below-elbow immobilisation and braces had longer mean radiological times to union (9.2 weeks, 9.2 weeks and 8.7 weeks, respectively) and higher mean rates of nonunion (3.8%, 2.1% and 0.8%, respectively). There was no statistically significant difference in the rate of non- or delayed union between those treated by early mobilisation and the three forms of immobilisation (p = 0.142 to p = 1.000, respectively). All the studies had significant biases, but until a robust randomised controlled trial is undertaken the best advice for the treatment of undisplaced or partially displaced nightstick fractures appears to be early mobilisation, with a removable forearm support for comfort as required.

Cite this article: Bone Joint J 2013;95-B:952–9.

Slipped upper femoral epiphysis (SUFE) is one of the known causes of cam-type femoroacetabular impingement (FAI). The aim of this study was to determine the proportion of FAI cases considered to be secondary to SUFE-like deformities.

We performed a case–control study on 96 hips (75 patients: mean age 38 years (15.4 to 63.5)) that had been surgically treated for FAI between July 2005 and May 2011. Three independent observers measured the lateral view head–neck index (LVHNI) to detect any SUFE-like deformity on lateral hip radiographs taken in 45° flexion, 45° abduction and 30° external rotation. A control group of 108 healthy hips in 54 patients was included for comparison (mean age 36.5 years (24.3 to 53.9).

The impingement group had a mean LVHNI of 7.6% (16.7% to -2%) versus 3.2% in the control group (10.8% to -3%) (p < 0.001). A total of 42 hips (43.7%) had an index value > 9% in the impingement group versus only six hips (5.5%) in the control group (p < 0.001). The impingement group had a mean α angle of 73.9° (96.2° to 53.4°) versus 48.2° (65° to 37°) in the control group (p < 0.001).

Our results suggest that SUFE is one of the primary aetiological factors for cam-type FAI.

Cite this article: Bone Joint J 2014; 96-B:724–9.

The purpose of this paper is to discuss the risk factors, prevention strategies, classification, and treatment of intra-operative femur fractures sustained during primary and revision total hip arthroplasty.

Back pain is a common symptom in children and adolescents. Here we review the important causes, of which defects and stress reactions of the pars interarticularis are the most common identifiable problems. More serious pathology, including malignancy and infection, needs to be excluded when there is associated systemic illness. Clinical evaluation and management may be difficult and always requires a thorough history and physical examination. Diagnostic imaging is obtained when symptoms are persistent or severe. Imaging is used to reassure the patient, relatives and carers, and to guide management.

Cite this article: Bone Joint J 2014;96-B:717–23.

We retrospectively examined the long-term outcome of 96 asymptomatic hips in 96 patients with a mean age of 49.3 years (16 to 65) who had radiological evidence of femoroacetabular impingement. When surveillance commenced there were 17, 34, and 45 hips with cam, pincer, and mixed impingement, respectively. Overall, 79 hips (82.3%) remained free of osteoarthritis for a mean of 18.5 years (10 to 40). In contrast, 17 hips (17.7%) developed osteoarthritis at a mean of 12 years (2 to 28). No statistically significant difference was found in the rates of development of osteoarthritis among the three groups (p = 0.43). Regression analysis showed that only the presence of idiopathic osteoarthritis of the contralateral diseased hip was predictive of development of osteoarthritis on the asymptomatic side (p = 0.039).

We conclude that a substantial proportion of hips with femoroacetabular impingement may not develop osteoarthritis in the long-term. Accordingly, in the absence of symptoms, prophylactic surgical treatment is not warranted.