This large UK multicentre study evaluates clinical outcomes and identifies factors associated with local complication following PFR for non-oncological conditions.

132 patients across four UK centres underwent PFR from 01/08/2004-28/03/2023 with median follow-up of 1.9 (Q10.5-Q34.2) years. 75 (56.8%) patients were female and the mean age was 74.0 (SD 11.7) years. 103 (78%) patients had Charleston Comorbidity Index ≥3. ASA class was III or IV in 66.6%. Indications were infected revision (39, 29.5%), periprosthetic fracture (36, 27.3%), acute trauma (30, 22.7%), aseptic revision (17, 12.9%), failed trauma (nine, 6.8%) and complex primary arthroplasty (one, 0.8%). The primary outcome was the local complication rate. Secondary outcomes were systemic complications, reoperation and mortality rates. Comparisons were made with t-tests and Chi2 tests to investigate patient and surgical factors associated with local complication. Statistical significance was p<0.05.

There were 37(28.0%) local complications. These were 18 (13.6%) dislocations, eight (6.1%) prosthetic joint infections, four (3.0%) haematomas, three (2.3%) superficial infections, one (0.8%) wound dehiscence, one (0.8%) sciatic nerve palsy and one (0.8%) femoral perforation. Dislocation mostly occurred in conventional articulations (12, 9.1%) followed by dual-mobility cups (three, 2.3%), constrained cups (two, 1.5%) and hemiarthroplasty (one, 0.8%). Median time to local complication was 30 (Q14-Q3 133) days. Seven (5.3%) patients developed a systemic complication. Thirty-three (25.0%) patients underwent reoperation. Thirty-day and one-year mortality rates were 3.8% and 12.1%, respectively. Longer surgical waiting times (7.9 \[SD 16.9) versus 2.6 \[SD 4.4\] days, p<0.001) and longer operating times (212.5 \[SD 71.8\] versus 189.4 \[SD 59.3\] mins, p=0.0450) were associated with local complication.

Due to its high complication rate, PFR should be a salvage option when performed for non-oncological indications. Conventional articulations should be avoided. PFR should be delivered in a timely manner and ideally as dual-consultant cases to reduce operating time.

Periprosthetic femoral fracture (PFF) incidence following hip replacement surgery continues to rise. There is a national drive to centralise PFF treatment within specialist centres to improve clinical outcomes and cost-effectiveness. The financial implications of treating PFFs must be analysed to guide allocation of funding.

Data were collected for 129 PFFs admitted from 02/04/2014–19/05/2020. Financial data were provided by the Patient Level Information and Costing Systems (PLICS) team. Primary outcomes were cost, revenue and margin for each PFF. Additional data were collected on length of stay (LOS), critical care requirements and clinical outcomes. Statistical comparisons were made between treatment type (fixation vs revision). Significance was set to p<0.05.

Across the entire cohort, total cost was £2,389,901, total revenue was £1,695,435 and total loss was £694,481. Highest costs were ward stay (£714,591), theatre utilisation (£382,625), and overheads (£249,110). Median cost was £15,863 (IQR, £11,092-£22,221), median revenue was £11,305 (IQR, £7,147-£15,222) and median loss was £3,795 (IQR, £605-£8687). Median LOS was 21 days (IQR 13–34) and 28.7% patients required critical care admission.

Ninety-six patients were treated operatively with either fixation (n=53) or revision (n=43). Median operating time was lower for fixation versus revision (132 [IQR, 115–185] vs 201 [IQR, 159–229] minutes, p=0.001). Median cost (£17,455 [IQR, £13,095-£22,824] vs £17,399 [£13,394-£23,404]) and median loss (£5,774 [IQR, £2,092-£10,472] vs £3,860 [IQR, £96-£7,601]) were similar for fixation and revision (p=0.99 and p=0.18, respectively). Median revenue was greater for revision versus fixation (£13,925 [IQR, £11,294-£17,037] vs £12,160 [IQR, £8,486-£14,390], p=0.02). There was no difference in LOS (21 [13–34] vs 21 [14–30] days, p=0.94), critical care requirements (20 [37.7%] vs 11 [25.6%], p=0.30), reoperations (3 [5.7%] vs 6 [14.0%], p=0.29], local complications (8 [15.1%) vs 12 [27.9%], p=0.20) or systemic complications (11 [20.8%] vs 11 [25.6%], p=0.75) between fixation and revision.

PFF treatment costs are high with inadequate reimbursement through tariff. Work is needed to address this disparity and reduce costs associated with LOS, theatre utilisation and implants. Treatment cost should not be used when deciding between fixation and revision surgery.

Cemented total hip replacement (THR) provides excellent outcomes and is cost-effective. Polished taper-slip (PTS) stems demonstrate successful results and have overtaken traditional composite-beam (CB) stems. Recent reports indicate they are associated with a higher risk of postoperative periprosthetic femoral fracture (PFF) compared to CB stems. This study evaluates risk factors influencing fracture characteristics around PTS and CB cemented stems.

Data were collected for 584 PFF patients admitted to eight UK centres from 25/05/2006-01/03/2020. Radiographs were assessed for Unified Classification System (UCS) grade and Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) type. Statistical comparisons investigated relationships by age, gender, and stem fixation philosophy (PTS versus CB). The effect of multiple variables was estimated using multinomial logistic regression to estimate odds ratios (OR) with 95% confidence intervals (CI).

Median (IQR) age was 79.1 (72.0–86.0) years, 312 (53.6%) patients were female, and 495 (85.1%) stems were PTS. The commonest UCS grade was type B1 (278, 47.6%). The commonest AO/OTA type was spiral (352, 60.3%). Metaphyseal-split fractures occurred only with PTS stems with an incidence of 10.1%. Male gender was associated with a five-fold reduction in odds of a type C fracture (OR 0.22, 95% CI 0.12 to 0.41, p<0.001) compared to a type B fracture. CB stems were associated with significantly increased odds of transverse fracture (OR 9.51, 95% CI 3.72 to 24.34, p <0.001) and wedge fracture (OR 3.72, 95% CI 1.16 to 11.95, p <0.05) compared to PTS stems.

This is the largest study investigating PFF characteristics around cemented stems. The commonest fracture types are B1 and spiral fractures. PTS stems are exclusively associated with metaphyseal-split fractures, but their incidence is low. Males have lower odds of UCS grade C fractures compared to females. CB stems had higher odds of bending type fractures (transverse and wedge) compared to PTS stems. Biomechanical testing is needed for validation and investigation of modifiable factors which may reduce the risk of unstable fracture patterns requiring complex revision surgery over internal fixation.

Aims

This study evaluates risk factors influencing fracture characteristics for postoperative periprosthetic femoral fractures (PFFs) around cemented stems in total hip arthroplasty.

Introduction

Reverse hybrid total hip replacement (THR) offers significant theoretical benefits but is uncommonly used. Our primary objective was to evaluate implant survival with all cause revision and revision for aseptic loosening of either component as endpoints.

Introduction

The MHRA guidelines for metal on metal (MOM) suggest cobalt and chromium levels of more than 7ppb as potential for soft tissue reaction. However, in some patients soft tissue reaction is seen even in the presence of normal serum metal ions levels.

Background

Revision surgery for a failed metal on metal (MoM) hip arthroplasty is often unpredictable and challenging due to associated massive soft tissue and bony lesions. We present the analysis and early outcomes of revision surgery in failed MoM hip arthroplasties at our institution.

A prospective study was done to assess the outcome of MPFL reconstruction for patellar instability using quadriceps graft. MPFL reconstruction was done using superficial strip of quadriceps by an anteromedial incision and attached close to medial epicondyle of femur. There were 15 knees in thirteen patients with a mean age of 23.4 years. All patients had MPFL reconstruction and 5 had tibial tuberosity transfers. With a mean follow-up of 39.4 (12–57) months, the mean pre-op Kujala scores improved from 47.8 to 87.2. The mean Lysholm scores improved from 54.2 to 86.8. None of the patients had patella re-dislocations. MPFL reconstruction with quadriceps graft appears to be effective producing good results in patients with patellar instability.

To analyse the intra-operative variation in mechanical axes of the lower limb at various stages during navigated total knee replacement.

A prospective study was performed to analyse the intra-operative variation in the mechanical axes of the lower limb during navigated total knee replacement. All consecutive patients who underwent navigated total knee replacement were included and patients with inadequate data were excluded from the study. The intra-operative initial, trial and the final mechanical hip-knee-ankle axes were recorded from the navigation system. The differences between these axes were calculated and analysed. There were forty patients, of which 24 were females and 16 males with the age ranging from 37-89 (average 68.4) years. The right knee was replaced in 27 and the left knee in 13 patients. The average initial mechanical axes alignment was 0.03° valgus (3° varus to 3° valgus), trial alignment 0.64° varus (3° varus to 1.5° valgus) and final alignment 0.25° varus (4° varus to 4° valgus). Average deviation from initial to trial axes was 0.97°, trial to final axes was 0.74° and initial to final axes was 1.08°. The correlation co-efficient between the initial and the trial axes was 0.25, trial and final axes was 0.43 & initial and final axes was 0.09.

This study highlights a significant variation in mechanical axes between the different stages of navigated total knee replacement. The potential sources of intra-operative errors causing these changes could be soft tissue imbalance, variations in implant placement and possible tracker micro motion. Execution of bony cuts in near normal neutral alignment does not guarantee achievement of near normal final alignment. We advocate surgeons to be vigilant to avoid potential malalignment during navigated total knee replacement.

Background

A retrospective review of all patients transferred by helicopter ambulance to the Great Western Hospital over a 20-month period between January 2003 and September 2004 was undertaken to establish the case-mix of patients (trauma and non-trauma) transferred and the outcome of their admission and length of hospital stay.

Introduction: Glenohumeral arthritis secondary to chronic cuff deficiency not only leads to serious compromise in shoulder function but also poses a surgical challenge. There is no consensus regarding management of this problem although different arthroplasty options have been tried with variable results. We present our experience with managing this difficult problem using a shoulder resurfacing and subscapularis Z-plasty in order to improve shoulder movements, pain and function.

Patient and Methods: This study was conducted on 30-patients with rotator cuff arthropathy operated by a single surgeon at a district general hospital. There were 21 female and 9 male patients with mean age 73 years (range 62–85 years). The average duration of symptoms prior to treatment was 5.45 years (range 2–15 years). Twenty patients had uncemented shoulder resurfacing while remaining ten patients had cemented resurfacing procedure. The mean follow-up was 21 months (range 36–18 months). The patients were assessed at 3 months, 6 months, 12 months and 24 months postoperatively with European Society for shoulder and Elbow Surgery Score (ESSES) and radiograph at each visit.

Results: The ESSES score significantly improved from a mean of 47.5 preoperatively to 77.5 postoperatively, with most improvement being in subjective scoring (pain and ADL) followed by improvement in external rotation and forward flexion movement due to lengthening of subscapularis by Z-plasty. The VAS score for pain improved from average 7.4 preoperatively to 0.9 at 6 months postoperatively. On subjective scoring most patients reported good to excellent result at 6 months following surgery. There was no difference in outcome scores between cemented and uncemented resurfacing groups. No intraoperative or postoperative complications were encountered.

Our early results with shoulder resurfacing in management of rotator cuff arthropathy are encouraging. This bone conserving surgery may serve as an alternative to major procedures like reverse shoulder arthroplasty in selected group of patients.

Introduction: Clavicle fractures represent 5% of fractures in adults and almost 44% of shoulder injuries and are usually treated none operatively with good results. However significantly displaced fractures can be associated with high non-union rate and there is a lack of consensus on when surgical treatment is indicated for such fractures. The aim of this study was to identify guidelines for surgical intervention, safer surgical approach and outcome of surgical intervention.

Method: A retrospective audit of all clavicle fractures managed surgically over past 5 years (March 2004 to 2009) in a district general hospital. Case notes were reviewed to study the surgical indication, surgical approach, patient satisfaction and oxford should score and need for metal work removal.

In all 35 patients (29 male) underwent surgery for significant fracture displacement with shortening, manual workers and keen sportsmen at the time of injury. The infraclavicular approach was used in 21 patients and 14 patients had direct incision approach. Radiological union was achieved in all patients after an average of 13.26(8–24) weeks. Six patients required plate removal at 6 months following surgery, infraclavicular (2 patients) & direct approach (4 patients). All patients returned to their original occupation at average 2.55 months. The Oxford Shoulder Score at 3 months after surgery was average 15 (range12–20) and all patients, except one, scored excellent on subjective scoring.

Conclusion: Our study showed excellent surgical outcome for displaced clavicle fractures in young and active patients and is supported by the high union rate, good oxford shoulder score, early return to work and high patient satisfaction scores. The infraclaviculr approach is a betterthan direct approach based on the low complication rate and less need for metal work removal.

Purpose: To evaluate retrospectively the functional and radiographic outcome of patients who had a thumb trapeziometacarpal (TM) joint arthrodesis using a T-plate, chevron bone cuts and autologous punch graft harvested from ipsilateral distal radius.

Material and Methods: Between 2001 and 2006, 32 trapeziometacarpal (TM) joint fusions were performed in 24 patients using the above technique. The study group comprised of 16 females and 8 males with average age 52 years (range 42–62 years). Average follow-up was 14.8 months (range 14–60 months). Indications for surgery were: failure of conservative treatment; severe pain; and diminished thumb function hampering everyday life. All patients had radiological evidence of advanced TM joint arthritis (Eaton and Littler grade II to III).

In all cases, chevron bone cuts have been used. The fixation has progressed from K-wires, through single and double lag screws, tension-band wire, to an AO mini T-plate which is the present technique. With the K-wire, or simple screw methods, the failure rates were up to 50%, leading to many revision operations. Bone graft is used; in first 15 cases this was ‘Allomatrix’ but we now use local bone from the distal radius, taken with an AO tap guide used as a trephine.

Functional outcomes were assessed using Quick DASH score, and Gartland and Werley score. There was also a radiographic review. The grip and pinch strength were compared with the contralateral side. We also looked at the progression of disease at scaphotrapezial joint after the fusion of TM joint.

Results: Patient-rated outcome scores indicated very good pain relief with preservation of grip and pinch strength. There were 2 cases (7%) of non-union which required revision surgery and were probably due to poor screw placement in the trapezium. In 8 patients (25%), pain related to prominent metalwork required plate removal. In no case was there x-ray or symptomatic progression of the disease at scaphotrapezial joint. Clinically, 75% rated good, 15% fair, and 10% poor results.

Conclusion: The present form of trapeziometacarpal arthrodesis is reproducible and offers an excellent alternative to trapeziectomy especially in younger patients.

Type of study/level of evidence: Therapeutic IV.

Purpose: To evaluate retrospectively the functional and radiographic outcome of patients who had a thumb trapeziometacarpal (TM) joint arthrodesis using a T-plate, chevron bone cuts and autologous punch graft harvested from ipsilateral distal radius.

Material and Methods: Between 2001 and 2006, 32 trapeziometacarpal (TM) joint fusions were performed in 24 patients using the above technique. The study group comprised of 16 females and 8 males with average age 52 years (range 42–62 years). Average follow-up was 14.8 months (range 14–60 months). Indications for surgery were: failure of conservative treatment; severe pain; and diminished thumb function hampering everyday life. All patients had radiological evidence of advanced TM joint arthritis (Eaton and Littler grade II to III).

In all cases, chevron bone cuts have been used. The fixation has progressed from K-wires, through single and double lag screws, tension-band wire, to an AO mini T-plate which is the present technique. With the K-wire, or simple screw methods, the failure rates were up to 50%, leading to many revision operations. Bone graft is used; in first 15 cases this was ‘Allomatrix’ but we now use local bone from the distal radius, taken with an AO tap guide used as a trephine.

Functional outcomes were assessed using Quick DASH score, and Gartland and Werley score. There was also a radiographic review. The grip and pinch strength were compared with the contralateral side. We also looked at the progression of disease at scaphotrapezial joint after the fusion of TM joint.

Results: Patient-rated outcome scores indicated very good pain relief with preservation of grip and pinch strength. There were 2 cases (7%) of non-union which required revision surgery and were probably due to poor screw placement in the trapezium. In 8 patients (25%), pain related to prominent metalwork required plate removal. In no case was there x-ray or symptomatic progression of the disease at scaphotrapezial joint. Clinically, 75% rated good, 15% fair, and 10% poor results.

Conclusion: The present form of trapeziometacarpal arthrodesis is reproducible and offers an excellent alternative to trapeziectomy especially in younger patients.

Type of study/level of evidence: Therapeutic IV.

Introduction:: Various reference axes are used in total knee arthroplasty to determine the femoral rotation including transepicondylar axis, posterior condylar axis and Whiteside’s line. However, there are currently no golden standards as to the ideal axes to determine the true femoral rotation.

Materials and Methods: A prospective observational study was performed to analyse the various axes used to determine femoral rotation during total knee replacement. All consecutive patients who underwent MRI of the knee between December 2006 and May 2007 were considered to be included in the study. Patients below the age of 20 years, above the age of 40 years and mass lesions obscuring the bony landmarks were excluded. The transepicondylar, posterior condylar, posterior femoral cortical, anterior femoral cortical and tibial anteroposterior axes were measured on the PACS system.

Results: Of the 100 patients, there were 75 males and 25 females with a mean age of 31(20–39) years. The mean relation between the posterior condylar axes and transepicondylar axes was 3.9 (SD−1.71, 95% CI 3.58–4.26), posterior condylar axes and posterior femoral cortical axes was 5.85 (SD−2.76, CI 5.3–6.4), posterior condylar axis and anterior cortical axis was 6.21 (SD−3.09, CI 5.6–6.8) and posterior condylar axes and tibial anteroposterior axes was 89.6 (SD−5.18, CI 88.5–90.6).

Conclusion: The transepicondylar axis appears to be the most consistent amongst the landmarks used to determine femoral rotation. However even the transepicondylar axis shows a significant variation. If transepicondylar axis is not available we suggest the use of femoral anterior cortical axes as a reference landmark

Background: Arthrodesis is still the recommended treatment for end-stage hallux rigidus in young and active patients. Silicone implant arthroplasty of great toe was first described back in 1979 by Swanson et. al. Over the years, total joint replacement arthroplasty has taken over, as the apparent complication rate with silicone appeared high.

Objective: The objective of this retrospective study was to analyse medium to long-term clinical outcomes and patient satisfaction of patients with silastic implant arthroplasty of great toe.

Methods: Between May 1996, and December 2004, 65 patients totalling 76 first metatarsophalangeal silastic implants were evaluated both subjectively and objectively. The group comprised of 25 males and 40 females with average age 56 years (26–86). The average time of follow-up was 6 years (2–11). 12 patients (18%) has previous metatarsal osteotomy with bunionectomy for hallux valgus.

Outcomes were assessed by overall subjective satisfaction, Visual Analogue Scale (VAS) for pain, functional scores, range of motion and radiographic evaluation.

Results: Overall success rate was over 80%. 90% patients reported good pain relief after the operation. All patients regained satisfactory range of movement in the joint. The average flexion was 110 (5–200) and extension 200 (10–300). None of the patients reported difficulty in walking or slow running.

6 patients (9%) complained of persisting mild to moderate pain and swelling in the joint. 2 patients (3%) were not happy with the level of deformity correction. All the above 8 patients declined to have joint arthrodesed. 2 patients (3%) had deep infection requiring implant removal. 1 patient had osteolysis on the x-rays but remain asymptomatic. Although radiographic deterioration of the implant was demonstrated in a lot of implants, this deterioration did not correlate with patient satisfaction.

We conclude that silastic first metatarsophalangeal joint replacement is a proven procedure that not only provides long- term pain relief but also satisfactory range of movement. Therefore it should still be considered as an option in patients with end-stage hallux rigidus.

To analyse the intra-operative variation in mechanical axes of the lower limb at various stages during navigated total knee replacement. A prospective study was performed to analyse the intra-operative variation in the mechanical axes of the lower limb during navigated total knee replacement. All consecutive patients who underwent navigated total knee replacement were included and patients with inadequate data were excluded from the study. The intra-operative initial, trial and the final mechanical hip-knee-ankle axes were recorded from the navigation system. The differences between these axes were calculated and analysed. There were forty patients, of which 24 were females and 16 males with the age ranging from 37–89 (average 68.4) years. The right knee was replaced in 27 and the left knee in 13 patients. The average initial mechanical axes alignment was 0.03° valgus (3° varus to 3° valgus), trial alignment 0.64° varus (3° varus to 1.5° valgus) and final alignment 0.25° varus (4° varus to 4° valgus). Average deviation from initial to trial axes was 0.97°, trial to final axes was 0.74° and initial to final axes was 1.08°. The cor-relation co-efficient between the initial and the trial axes was 0.25, trial and final axes was 0.43 & initial and final axes was 0.09.

This study highlights a significant variation in mechanical axes between the different stages of navigated total knee replacement. The potential sources of intra-operative errors causing these changes could be soft tissue imbalance, variations in implant placement and possible tracker micro motion. Execution of bony cuts in near normal neutral alignment does not guarantee achievement of near normal final alignment. We advocate surgeons to be vigilant to avoid potential malalignment during navigated total knee replacement.

AIM: The purpose of this retrospective study was to assess the results of a novel surgical technique for chronic lateral ankle instability using dynamic extensor digitorum brevis (EDB) muscle transfer.

METHODS: 15 patients underwent dynamic EDB muscle transfer for symptomatic chronic lateral ankle instability. All patients were quite fit and physically very active. 9 male and 6 female patients, mean age 27 (range, 22–32) were operated by single surgeon (ALP) between March 2003 and August 2005. All patients had standard procedure involving proximal transfer of the origin of EDB muscle whilst preserving its neuro-vascular pedicle. All patients went through a standard post-operative physiotherapy protocol including pro-prioceptive training. Mean follow-up was 24 months (range, 12–36 months). The mean functional Karlsson scores improved from 26.5 before surgery to 86.5 at 12 months after surgery. At follow-up, all patients had normal range of ankle movements and were functionally stable. All patients regained their pre-injury activity level at 12 months after surgery. There were no early or late complications in our series.

DISCUSSION: Ankle sprains are the most common injuries sustained during sports and physical exercise. Treatment is usually conservative because most of these injuries heal without consequence. However, symptomatic chronic lateral ankle instability is a difficult problem to treat and several surgical techniques have been described. EDB muscle not only acts as a dynamic substitute for the deficient ligament but also overcomes the problem of over-tightening of the ligament leading to restricted supination.

CONCLUSION: Dynamic EDB muscle transfer is a safe, clinically effective and reliable surgical option for symptomatic chronic lateral ankle instability.

Significant concerns remain in computer navigated surgery regarding potential errors due to inadequate tracker or array fixation, cutting guide block movements, saw blade deviation, variable component seating and standardisation and validity of radiographic measurements of alignment for outcome assessment. There are no studies in the literature comparing computer generated axes at different steps of operation as well as radiographic axes using scanograms to our knowledge. Long leg films involve significant radiation, which can be minimised by the use of scanograms.

A prospective study was performed to compare the per-operative and post-operative alignment of the lower limbs after navigated total knee replacements. All consecutive patients who underwent navigated total knee replacement between May 2006 and November 2006 were included in the study. Patients with inadequate data, patients who refused to participate in the study or lost contact, obvious measurement errors and patients having had recent operations were excluded. The intra-operative initial, trial and the final axes were recorded from the navigation system. Post-operatively a CT (Computer Tomogram) scanogram of the lower limbs was performed as per the scanogram protocol. Measurement of the mechanical hip-knee-ankle axis of the lower limb was performed on the computer. Results were analysed using appropriate statistical methods and comparison made between initial, trial, final and scanogram axes with assessment of their correlation coefficients.

Twenty-five patients were initially recruited in the study, of which, 15 were available with completed data. There were four males and 11 females with the age ranging from 57–80 (average 70) years. The right knee was replaced in 12 and the left knee in three patients. The average initial alignment was 0.09° valgus (0.5° varus to 1° valgus), trial alignment 0.59° varus (2° varus to 1° valgus), final alignment 0.56° varus (4° varus to 1.5° valgus) and average radiographic alignment was 0.52° varus (3.1° varus to 1.8° valgus) in maximum possible extension. Average deviation from initial to trial alignment was 0.69° varus, trial to final was 0.03° varus and final to radiographic alignment was 0.12° valgus.

Correlation co-efficient of 0.62 between the initial and final axes with average difference of 0.72° varus (p= 0.11, unequal variance 2 tailed) demonstrates reasonable reproducibility of the alignment with computer-guided surgery, also confirming the fact that there is some variation between the initial cut angles and final mechanical axes. Correlation co-efficient of 0.92 between final axes and radiographic axes suggests that scanogram is an imaging modality with reasonable accuracy for measuring mechanical limb alignment despite significantly low radiation and relatively low resolution. Potential errors in radiographic measurements due to rotational malposition combined with flexion deformity is highlighted.

This study aimed to A) establish a protocol for measuring periprosthetic bone mineral density (BMD) of the proximal humerus following implant arthroplasty, and B) compare the differences in the periprosthetic BMD values 4–9 years after surface replacement and stemmed arthroplasties of the proximal humerus. The study design was of retrospective independent samples cohorts, of patients who had received a proximal humeral arthroplasty between January 1992 and December 1996 in a tertiary referral shoulder unit of a UK hospital. The exclusion criteria were A) patient unavailable for study, B) patient refusal, C) inadequate information of dependent and independent variables, or D) obvious measurement errors.

All available patients underwent DEXA scanning of the proximal humerus using a Lunar DPXL scanner fitted with Orthopaedic Hip software version 1.3. Replicable patient positioning with a special jig was used. On a predetermined format of Gruen equivalent zones and sub-zones, BMD values in gm/cm² were plotted. Cortical thickness on plain radiographs was recorded for each zone. Femoral neck DEXA scan was performed to obtain a proportionate value of BMD of the proximal humerus, in order to eliminate the effect of confounding variables. Confounding variables accounted for were age, gender, height, weight, activity level, indication for surgery, duration of implantation, dominance, type of arthroplasty (hemi or total) and use of cemented or uncemented stemmed implants. Statistical analysis was performed using Microsoft excel as well as SPSS software.

Initially, 58 shoulders in 52 patients were recruited. 6 patients declined to participate for ill health, 6 had moved out of the area and 8 did not attend or reply. Of the remaining 31 shoulders in 25 patients, 2 patients had an obviously erroneous DEXA reading. 29 shoulders in 23 patients were finally analysed, which included 10 male and 19 female shoulders. Average age was 67.5 years and average time since surgery was 6 years 2 months. Indications for surgery were RA in 14, OA in 8 and other reasons in 7. Of 29 shoulders, 20 received a total replacement, 9 a hemiarthroplasty.

The inevitable obliquity of the image caused some difficulties in maintaining accuracy and difficulties were observed due to limitation of the software to measure thin cortices and to distinguish between the cement and bone. There was no significant correlation between gross cortical thickness and BMD values, and the average periprosthetic BMD was 0.54 g/cm². Surface replacement implants were associated with relative preservation of proximal medial cortex and higher BMD values in this region. BMD values were consistently higher at the level of stem tip for the stemmed implants. No such phenomenon was observed for the surface replacement prostheses. Hemiarthroplasty was associated with relatively higher BMD values in the proximal medial cortical region than total arthroplasty.