Aims

Previous research has demonstrated increased early complication rates following total hip arthroplasty (THA) in obese patients, as defined by body mass index (BMI). Subcutaneous fat depth (FD) has been shown to be an independent risk factor for wound infection in cervical and lumbar spine surgery, as well as after abdominal laparotomy. The aim of this study was to investigate whether increased peritrochanteric FD was associated with an increased risk of complications in the first year following THA.

Aims

The aim of this retrospective audit was to determine the route of referral or presentation of patients requiring revision following primary total hip arthroplasty (THA).

Aims

Our aim was to report survivorship data and lessons learned with the Corail/Pinnacle cementless total hip arthroplasty (THA) system.

Ideal placement of the acetabular component remains elusive both in terms of defining and achieving a target. Our aim is to help restore original anatomy by using the transverse acetabular ligament (TAL) to control the height, depth and version of the component. In the normal hip the TAL and labrum extend beyond the equator of the femoral head and therefore, if the definitive acetabular component is positioned such that it is cradled by and just deep to the plane of the TAL and labrum and is no more than 4mm larger than the original femoral head, the centre of the hip should be restored. If the face of the component is positioned parallel to the TAL and psoas groove the patient specific version should be restored. We still use the TAL for controlling version in the dysplastic hip because we believe that the TAL and labrum compensate for any underlying bony abnormality.

The TAL should not be used as an aid to inclination. Worldwide, > 75% of surgeons operate with the patient in the lateral decubitus position and we have shown that errors in post-operative radiographic inclination (RI) of > 50° are generally caused by errors in patient positioning. Consequently, great care needs to be taken when positioning the patient. We also recommend 35° of apparent operative inclination (AOI) during surgery, as opposed to the traditional 45°.

Cite this article: Bone Joint J 2016;98-B(1 Suppl A):37–43.

Ceramic-on-metal (CoM) is a relatively new bearing combination for total hip arthroplasty (THA) with few reported outcomes. A total of 287 CoM THAs were carried out in 271 patients (mean age 55.6 years (20 to 77), 150 THAs in female patients, 137 in male) under the care of a single surgeon between October 2007 and October 2009. With the issues surrounding metal-on-metal bearings the decision was taken to review these patients between March and November 2011, at a mean follow-up of 34 months (23 to 45) and to record pain, outcome scores, radiological analysis and blood ion levels. The mean Oxford Hip Score was 19.2 (12 to 53), 254 patients with 268 hips (95%) had mild/very mild/no pain, the mean angle of inclination of the acetabular component was 44.8^o (28^o to 63^o), 82 stems (29%) had evidence of radiolucent lines of > 1 mm in at least one Gruen zone and the median levels of cobalt and chromium ions in the blood were 0.83 μg/L (0.24 μg/L to 27.56 μg/L) and 0.78 μg/L (0.21 μg/L to 8.84 μg/L), respectively. The five-year survival rate is 96.9% (95% confidence interval 94.7% to 99%).

Due to the presence of radiolucent lines and the higher than expected levels of metal ions in the blood, we would not recommend the use of CoM THA without further long-term follow-up. We plan to monitor all these patients regularly.

Cite this article: Bone Joint J 2015;97-B:300–5.

In an initial randomised controlled trial (RCT) we segregated 180 patients to one of two knee positions following total knee replacement (TKR): six hours of knee flexion using either a jig or knee extension. Outcome measures included post-operative blood loss, fall in haemoglobin, blood transfusion requirements, knee range of movement, limb swelling and functional scores. A second RCT consisted of 420 TKR patients randomised to one of three post-operative knee positions: flexion for three or six hours post-operatively, or knee extension.

Positioning of the knee in flexion for six hours immediately after surgery significantly reduced blood loss (p = 0.002). There were no significant differences in post-operative range of movement, swelling, pain or outcome scores between the various knee positions in either study. Post-operative knee flexion may offer a simple and cost-effective way to reduce blood loss and transfusion requirements following TKR.

We also report a cautionary note regarding the potential risks of prolonged knee flexion for more than six hours observed during clinical practice in the intervening period between the two trials, with 14 of 289 patients (4.7%) reporting lower limb sensory neuropathy at their three-month review.

Cite this article: Bone Joint J 2014;96-B:201–9.

With greater numbers of younger patients undergoing total hip replacement (THR), the effect of patient age on the diameter of the femoral canal may become more relevant. This study aimed to investigate the relationship between the diameter of the diaphysis of the femoral canal with increasing age in a large number of patients who underwent THR. A total of 1685 patients scheduled for THR had their femoral dimensions recorded from calibrated radiographs. There were 736 males and 949 females with mean ages of 67.1 years (34 to 92) and 70.2 years (29 to 92), respectively. The mean diameter of the femoral canal was 13.3 mm (8.0 to 23.0) for males and 12.7 mm (6.0 to 26.0) for females. There was a poor correlation between age and the diameter of the canal in males (r = 0.071, p = 0.05) but a stronger correlation in females (r = 0.31, p < 0.001).

The diameter of the femoral canal diameter of a female patient undergoing THR could be predicted to increase by 3.2 mm between the ages of 40 and 80 years, in contrast a male would be expected to experience only a 0.6 mm increase during the same period. This increase in the diameter of the canal with age might affect the long-term survival of the femoral component in female patients.

Cite this article: Bone Joint J 2013;95-B:339–42.

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.

Restoration of leg length and offset is an important goal in total hip replacement. This paper reports a calliper-based technique to help achieve these goals by restoring the location of the centre of the femoral head. This was validated first by using a co-ordinate measuring machine to see how closely the calliper technique could record and restore the centre of the femoral head when simulating hip replacement on Sawbone femur, and secondly by using CT in patients undergoing hip replacement.

Results from the co-ordinate measuring machine showed that the centre of the femoral head was predicted by the calliper to within 4.3 mm for offset (mean 1.6 (95% confidence interval (CI) 0.4 to 2.8)) and 2.4 mm for vertical height (mean -0.6 (95% CI -1.4 to 0.2)). The CT scans showed that offset and vertical height were restored to within 8 mm (mean -1 (95% CI -2.1 to 0.6)) and -14 mm (mean 4 (95% CI 1.8 to 4.3)), respectively.

Accurate assessment and restoration of the centre of the femoral head is feasible with a calliper. It is quick, inexpensive, simple to use and can be applied to any design of femoral component.

The angle of inclination of the acetabular component in total hip replacement is a recognised contributing factor in dislocation and early wear. During non-navigated surgery, insertion of the acetabular component has traditionally been performed at an angle of 45° relative to the sagittal plane as judged by the surgeon’s eye, the operative inclination. Typically, the method used to assess inclination is the measurement made on the postoperative anteroposterior radiograph, the radiological inclination.

The aim of this study was to measure the intra-operative angle of inclination of the acetabular component on 60 consecutive patients in the lateral decubitus position when using a posterior approach during total hip replacement. This was achieved by taking intra-operative photographs of the acetabular inserter, representing the acetabular axis, and a horizontal reference. The results were compared with the post-operative radiological inclination.

The mean post-operative radiological inclination was 13° greater than the photographed operative inclination, which was unexpectedly high. It appears that in the lateral decubitus position with a posterior approach, the uppermost hemipelvis adducts, thus reducing the apparent operative inclination. Surgeons using the posterior approach in lateral decubitus need to aim for a lower operative inclination than when operating with the patient supine in order to achieve an acceptable radiological inclination.

We studied 4253 patients undergoing primary joint replacement between November 2002 and November 2007, of whom 4060 received aspirin only as chemical prophylaxis; 46 were mistakenly given low molecular weight heparin initially, which was stopped and changed to aspirin; 136 received no chemoprophylaxis and 11 patients received warfarin because of a previous history of pulmonary embolism. We identified the rate of clinical thromboembolism before and after discharge, and the mortality from pulmonary embolism at 90 days. The overall death rate was 0.31% (13 of 4253) and the rate of fatal pulmonary embolism was 0.07% (3 of 4253).

Our data suggest that fatal pulmonary embolism is not common following elective primary joint replacement, and with modern surgical practice elective hip and knee replacement should no longer be considered high-risk procedures.

Introduction: Blood loss is a major concern following total knee arthroplasty (TKA) frequently resulting in blood transfusions postoperatively. Various strategies exist to reduce blood loss and allogenic transfusion requirements. This study investigates the effect of immediate postoperative flexion on blood loss and transfusion requirements following TKA.

Methods: 180 consented patients undergoing primary TKA by a single surgeon were enrolled into a prospective randomised controlled study. 90 patients were randomised to have the operated knee nursed in extension postoperatively, and 90 patients to have the knee nursed in flexion for six hours postoperatively. Both groups followed a strict transfusion protocol. Data collected included calculated pre- and postoperative haemoglobin and haematocrit which was used to calculate total blood loss. Units transfused and postoperative complication rates were also recorded.

Results: There was no significant difference in demographics or factors predisposing to bleeding between the groups. The mean total blood loss was 1841mls for those in the extension group compared with 1587mls in the flexion group (p=0.02). The mean number of units transfused in the extension group was 0.78 units/patient compared with 0.36 units/patient in the flexion group (p=0.004). There was no significant difference in pain scores between the groups (p= 0.62).

Conclusion: This study shows that the use of immediate postoperative flexion significantly reduces calculated total blood loss and transfusion rates following TKA.

We have studied the concept of posterior condylar offset and the importance of its restoration on the maximum range of knee flexion after posterior-cruciate-ligament-retaining total knee replacement (TKR). We measured the difference in the posterior condylar offset before and one year after operation in 69 patients who had undergone a primary cruciate-sacrificing mobile bearing TKR by one surgeon using the same implant and a standardised operating technique. In all the patients true pre- and post-operative lateral radiographs had been taken.

The mean pre- and post-operative posterior condylar offset was 25.9 mm (21 to 35) and 26.9 mm (21 to 34), respectively. The mean difference in posterior condylar offset was + 1 mm (−6 to +5). The mean pre-operative knee flexion was 111° (62° to 146°) and at one year postoperatively, it was 107° (51° to 137°).

There was no statistical correlation between the change in knee flexion and the difference in the posterior condylar offset after TKR (Pearson correlation coefficient r = −0.06, p = 0.69).

We performed a randomised, controlled trial involving 150 patients with a pre-operative level of haemoglobin of 13.0 g/dl or less, to compare the effect of either topical fibrin spray or intravenous tranexamic acid on blood loss after total knee replacement.

A total of 50 patients in the topical fibrin spray group had 10 ml of the reconstituted product applied intra-operatively to the operation site. The 50 patients in the tranexamic acid group received 500 mg of tranexamic acid intravenously five minutes before deflation of the tourniquet and a repeat dose three hours later, and a control group of 50 patients received no pharmacological intervention.

There was a significant reduction in the total calculated blood loss for those in the topical fibrin spray group (p = 0.016) and tranexamic acid group (p = 0.041) compared with the control group, with mean losses of 1190 ml (708 to 2067), 1225 ml (580 to 2027), and 1415 ml (801 to 2319), respectively. The reduction in blood loss in the topical fibrin spray group was not significantly different from that achieved in the tranexamic acid group (p = 0.72).

Purpose: The objective of this study was to observe the change in transfusion rate by decreasing the transfusion trigger for patients undergoing primary total knee arthroplasty.

There are no transfusion guidelines defined for Total knee arthroplasty (TKA), and each orthopaedic unit usually has its own protocol when it comes to transfusion. With the present climate of concern about non-autologous blood transfusions and transmission of infection, orthopaedic units are trying to keep their transfusion rates to a minimum and only transfuse when absolutely necessary.

Method: The transfusion trigger prior to protocol change was a haematocrit (Hct) < 0.31, which was then changed to a lesser trigger of Hct < 0.25. We collected data on 331 patients; 181 patients prior to the change and 150 patients after the change. Each patient had undergone a primary TKA by a single surgeon using the same operative technique.

Results: In the group prior to change in transfusion trigger (Hct < 0.31), 76% of patients were transfused 88% of females and 54% of males. In this pre-trigger change group, 100% of patients with a pre-operative Hb of 12g/dl or less were transfused.

Of the 150 patients reviewed after the change in transfusion trigger (Hct < 0.25), only 29% were transfused – 35% of females and 18% of males. 50% of patients with a pre-operative Hb of 12 g/dl or less were transfused.

Conclusion: A change in the transfusion trigger greatly reduced the transfusion rate (reduction of 45%) with no adverse patient events. Obviously, this has both clinical and financial benefits. Pre-operative Hb is the best indicator as to whether a patient will require a transfusion following TKA. In order to decrease transfusion rates further, patients with a pre-operative Hb < 12 g/dl may benefit from pre-operative boosting of their Hb.

Purpose: The objective of this study was to observe the change in dislocation rate by introducing a capsular enhanced short external rotator repair during primary total hip arthroplasty.

Dislocation after primary total hip arthroplasty is a relatively common complication. The incidence is usually between 1% and 4%, although 0% to 10% has been reported in the literature. The posterior approach is by far the most popular by surgeons, but it reportedly has an increase risk of post-operative dislocation. The posterior approach causes disruption of the posterior capsule and the short external rotators. Studies have shown that repair of the posterior capsule and the short external rotators greatly reduce the dislocation rate.

Method: Review of the dislocation rate of THR’s by a single surgeon before and after the introduction of a capsular enhanced short external rotator repair (August 2002). It was a sequential cohort of 2213 Total Hip Replacements (THR), inserted over a period from January 1999 to June 2004. All cases were done by the senior author through a posterior approach using a Belfast custom stem, a 28mm head, and a cementless socket. We collected data on all dislocations which occurred on the hips inserted during this time period. We were therefore able to compare dislocation rates for THR’s done before and after the introduction of the soft tissue repair. The posterior capsule and short external rotators were reattached to the greater trochanter through drill holes using a number 5 Ethibond.

Results: This dislocation rate before the introduction of the new posterior soft tissue repair was 3.9% (58 out of 1501 THR’s). After the introduction of the repair the dislocation rate was 0.9% (6 out of 712 THR’s). 81% (47 of58) of dislocations before the change of practice were classed as early dislocations (with 3 months of surgery). 83% (5 of 6) were clearly dislocators after the new soft tissue repair. Considering only the early dislocations, the dislocation rate reduced from 3.1 to 0.7%.

Conclusion: Considering our reduction from 3.9% to0.9%, and results of previous studies, it is clear that the capsular enhanced and short external rotator repair is associated closely with a decreased dislocation rate. We feel other factors such as restoration of joint centre ensuring correct orientation of components are important in conjunction with the posterior soft tissue repair to keep dislocations to a minimum.

Purpose: The objective of this study was to assess whether a correlation existed between blood loss and soft tissue release carried out during total knee replacement in the valgus knee.

Method: We identified 208 patients with a valgus deformity undergoing primary total knee arthroplasty . These were performed over a 33 month period by a single surgeon. An LCS mobile bearing prosthesis was used in all patients. The valgus deformity range was from 1–38 degrees with a mean of 11.75 degrees. Haemoglobin (Hb) drop was calculated as a measure of blood loss. This was calculated using:

Hb drop = Pre-op Hb – (Day 3 Hb + No. of units of blood received)

(We assumed that one unit of blood equates to one gram increase in circulating haemoglobin).

Results: Osteoarthritis was the major diagnosis (90.3%) followed by rheumatoid disease (5.8%). Forty-four patients (21%) required no soft tissue release, this group having an average deformity of 6 degrees and an average Hb drop of 4.35g/dl. One hundred and forty-six (69%) patients required a posterolateral capsular release, average deformity of 14 degrees with an average Hb drop of 4.63g/dl. Seventeen (8%) patients had a posterolateral and an additional Iliotibial band release, average magnitude of deformity 18 degrees and average Hb drop of 4.97g/dl. One patient had a lateral collateral ligament release, magnitude of deformity 30 degrees and haemoglobin drop of 6.4g/dl.

Conclusion: Soft tissue release in total knee arthroplasties in the valgus knee increases the amount of postoperative bleeding and average length of stay of the patient.

Purpose: We describe our management of the valgus knee including release of tight lateral structures using a medial approach.

Method: Controversy surrounds which approach to use when undertaking a total knee replacement (TKR) in a fixed valgus knee. Poor patellar tracking is associated with this deformity and often rectified by a lateral retinacular release. Those favoring the lateral approach feel, although more demanding, it gives direct access to the tight lateral structures and avoids excessive devas-cularization to the patella, which may be associated with a lateral release and a medial arthrotomy.

Two hundred and eight consented patients (24.2%) were identified from 860 primary knee arthroplasties carried out over a 33-month period by a single surgeon. An LCS mobile bearing prosthesis was used in all cases. The mean valgus deformity measured 12.1 degrees (range 1–38). Fifty four percent of patients had a deformity of greater than 10 degrees. The patella was not resurfaced in any patient.

Results: Forty-four patients (21%) required no soft tissue release. The mean deformity was 6 degrees (range 2–13). Of the remaining 164 patients, 142 (87%) had a posterolateral capsule release, 17 (10%) posterolateral capsule and iliotibial band release, 4 (2.4%) posterolateral and direct posterior capsule release and 1 (0.6%) a lateral collateral ligament slide for fixed valgus deformity. The mean valgus deformity increased with each additional release required.

Of note 61 (29.3%) patients required a lateral patellar release for patellar maltracking. No patellar complications were noted. Mean patellar tilt was 1.1 degrees (sd=0.6 degrees) and mean patellar congruency 98% (sd=0.7%).

Conclusion: Using a medial approach in the valgus knee is technically less demanding than a lateral approach, can be used in any primary knee irrespective of the type of deformity and can restore patellar alignment without compromising viability at least in cases where the patella is not resurfaced.

Recent studies, including the Swedish Hip Register, have confirmed that modern cementing techniques are important to achieve long-term implant survival. Their ultimate goal is to obtain an increased strength of cement and its interfaces with bone, thereby maintaining secure fixation and effective load transmission.

The objective of this study was to measure the medullary pressures generated during bone cement injection, pressurisation and femoral prosthesis insertion for total hip arthroplasty. The measurements were recorded throughout the length of an in vitro femoral model while implanting a series of prosthetic hip stems using different pressurisation techniques. The prostheses used were the Charnley 40 flanged stem, an Exeter No. 3 stem, and a custom primary femoral component used in Belfast (Johnson & Johnson, DePuy International Ltd.). The following parameters were derived from the pressure data recorded; peak pressure, decay pressure and duration above 76 kPa, the pressure regarded as the threshold to obtain adequate bone penetration.

The range of peak distal stem pressures expected for all stems was 200–500kPa. The custom and Exeter stems generated proximal cement pressures in the range 100–300kPa. These pressures were attained through cement containment by stem design or auxiliary pressurising devices, respectively. It was observed that the Charnley femoral component did not perform as well with regard to proximal pressurisation, irrespective of which pressurisation technique was implemented. The durations of pressure maintenance above 76kPa are also important, 5 seconds being accepted as a minimum for an effective interface. These results reflect the pressure measurements, with adequate durations being maintained by those stems and pressurisers that were characterised by higher peak pressures.

It is concluded that stem design and the complementary cement management techniques are essential to realise the pressure/time characteristics that are regarded as necessary to form an optimum bone/cement interface.

Total knee arthroplasty has evolved considerably over the last thirty years. Early implant design achieved the short-term goals of pain relief and mobility, however loosening and polyethylene wear associated with over constraint was problematic. The Low Contact Stress total knee arthroplasty was developed in an attempt to address the problems of loosening and polyethylene wear. The highly congruent interface between the femoral component and the mobile insert minimises stress within the polyethylene and reduces the potential of wear and damage. Furthermore, the mobile bearing phenomenon minimises both torsional and shear stresses at the component bone interface. In our unit the impact of choice is the LCS rotating platform prosthesis, which is inserted with cruciate-sacrifice.

We reviewed 219 patients (272 knees) with an average follow-up of 6 years (5–8 years). In almost all cases the components were inserted with cement fixation. The patella was primarily resurfaced in 20 patients (21 knees). All operations were performed or supervised by the senior author. Female to male ratio was 2:1. Average age at surgery was 68 years (40–86) with osteoarthritis being the commonest primary diagnosis (89%). Postoperative range of motion ranges from 30–130° (average 103°). Average Oxford Knee, American Knee Society Score and Patellar Score was 19 (12–53), 160 (42–199) and 25 (4–30) respectively. Six patients (1.7%) required MUA at six weeks. Two patients (0.6%) required secondary patellar resurfacing. Three patients (0.8%) had revision of their components for persistent pain. At operation all components were noted to be well fixed. Spinout of the rotating platform occurred in one patient (0.3%). This was treated by exchange of the insert.

In conclusion, our early results of the LCS rotating platform prosthesis are encouraging with no cases of component loosening to date. This supports the continued use of the implant.

Currently, all details regarding implants are entered into a real time application on the Musgrave Park Hospital site using the Belfast Orthopaedic Information System (BOIS). This is a visual basic client application with data being stored in an SQL server database. This data collection system operates throughout every location within the hospital including the theatre block.

Loss of continuity occurs however when joint replacement takes place in Musgrave Park Hospital and then revision surgery or other procedures are carried out at other locations. The goal therefore of the Northern Ire-land Implant Register is to collect information on all implants performed and their revisions regardless of their location.

The dataset collected is based on the work of the National Joint Replacement Registry. Our system is designed to support and extend that dataset to provide a more comprehensive joint replacement registry database. This means that reports can be provided to individual sites and data entered into the National registry if required at a later stage.

At present every hospital in Northern Ireland is connected to the HPSS network (similar to the HPSSNet in the UK). What has been developed is a web browser based front end, which requires no complex software installation on any client machine. From this web based tool, staff at other locations can access information held at Musgrave Park Hospital, they can select an implant, or record a new implant and then link any revisions or other procedures carried out.

As all of the information is entered directly into the BOIS database, there is no delay in the information being available to all who access the system. This reduces the need for case notes to be transferred to other sites and the need to contact the other site directly regarding the case. The interface also provides a comprehensive reporting capability so that commonly requested standard reports are available for authorized staff to run from their web browser.

We present an overview of how the web interface works in practice and how data is entered into the system.

To maximise the long-term survivorship of any hip prosthesis it is important to recreate joint centre. Normal joint centre is determined by horizontal offset and vertical height of the acetabular and femoral components. In this study joint centre and horizontal offset were analysed in 200 consecutive patients operated on from October 1998 in whom the opposite hip was normal. Joint centre was defined relative to the acetabulum and femur both pre- and post-operatively. On the acetabular side a horizontal line was drawn across the pelvis immediately below each teardrop. A vertical line was drawn at right angles through the middle of each teardrop. Acetabular offset was defined as the horizontal distance from the vertical trans teardrop line to head centre. For femoral offset a screened x-ray was taken to show maximum offset. The anatomical axis was drawn and the offset was defined as the distance from the anatomical axis to head centre.

Our results show on the acetabular side there was an overall tendency to leave the joint centre medial and so decrease acetabular offset. However, we found that 90% of our sockets were placed within 6 mm of normal joint centre. We attribute this accuracy to the principle of visualising the transverse acetabular ligament intra-operatively and using this landmark to control depth of socket insertion. Conversely, on the femoral side there was a slight tendency to increase the offset. Nevertheless, 98% of the custom stems were within 10mm of normal joint centre. When we looked at total horizontal offset i.e. the combination of femoral and acetabular offset we found that joint centre had been restored to within 10mm in 93% of cases.

This study confirms the effectiveness of the custom femoral stem and Duraloc socket in restoring joint centre.

Rapidly progressive cases of primary idiopathic hip osteoarthrosis are well known and recognised. The prevalence reported in the literature varies from 4–18%. Three types have been identified- type 1 (rapid), type 2 (moderate) and type 3 (delayed) depending on the duration of chondrolysis and the subsequent rate of bone loss per year.

We reviewed the charts of all patients deemed to be RPO type 1 who had underwent hip arthroplasty under the care of the senior author (DEB) over a two-year period in an attempt to identify risk factors, which may have contributed to the rapid progression of their disease. All patients were treated using a custom femoral stem and a spiked Duraloc cementless socket following careful preparation of the acetabulum.

We identified 34 patients (40 hips) with type 1 rapidly progressive osteoarthrosis. Over the same time period 991 patients had underwent primary total hip arthroplasty, giving a prevalence of 4%. Of the 34 patients, 29 were female of average age 70.6 years (range, 51–83 years). All of the bilateral cases (6 patients) were female. Body mass index (BMI) for the female group ranged from 20.6 to 41.1Kg/m² (average, 28.2kg/m²) whilst that for the males was on average 25.8Kg/m² (range, 23.4–29.7Kg/m²).

Preoperative erythrocyte sedimentation rate (ESR) was 18mm/hr on average for the female group (range, 2–65mm/hr) and ranged from 3–52mm/hr (average, 20mm/hr) for the male patients. The preoperative Oxford Hip Score averaged 51 points for the female group and 48 points for the male group.

A detailed review of occupational history did not reveal any common occupational hazard. The majority of patients were non-smokers and denied any regular alcohol intake. Twenty-two patients (65%) had a history of hypertension. Twenty-seven patients (79%) had a history of non-steroidal anti-inflammatory use (most common preparation-diclofenac). Twenty-four patients (71%) resided in a rural area.

When compared to a cohort of patients undergoing primary total hip arthroplasty over the same time period, the only statistically significant risk factor identified was female gender.

We conclude, that patients who develop rapidly progressive osteoarthrosis of the hip are difficult to identify due to the absence of specific clinical features. We also outline our experience in the management of these technically challenging cases.

Many factors have been demonstrated to influence the range of knee movement that an individual can achieve.

The purpose of this study was to objectively demonstrate how range of knee movement is affected when the influence of pain is abolished.

Sixty-eight patients with degenerative joint disease presenting for primary total knee arthroplasty were recruited. Using a digital camera, images were taken before and after the induction of anaesthesia with the lower limb in four positions- extension, forced extension, flexion and forced flexion. Camera set up was standard and the range of knee motion was measured from the digital images.

Average arc of motion before anaesthesia was 96° (range, 41°–157°). After induction of anaesthesia, the arc of motion increased to 115° (range, 410–161°). Knee extension improved by an average of 5° (range, 0–15°) and flexion improved by an average of 16° (range, 0–65°).

In conclusion, these results demonstrate that pain has a significant inhibitory effect on the measured range of knee movement before surgical intervention.

Introduction: Since 1992 over 3000 custom-made cemented titanium femoral components have been implanted during total hip replacement in our centre.

Stems are machined using CAD-CAM. Measurements are made from screened AP and lateral x-rays of known magnification. Normal joint centre is recreated by controlling offset and vertical height of the femoral component.

Method: Joint centre and limb length were analysed radiologically in consecutive 100 patients following total hip replacement for unilateral arthritis. Joint centre was defined relative to the pelvis and femur.

The anatomical axis and offset of the femur were defined using a screened x-ray of known magnification taken to show maximum offset. Femoral centre height was defined relative to the greater trochanter.

Results: In general, acetabular joint centre was placed medial and high, tending to reduce limb length slightly. Conversely, on the femoral side the tendency was to leave the component proud, producing an increase in limb length. Most patients had limb length restored to within 6mm of normal.

This study confirms the effectiveness of the Belfast Custom Stem in restoring joint centre and limb length.

Dislocation of the polyethylene-rotating platform is a recognised complication of LCS knee arthroplasty.

We report ten cases of rotating platform dislocation out of 2151 primary total knee arthroplasties (0.5%) performed to date in our unit.

Of the ten cases (3 male: 7 female), six patients had a preoperative valgus deformity, two had a varus deformity and the remaining two patients were in neutral alignment, although the wear was predominantly within the lateral compartment. Two patients also had a previous patellectomy on the side of the platform spinout.

Of the ten cases, six patients were symptomatic as a result of their platform dislocation. The remaining four patients were asymptomatic and mobilising without any difficulty. In these patients, the dislocated platform was diagnosed on x-ray at outpatient review. Time to detection of the platform dislocation ranged from six days to two years.

Three patients required revision of their original insert to a larger, deeper dish insert. Three were managed by open reduction of the original insert. Of the remaining patients, one was managed successfully by closed reduction, one required an arthrodesis and one had the tibial insert cemented to the tibial tray. All patients at latest review have a functional and stable knee joint.

In conclusion, we feel that surgical error was to blame for the majority of our ten cases. Furthermore, we emphasise the importance of producing equal and balanced flexion and extension gaps at the time of knee arthroplasty in order to prevent mobile bearing dislocation. A novel technique for reducing a dislocated rotating platform is also described.

Periprosthetic fractures are a recognised complication of total knee arthroplasty. They may occur intraoperatively or postoperatively and risk factors have been identified which may predispose an individual to such a complication.

We report seven cases of periprosthetic tibial fractures following LCS total knee arthroplasty, a complication only encountered by the senior author following a change in practice from a cemented implant to a cementless one.

In light of this previously unreported complication in our unit, we have attempted to identify common features within this group of patients, that may have contributed to fracture occurrence.

Statistical analysis revealed a highly significant risk of periprosthetic tibial fracture in those patients with a preoperative neutral or valgus knee. Age, gender and diagnosis did not appear to significantly increase the risk of fracture. All patients displayed evidence of reduced bone mineral density in the lumbar spine and femoral neck regions on dual energy x-ray absorptiometry scanning.

We feel that those patients with a preoperative neutral or valgus knee and local evidence of osteopenia represent a high-risk group, in whom particular care in alignment should be taken. In this group it may also be preferable to have the tibial component inserted with cement fixation.

Isolated patello-femoral osteoarthritis has been reported to occur in approximately 5% of patients with gonarthrosis of the knee. We present the results of the surgical management of this disorder in our unit. Thirty-one patients (33 knees) with symptomatic patello-femoral osteoarthritis and minimal tibio-femoral changes underwent LCS total knee replacement without patellar resurfacing.

Average age was 73 years (range, 58–89 years) with a female to male ratio of 5: 1. Average follow-up was 20 months (range, 12–40 months). All except four patients had grade 3 or 4 patello-femoral osteoarthritis according to the classification by Sperner et al.

Preoperatively, all patients had significant knee pain. Sleep disturbance was reported in 21 patients. All but 10 patients required walking aids. Average range of motion was 108° (range, 80°–125°).

At latest review, 21 knees are pain-free, the remaining 12 knees describing only occasional knee pain. Two patients continue to have night pain. Average range of motion was 104° (range, 700 – 135°). Lateral patellar tilt improved in all but five knees by an average of 7° (range, 10–26°). Patellar congruency improved in all but three knees by an average of 18% (range, 3–63%). None of the patients to date have required revision surgery. We suggest that knee arthroplasty without patellar resurfacing is an effective option in older patients with isolated patello-femoral osteoarthritis.