Objectives

The accuracy and precision of two new methods of model-based radiostereometric analysis (RSA) were hypothesised to be superior to a plain radiograph method in the assessment of polyethylene (PE) wear.

The Cementless Oxford Unicompartmental Knee Replacement (OUKR) was developed to address problems related to cementation, and has been demonstrated in a randomised study to have similar clinical outcomes with fewer radiolucencies than observed with the cemented device. However, before its widespread use it is necessary to clarify contraindications and assess the complications. This requires a larger study than any previously published.

We present a prospective multicentre series of 1000 cementless OUKRs in 881 patients at a minimum follow-up of one year. All patients had radiological assessment aligned to the bone–implant interfaces and clinical scores. Analysis was performed at a mean of 38.2 months (19 to 88) following surgery. A total of 17 patients died (comprising 19 knees (1.9%)), none as a result of surgery; there were no tibial or femoral loosenings. A total of 19 knees (1.9%) had significant implant-related complications or required revision. Implant survival at six years was 97.2%, and there was a partial radiolucency at the bone–implant interface in 72 knees (8.9%), with no complete radiolucencies. There was no significant increase in complication rate compared with cemented fixation (p = 0.87), and no specific contraindications to cementless fixation were identified.

Cementless OUKR appears to be safe and reproducible in patients with end-stage anteromedial osteoarthritis of the knee, with radiological evidence of improved fixation compared with previous reports using cemented fixation.

Cite this article: Bone Joint J 2013;95-B:181–7.

We hypothesised that the use of pulsed electromagnetic field (PEMF) bone growth stimulation in acute scaphoid fractures would significantly shorten the time to union and reduce the number of nonunions in a randomised, double-blind, placebo-controlled multicentre trial. A total of 102 patients (78 male, 24 female; mean age 35 years (18 to 77)) from five different medical centres with a unilateral undisplaced acute scaphoid fracture were randomly allocated to PEMF (n = 51) or placebo (n = 51) and assessed with regard to functional and radiological outcomes (multiplanar reconstructed CT scans) at 6, 9, 12, 24 and 52 weeks. The overall time to clinical and radiological healing did not differ significantly between the active PEMF group and the placebo group. We concluded that the addition of PEMF bone growth stimulation to the conservative treatment of acute scaphoid fractures does not accelerate bone healing.

Cite this article: Bone Joint J 2014; 96-B:1070–6.

Objectives

Acetabular retractors have been implicated in damage to the femoral and obturator nerves during total hip replacement. The aim of this study was to determine the anatomical relationship between retractor placement and these nerves.

Objectives

This systematic review and meta-analysis was conducted to determine the mid- to long-term clinical outcomes for a medial-pivot total knee replacement (TKR) system. The objectives were to synthesise available survivorship, Knee Society Scores (KSS), and reasons for revision for this system.

In Norway total joint replacement after hip dysplasia is reported more commonly than in neighbouring countries, implying a higher prevalence of the condition. We report on the prevalence of radiological features associated with hip dysplasia in a population of 2081 19-year-old Norwegians. The radiological measurements used to define hip dysplasia were Wiberg’s centre-edge (CE) angle at thresholds of < 20° and < 25°, femoral head extrusion index <  75%, Sharp’s angle > 45°, an acetabular depth to width ratio < 250 and the sourcil shape assessed subjectively. The whole cohort underwent clinical examination of their range of hip movement, body mass index (BMI), and Beighton hypermobility score, and were asked to complete the EuroQol (EQ-5D) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). The prevalence of hip dysplasia in the cohort varied from 1.7% to 20% depending on the radiological marker used. A Wiberg’s CE angle <  20° was seen in 3.3% of the cohort: 4.3% in women and 2.4% in men. We found no association between subjects with multiple radiological signs indicative of dysplasia and BMI, Beighton score, EQ-5D or WOMAC. Although there appears to be a high prevalence of hip dysplasia among 19-year-old Norwegians, this is dependent on the radiological parameters applied.

Cite this article: Bone Joint J 2013;95-B:279–85.

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.

Although the importance of sound statistical principles in the design and analysis of data has gained prominence in recent years, biostatistics, the application of statistics to the analysis of biological and medical data, is still a subject which is poorly understood and often mishandled. This review introduces, in the context of orthopaedic research, the terminology and the principles involved in simple data analysis, and outlines areas of medical statistics that have gained prominence in recent years. It also lists and provides an insight into some of the more common errors that occur in published orthopaedic journals and which are frequently encountered at the review stage in papers submitted to the Journal of Bone and Joint Surgery.

There is great variability in acetabular component orientation following hip replacement. The aims of this study were to compare the component orientation at impaction with the orientation measured on post-operative radiographs and identify factors that influence the difference between the two. A total of 67 hip replacements (52 total hip replacements and 15 hip resurfacings) were prospectively studied. Intra-operatively, the orientation of the acetabular component after impaction relative to the operating table was measured using a validated stereo-photogrammetry protocol. Post-operatively, the radiographic orientation was measured; the mean inclination/anteversion was 43° (sd 6°)/ 19° (sd 7°). A simulated radiographic orientation was calculated based on how the orientation would have appeared had an on-table radiograph been taken intra-operatively. The mean difference between radiographic and intra-operative inclination/anteversion was 5° (sd 5°)/ -8° (sd 8°). The mean difference between simulated radiographic and intra-operative inclination/anteversion, which quantifies the effect of the different way acetabular orientation is measured, was 3°/-6° (sd 2°). The mean difference between radiographic and simulated radiographic orientation inclination/anteversion, which is a manifestation of the change in pelvic position between component impaction and radiograph, was 1°/-2° (sd 7°).

This study demonstrated that in order to achieve a specific radiographic orientation target, surgeons should implant the acetabular component 5° less inclined and 8° more anteverted than their target. Great variability (2 sd about ± 15°) in the post-operative radiographic cup orientation was seen. The two equally contributing causes for this are variability in the orientation at which the cup is implanted, and the change in pelvic position between impaction and post-operative radiograph.

Cite this article: Bone Joint J 2014;96-B:1290–7

Damage to the cartilage of the distal radioulnar joint frequently leads to pain and limitation of movement, therefore repair of this joint cartilage would be highly desirable. The purpose of this study was to investigate the fixation of scaffold in cartilage defects of this joint as part of matrix-assisted regenerative autologous cartilage techniques. Two techniques of fixation of collagen scaffolds, one involving fibrin glue alone and one with fibrin glue and sutures, were compared in artificially created cartilage defects of the distal radioulnar joint in a human cadaver. After being subjected to continuous passive rotation, the methods of fixation were evaluated for cover of the defect and pull out force.

No statistically significant differences were found between the two techniques for either cover of the defect or integrity of the scaffold. However, a significantly increased mean pull out force was found for the combined procedure, 0.665 N (0.150 to 1.160) versus 0.242 N (0.060 to 0.730) for glue fixation (p = 0.001).

This suggests that although successful fixation of a collagen type I/III scaffold in a distal radioulnar joint cartilage defect is feasible with both forms of fixation, fixation with glue and sutures is preferable.

Cite this article: Bone Joint J 2014;96-B:508–12.

The use of pulsed electromagnetic fields (PEMF) to stimulate bone growth has been recommended as an alternative to the surgical treatment of ununited scaphoid fractures, but has never been examined in acute fractures. We hypothesised that the use of PEMF in acute scaphoid fractures would accelerate the time to union by 30% in a randomised, double-blind, placebo-controlled, multicentre trial. A total of 53 patients in three different medical centres with a unilateral undisplaced acute scaphoid fracture were randomly assigned to receive either treatment with PEMF (n = 24) or a placebo (n = 29). The clinical and radiological outcomes were assessed at four, six, nine, 12, 24 and 52 weeks.

A log-rank analysis showed that neither time to clinical and radiological union nor the functional outcome differed significantly between the groups. The clinical assessment of union indicated that at six weeks tenderness in the anatomic snuffbox (p = 0.03) as well as tenderness on longitudinal compression of the scaphoid (p = 0.008) differed significantly in favour of the placebo group.

We conclude that stimulation of bone growth by PEMF has no additional value in the conservative treatment of acute scaphoid fractures.

This single-blinded randomised controlled trial investigated whether one design of mobile-bearing (MB) total knee replacement (TKR) has any advantage over a fixed-bearing (FB) design on long-term fixation as measured by radiostereometry. The amount of wear underneath the mobile bearing was also evaluated. A series of 42 knees was randomised to MB or FB tibial components with appropriate polyethylene inserts and followed for between ten and 12 years, or until the death of the patient. The polyethylene in the MB group was superior in that it was gamma-irradiated in inert gas and was calcium-stearate free; the polyethylene in the FB group was gamma-irradiated in air and contained calcium stearate. In theory this should be advantageous to the wear rate of the MB group. At final follow-up the overall mean migration was 0.75 mm (sd 0.76) in the MB group and 0.66 mm (sd 0.4) in the FB group, with the FB group demonstrating more posterior tilt and the MB group more internal rotation. In the FB group there was one revision for aseptic loosening, but none in the MB group. There were no significant differences in clinical or radiological scores.

For the MB group, the mean linear wear rate on the under-surface was 0.026 mm/year (sd 0.014). This was significantly smaller than the wear rate of 0.11 mm/year (sd 0.06) in the MB between femur and polyethylene (p < 0.001). Nevertheless, even in a best-case setting the mobile bearings of this TKR design had no apparent advantage in terms of fixation over the FB knee prosthesis at ten to 12 years. The wear underneath the mobile bearing was small and is unlikely to be clinically relevant.

Femoroacetabular impingement causes pain in the hip in young adults and may predispose to the development of osteoarthritis. Genetic factors are important in the aetiology of osteoarthritis of the hip and may have a role in that of femoroacetabular impingement. We compared 96 siblings of 64 patients treated for primary impingement with a spouse control group of 77 individuals. All the subjects were screened clinically and radiologically using a standardised protocol for the presence of cam and pincer deformities and osteoarthritis.

The siblings of those patients with a cam deformity had a relative risk of 2.8 of having the same deformity (66 of 160 siblings hips versus 23 of 154 control hips, p < 0.00001). The siblings of those patients with a pincer deformity had a relative risk of 2.0 of having the same deformity (43 of 116 sibling hips versus 29 of 154 control hips, p = 0.001). Bilateral deformity occurred more often in the siblings (42 of 96 siblings versus 13 of 77 control subjects, relative risk 2.6, p = 0.0002). The prevalence of clinical features in those hips with abnormal morphology was also greater in the sibling group compared with the control group (41 of 109 sibling hips versus 7 of 46 control hips, relative risk 2.5, p = 0.007). In 11 sibling hips there was grade-2 osteoarthritis according to Kellgren and Lawrence versus none in the control group (p = 0.002).

Genetic influences are important in the aetiology of primary femoroacetabular impingement. This risk appears to be manifested through not only abnormal joint morphology, but also through other factors which may modulate progression of the disease.

The orientation of the acetabular component is influenced not only by the orientation at which the surgeon implants the component, but also the orientation of the pelvis at the time of implantation. Hence, the orientation of the pelvis at set-up and its movement during the operation, are important. During 67 hip replacements, using a validated photogrammetric technique, we measured how three surgeons orientated the patient’s pelvis, how much the pelvis moved during surgery, and what effect these had on the final orientation of the acetabular component. Pelvic orientation at set-up, varied widely (mean (± 2, standard deviation (sd))): tilt 8° (2sd ±32), obliquity –4° (2sd ±12), rotation –8° (2sd ±14). Significant differences in pelvic positioning were detected between surgeons (p < 0.001). The mean angular movement of the pelvis between set-up and component implantation was 9° (sd 6). Factors influencing pelvic movement included surgeon, approach (posterior >  lateral), procedure (hip resurfacing > total hip replacement) and type of support (p < 0.001). Although, on average, surgeons achieved their desired acetabular component orientation, there was considerable variability (2sd ±16) in component orientation. We conclude that inconsistency in positioning the patient at set-up and movement of the pelvis during the operation account for much of the variation in acetabular component orientation. Improved methods of positioning and holding the pelvis are required.

Cite this article: Bone Joint J 2014; 96-B:876–83.

There have been considerable recent advances in the understanding and management of femoroacetabular impingement and associated labral and chondral pathology. We have developed a classification system for acetabular chondral lesions. In our system, we use the six acetabular zones previously described by Ilizaliturri et al. The cartilage is then graded on a scale of 0 to 4 as follows: grade 0, normal articular cartilage lesions; grade 1, softening or wave sign; grade 2, cleavage lesion; grade 3, delamination; and grade 4, exposed bone. The site of the lesion is further classed as A, B or C based on whether the lesion is less than one-third of the distance from the acetabular rim to the cotyloid fossa, one-third to two-thirds of the same distance and greater than two-thirds of the distance, respectively. In order to validate the classification system, six surgeons graded ten video recordings of hip arthroscopy.

Our findings showed a high intra-observer reliability of the classification system with an intraclass correlation coefficient of 0.81 and a high interobserver reliability with an intraclass correlation coefficient of 0.88.

We have developed a simple reproducible classification system for lesions of the acetabular cartilage, which it is hoped will allow standardised documentation to be made of damage to the articular cartilage, particularly that associated with femoroacetabular impingement.

The April 2012 Children’s orthopaedics Roundup³⁶⁰ looks at osteonecrosis of the femoral head and surgery for dysplasia, femoral head blood flow during surgery, femoroacetabular impingement and sport in adolescence, the Drehmann sign, a predictive algorithm for septic arthritis, ACL reconstruction and arthrofibrosis in children, spinal cord monitoring for those less than four years old, arthroereisis for the flexible flat foot, fixing the displaced lateral humeral fracture, and mobile phones and inclinometer applications

We retrospectively analysed the MR scans of 25 patients with patellofemoral dysplasia and ten control subjects, to assess whether there was any change in the morphology of the patella along its vertical length. Ratios were calculated comparing the size of the cartilaginous and subchondral osseous surfaces of the lateral and medial facets. We also classified the morphology using the scoring systems of Baumgartl and Wiberg. There were 18 females and seven males with a mean age of 20.2 years (10 to 29) with dysplasia and two females and eight males with a mean age of 20.4 years (10 to 29) in the control group.

In the patient group there was a significant difference in morphology from proximal to distal for the cartilaginous (Analysis of variance (ANOVA) p = 0.004) and subchondral osseous surfaces (ANOVA, p = 0.002). In the control group there was no significant difference for either the cartilaginous (ANOVA, p = 0.391) or the subchondral osseous surface (ANOVA, p = 0.526).

Our study has shown that in the dysplastic patellofemoral articulation the medial facet of the patella becomes smaller in relation to the lateral facet from proximal to distal. MRI is needed to define clearly the cartilaginous and osseous morphology of the patella before surgery is considered for patients with patellofemoral dysplasia.

Objectives

Numerous complications following total knee replacement (TKR) relate to the patellofemoral (PF) joint, including pain and patellar maltracking, yet the options for in vivo imaging of the PF joint are limited, especially after TKR. We propose a novel sequential biplane radiological method that permits accurate tracking of the PF and tibiofemoral (TF) joints throughout the range of movement under weightbearing, and test it in knees pre- and post-arthroplasty.

The treatment of chronic osteomyelitis often includes surgical debridement and filling the resultant void with antibiotic-loaded polymethylmethacrylate cement, bone grafts or bone substitutes. Recently, the use of bioactive glass to treat bone defects in infections has been reported in a limited series of patients. However, no direct comparison between this biomaterial and antibiotic-loaded bone substitute has been performed.

In this retrospective study, we compared the safety and efficacy of surgical debridement and local application of the bioactive glass S53P4 in a series of 27 patients affected by chronic osteomyelitis of the long bones (Group A) with two other series, treated respectively with an antibiotic-loaded hydroxyapatite and calcium sulphate compound (Group B; n = 27) or a mixture of tricalcium phosphate and an antibiotic-loaded demineralised bone matrix (Group C; n = 22). Systemic antibiotics were also used in all groups.

After comparable periods of follow-up, the control of infection was similar in the three groups. In particular, 25 out of 27 (92.6%) patients of Group A, 24 out of 27 (88.9%) in Group B and 19 out of 22 (86.3%) in Group C showed no infection recurrence at means of 21.8 (12 to 36), 22.1 (12 to 36) and 21.5 (12 to 36) months follow-up, respectively, while Group A showed a reduced wound complication rate.

Our results show that patients treated with a bioactive glass without local antibiotics achieved similar eradication of infection and less drainage than those treated with two different antibiotic-loaded calcium-based bone substitutes.

Cite this article: Bone Joint J 2014; 96-B:845–50.

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