Aim

Chronic bone infections and infected fractures are often treated with excision of the dead bone and implantation of biomaterials which elute antibiotics. Gentamicin has been a preferred drug for local delivery, but this could induce renal dysfunction due to systemic toxicity. This is a particular concern in patients with pre-existing chronic renal disease treated with new antibiotic carriers which achieve very high peak levels of gentamicin in the first few days after surgery.

Introduction

The treatment of chronic bone infection often involves excision of dead bone and implantation of biomaterials which elute antibiotics. Gentamicin is a preferred drug for local delivery, but its systemic use carries a well-established risk of nephrotoxicity. We aim to establish the risk of renal injury with local delivery in a ceramic carrier.

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.

Periprosthetic joint infections (PJI) continue to be a diagnostic challenge for orthopedic surgeons. Chronic PJI are sometimes difficult to diagnose and occasionally present in a subclinical fashion with normal CRP/ESR and/or normal joint aspiration. Some institutions advocate for routine use of intraoperative culture swabs at the time of all revision surgeries to definitively rule out infection. The purpose of this study is to determine whether routine intraoperative cultures is an appropriate and cost effective method of diagnosing subclinical chronic PJI in revision joint replacement patients with a low clinical suspicion for infection.

We performed a retrospective chart review and identified 33 patients that underwent revision hip or knee replacement from a single surgeon over a five-month period. The AAOS guidelines for preoperative PJI workup were followed. 13 patients were diagnosed preoperatively with infection and excluded from the study. 20 patients underwent revision joint replacement and three separate cultures swabs were taken for each patient to help in determining true-positive cultures. Infectious Disease was consulted for all patients with any positive culture. Culture results were reviewed. At our hospital, the cost billed to insurance for a single culture is $1,458.58. We did not calculate the cost of the consultant fee.

Three (15%) of the 20 revision arthroplasty patients had a single positive culture. Infectious Disease consultants diagnosed all three of these positive cultures as contaminants. None of the patients had a true-positive intraoperative culture. The total cost billed by the hospital to obtain these cultures in all 20 patients was $87,514.80

In our study, obtaining a set of three intraoperative cultures for those patients with a negative preoperative infection workup was not only cost prohibitive but did not diagnose a single subclinical infection. Studies to find other more reliable, accurate, and cost effective alternatives to diagnose PJI are warranted.

In patients undergoing revision hip or knee arthroplasty with a low preoperative clinical suspicion for infection, it does not seem that routine intraoperative culture swabs are necessary or cost effective method for diagnosing subclinical periprosthetic joint infection.

Aim

To assess the accuracy of predicted and actual cut alignment from PMCB versus intra-operative computer navigation.

Purpose: To determine if oral midazolam reduces the anxiety of children undergoing removal of percutaneous Kirschner wires (K-wires) from the distal humerus in the Orthopaedic Outpatient Department.

Methods: This was a prospective double blind, randomised controlled trial. 46 children aged between 3 and 12 years who had supracondylar fractures of the distal humerus internally fixed with K-wires were randomised into 2 groups. 0.2mg/kg oral midazolam (active group) or the same volume of an oral placebo (control group) was administered 30 minutes prior to removal of K-wires.

Venham Situational Anxiety Score was performed before and immediately after removal of K-wires. University College London Hospital sedation score was recorded every 20 minutes.

Results: 42 children with an average age of 7.1 years (range 3.6–12.3 years) had complete documentation for analysis. The two groups had similar demographics. All wires were removed in the clinic with or without midazolam.

There was no significant difference in anxiety scores between the groups either before or after wire removal. The change in scores was not significantly different between the 2 groups. However, 45% of children in the active group had reduced anxiety levels in the active group compared to 18% of children given placebo but this difference was not significant (p=0.102). No child was excessively sedated but one in the active group became agitated and restless.

Conclusions: The anxiety scores before and after wire removal in the active group were not significantly different from the placebo group scores. We do not recommend the routine administration of midazolam (0.2 mg/kg) to all children requiring k-wire removal in the outpatient department.

Aim: To develop a flexion jig that would reliably hold the post-op knee in fixed flexion for a defined time period and determine its influence on peri-operative blood loss, transfusion, pain, and complications (specifically nerve palsy)following TKA.

Methods/Results: A previous study in this department showed immediate postoperative flexion to significantly reduce blood loss following TKR. Following this study, time in flexion was increased to 12 hours in an attempt to further reduce blood loss., some patients then developed a painful lower limb nerve palsy. This palsy was caused by pressure from the jig in the popliteal fossa/calf on nerves. The design of the jig was altered to remove pressure from these areas. Because of this design change, we were unsure whether the new jig would have the same blood saving effect, necessitating a new study.

This prospective randomised controlled trial recruited 420 patients into 3 equal groups: extension, 3 & 6 hrs flexion.

This trial found a significant reduction in blood loss(12%, p=0.006) and length of stay(1/2 day, p=0.006) in the 6 hour flexion group, compared the extension group.

There was no significant difference in pain or complication rates (excluding nerve palsy).

2 patients in the 6 hour group had postoperative nerve palsy, however, this palsy was sensory only and markedly different to that found previously. Although the palsy rate in this study is similar(1.4%) to quoted literature rates (1.3%) for TKA, it is difficult to know if the jig was the cause of palsy as the there was a difference between those caused by the old metal jig (painful) and those in this study (sensory loss only).

Conclusion: The results of this study show post-op flexion for 6 hours to significantly reduce perioperative blood loss. Palsy was reduced to match rates as quoted in the literature.

Irradiating allograft bone may compromise the mechanical stability of the prosthesis-bone construct, potentially having adverse effects on the outcome of femoral impaction grafting at revision hip replacement. This in vitro study aimed to determine the effect of irradiation of allograft bone used in femoral impaction grafting on initial prosthesis stability.

Morsellised ovine femoral head bone was irradiated at 0 kGy (control), 15 kGy and 60 kGy. For each group, six ovine femurs were implanted with a cemented polished double taper stem following femoral impaction bone grafting. Dynamic hip joint loading was applied to the femoral head using a servo-hydraulic materials testing machine. The primary outcome was stem micromotion. Tri-axial micromotion of the stem relative to the bone at two sites was measured using linear variable differential transformers and non-contact laser motion transducers. Statistical analysis was performed using SPSS.

Compared to the control and 15 kGy groups, specimens in the 60 kGy group demonstrated statistically significant greater micromotion in the axial, antero-posterior and medio-lateral axes. A multi-factorial post-hoc power analysis based on the overall effect of group size indicated a power of 0.7. There was no difference in micromotion between the control and 15 kGy groups. The average micromotion in the axial axes was 63μm in the control and 59μm in the 15 kGy group.

The results of this study suggest that a maximum irradiation dose of 15 kGy may not affect initial prosthesis stability following femoral impaction grafting in this model and provide the basis for us to now proceed to in-vivo studies examining the effect of irradiated bone on implant stability over time.

Our purpose wasto determine if oral midazolam reduces the anxiety of children undergoing removal of percutaneous Kirschner wires (K-wires) from the distal humerus in the Orthopaedic Outpatient Department.

This was a prospective double blind, randomised controlled trial. 46 children aged between 3 and 12 years who had supracondylar fractures of the distal humerus internally fixed with K-wires were randomised into 2 groups. 0.2mg/kg oral midazolam (active group) or the same volume of an oral placebo (control group) was administered 30 minutes prior to removal of K-wires.

Venham Situational Anxiety Score was performed before and immediately after removal of K-wires. University College London Hospital sedation score was recorded every 20 minutes.

42 children with an average age of 7.1 years (range 3.6–12.3 years) had complete documentation for analysis. The two groups had similar demographics. All wires were removed in the clinic with or without midazolam.

There was no significant difference in anxiety scores between the groups either before or after wire removal. The change in scores was not significantly different between the 2 groups. However, 45% of children in the active group had reduced anxiety levels in the active group compared to 18% of children given placebo but this difference was not significant (p=0.102). No child was excessively sedated but one in the active group became agitated and restless.

The anxiety scores before and after wire removal in the active group were not significantly different from the placebo group scores. We do not recommend the routine administration of midazolam (0.2 mg/kg) to all children requiring k-wire removal in the outpatient department.

Purpose: The study objective was to measure ‘posterior condylar offset’ (PCO), and tibial slope (TS) following cruciate-sacrificing total knee arthroplasty (TKA), and determine any influence on one-year flexion values following cruciate-sacrificing Total Knee Arthroplasty.

The term ‘posterior condylar offset’ (PCO) is defined as the distance from a line projected along the posterior cortex of the femur to the maximum convexity of the posterior condyles. Its magnitude has been found to correlate with final flexion following PCL-retaining TKA, if reduced by more than 3mm post-operatively. (1)

Tibial slope is the angle between a line drawn parallel to the articular surface and a line drawn perpendicular to the long axis of the tibia on a lateral radiograph. Increasing the tibial slope in PCL-retaining TKA has been shown to improve maximal flexion of an average 1.7 degrees flexion for every extra degree on the tibial slope. (2)

Method: We reviewed the pre and post-operative radiographs of 69 patients who had undergone cruciate-sacrificing TKA. All cases were performed by a single surgeon using the same operative technique. Preoperative and postoperative true lateral radiographs were used to measure the change in PCO and the TS. Pre-operative and one-year flexion was measured using a goniometer.

Results: There were 26 males and 43 females. Mean age was 68 years (range 38 – 87). 67 of the patients had a primary diagnosis of OA, the remaining 2 patients RA.

The mean pre-operative PCO was 25.9 mm (21 – 35), whilst the mean post-operative PCO was 26.9 mm (21 – 34). The difference in preoperative and postoperative PCO ranged from −6 mm to + 5 mm (average, +1mm).

Three patients 4% had more than 3mm reduction in their PCO following TKA (range −4mm to −6mm). 16% had their post-operative PCO increased by more than 3mm (range 4mm – 5mm). The remaining 80% had their PCO restored to within 3mm either way.

The mean post operative tibial slope was 6.6° with a range of 5–9°, 38% measuring 6°, 21% at 7°, 17% at 8°and 5° and the remaining 7% at 9°.

Of the three patients whose PCO was reduced by more than 3mm, one had the same flexion 1 year postoperatively, one had an increase of 14 degrees, and unfortunately the third died before their 1 year review.

Using regression analysis, the strongest predictor of one-year flexion for this study group was the preoperative flexion value. The change in PCO and angle of the tibial slope had no significant influence on one-year flexion.

Conclusion: It would appear that the LCS technique permits satisfactory restoration of PCO and consistent tibial slope as only 4% of patients in this study had a decrease in PCO of more than 3mm and the range of tibial slope was within 5°. We feel these parameters are important however in this study it did not have significant influence on final flexion.

Introduction: Potential benefits cited for minimally invasive total hip arthroplasty (THA) include reduced peri-operative blood loss, less post-operative pain, earlier mobilisation and a shortened hospital stay. Sceptics, however, are concerned about the widespread introduction of a new surgical technique in the absence of objective scientific evidence. The ever-increasing pressure on healthcare budgets by an ageing population makes developments in surgical technique that allow earlier mobilisation and reduced length of hospital stay highly desirable. The aim of this study was to investigate whether a minimally invasive technique in THA would result in a reduced length of hospital stay compared to a standard incision of 16cm.

Materials and Methods: 219 patients were randomised to either a minimally invasive (less than or equal to 10cm) or standard (16cm) incision group. Patients were blinded to their incision length. Anaesthetic and post-operative analgesic protocols were standardised. A single surgeon performed all operations using an uncemented cup and a cemented stem. Post-operative physiotherapy was standardised with the physiotherapists also blinded to incision length. Patients were discharged when safely able to transfer and mobilise with a walking aid.

Results: There was no statistically significant difference in mean length of stay following surgery. This was 3.65 days (SD 2.04) for the mini-incision group and 3.68 days (SD 2.45) for the standard incision group (p=0.94). 32% of patients (35/110) in the standard incision group were able to go home on day 2 compared to 27% (29/109) in the mini-incision group. Using logistic regression analysis, the patient variables most significantly associated with a probability of discharge within 3 days of surgery were patient age (Wald=33.36, p< 0.0001) and pre-operative haemoglobin (Wald=10.53, p=0.001).

192 patients (88.5%) were discharged to their own homes with the main determinant of discharge to the patients’ own home being the availability of adequate family support.

Conclusion: Total hip arthroplasty performed through a single incision minimally invasive approach does not reduce the length of hospital stay compared to THA performed through a standard incision of 16cm.

Purpose: The objective of this study was to examine the relationship between aspirin and other non-steroidal anti-inflammatory drugs (NSAIDS) on postoperative blood loss following Total Knee Arthroplasty

Methods: We prospectively examined the pre-operative consumption of aspirin and NSAIDS and haematological parameters of 50 consecutive patients undergoing Total Knee Arthroplasty. 22 (44%) patients were on aspirin only, 17 (34%) patients on aspirin and another NSAID and 11 (22%) patients were taking neither aspirin nor a NSAID. (All patients received 150mg of aspirin the evening before surgery as DVT prophylaxis).

Results: The average pre-operative haemoglobin of the group taking aspirin and a NSAID, aspirin only and neither aspirin nor NSAID group was 12.9g/dl, 13,8g/dl and 13.49g/dl respectively. The drop between their pre-operative level and Day 3 Haemoglobin level was 3.788g/dl, 4.45g/dl and 4.28g/dl respectively.

The same trend was reflected in the PCV drops of 0.111, 0.133 and 0.1273 respectively. Transfusion rates for the three groups showed that those on aspirin and another NSAID had the highest rate with an average of 0.235 units per patient compared to 0.136 for those on aspirin only and 0.10 for those on neither aspirin nor NSAID.

Discussion: These findings indicate that the ingestion of aspirin or a NSAID preoperatively does not increase the amount of blood loss following total knee arthroplasty (TKA). The higher transfusion rates in the aspirin and NSAID group is because of the lower preoperative haemoglobin as compared to the other groups studied.

Conclusion: Observation of transfusion trends within our unit has shown a transfusion rate of 18% in patients with a preoperative Haemoglobin level of greater than 13.0g/dl as compared to 48% with a haemoglobin level of 13.0g/dl or less (review of 180 consecutive patients undergoing Total Knee Arthroplasty).

The ingestion of aspirin and NSAID does not increase blood loss following TKA but significantly have a lower preoperative Hb level. We feel that pre-operative Haemoglobin levels are the best predictors of transfusion requirements following total knee arthroplasty.

Introduction: Surgical injury induces a systemic inflammatory response proportional to the severity of the insult. An appropriate response maintains homeostasis and allows wound healing while an excessive response may trigger an inflammatory cascade resulting in the systemic inflammatory response syndrome (SIRS). Tissue injury results in cytokine release, which in turn stimulates the production of acute phase proteins such as C-reactive protein (CRP), fibrinogen, complement C3 and haptoglobin. Serum CRP levels rise following total hip arthroplasty (THA), peaking on the second to third post-operative day. Local effects of the inflammatory response manifest as the cardinal signs of inflammation, which include swelling.

One of the potential benefits cited for minimally invasive THA is reduced soft tissue trauma resulting in less post-operative pain, less swelling and earlier mobilisation. Objective evidence, from well designed prospective studies, for these benefits remains lacking. The aim of this study was to investigate whether a minimally invasive technique in THA results in a reduced acute phase response and reduced post-operative swelling compared to THA performed through a standard incision of 16cm.

Materials and Methods: 219 patients were randomised to either a minimally invasive (less than or equal to 10cm) or standard (16cm) incision group. Patients were blinded to their incision length. Anaesthetic and postoperative analgesic protocols were standardised. A single surgeon performed all operations using an uncemented cup and a cemented stem. Baseline CRP levels were measured pre-operatively and re-measured on the second post-operative day to determine whether there was any difference in the magnitude of the inflammatory response between the two patient groups. Pre-operative measurements were also made of the mid-thigh circumference on the affected side. The mid-thigh circumference was re-measured at 48 hours to assess postoperative swelling.

Results: There was no statistically significant difference in the mean serum CRP levels at 48 hours, which were 135.7mg/L (SD 51.2) for the mini-incision group and 125.6mg/L (SD 59.4) for the standard group (p=0.20). With respect to post-operative swelling, the mean increase in mid-thigh circumference at 48 hours was 4.3cm for the mini-incision group and 3.7cm for the standard group. The difference between the two groups was not statistically significant (p=0.30)

Conclusion: THA performed through a single incision minimally invasive approach does not result in reduced post-operative swelling or a reduced acute phase response, as measured from post-operative CRP rise, compared to THA performed through a standard incision of 16cm.

Introduction: Hip fractures affects more than 65,000 people in the UK each year and this number is increasing. The standard treatment is insertion of either a dynamic hip screw or hemiarthroplasty depending on fracture configuration. Because of their advanced age, associated co-morbid factors as well as having had an implant inserted, hip fracture patients are at increased risk of developing post-operative wound infections. The infection rate for hip fracture surgery is quoted at 0.6 – 3.6%¹.

Methods: We carried out a retrospective study of the readmission rate due to wound infection following treatment of their fractured neck of femur. 20 patients (16 females and 4 males) were identified over a 24 month period out of a total 1786 femoral neck fractures treated (1.1%).

Results: 11 patients re-admitted with a wound infection had had a hemiarthroplasty fixation, 9 following insertion of a DHS. 7 patients (0.4%) had a superficial wound infection (3 hemi, 4 DHS) and 13 (0.7%) a deep wound infection (8 hemi, 5 DHS). Treatment for the superficial wound infections included 6 patients requiring IV antibiotics and 1 requiring washout and resuturing of the wound.

Treatment of deep wound infections included 6 who had a Girdlestone procedure, 2 had wound washout, debridement and 2 who had removal of DHS. All received IV antibiotics. 2 patients were deemed unfit for surgery and received IV antibiotics only.

3 patients with a deep wound infection (23%) died (2 deemed unfit for surgery, and 1 Girdlestone) during their admission. 85% of the readmissions had an ASA score of three or over. We looked at the length of operation time and found that 15 took less than 45 minutes, 4 took between 45 and 60 minutes and one took over 60 minutes. Three of the operations which took over 45 minutes developed deep infections.

Conclusion: Fractured neck of femur accounts for a large proportion of fracture admissions. Accepted methods of treatment carry significant infection rates. Superficial wound infections can in the majority be treated with IV antibiotics. Deep wound infections carry a significant mortality rate. Operating time should be within 45 minutes where possible to reduce the risk of deep infection. Post-operative wound infections are associated with an ASA grade of 3 or greater.

Introduction: It has been shown that acrylic bone cement is weakened by its porosity, which enhances the formation of micro-cracks that contribute to major crack propagation. It has also been observed, that mixing procedures play a significant role in determining the quality of bone cement produced. A high degree of porosity is found to exist in cement that is inadequately mixed.

Currently mixing system allow for the preparation of the bone cement under the application of a vacuum in a closed, sealed chamber by means of a repeatable mixing action. These systems are perceived to be repeatable, reliable, and operator independent. The objective of this study is to evaluate the quality and consistency of acrylic bone cement prepared by scrub staff in an orthopaedic theatre using a commercially available third generation vacuum mixing syringe, in terms of the level of voids within the cement microsturcture.

Materials and Methods: The mixing devices were stored at 23°C ± 1°C for a minimum of 24 hours prior to mixing. The acrylic bone cement (Palacos R® with gentamicin, Biomet Merck, UK) was stored at 4°C ± 1°C for a minimum of 24 hours prior to mixing.

Bone cement was mixed using a commercially available third generation mixing device (vacuum = −550mmHg) at Musgrave Park Hospital, Belfast, Northern Ireland. The cement was mixed according to the device manufacturers’ instructions for use. Mixing was carried out during a joint replacement surgery by a number of experienced theatre scrub staff (n = 35). The cement remaining at the end of the procedure was allowed to cure within the delivery nozzle, made from linear low-density polyethylene (LLDPE) and having an internal diameter of 10mm. 205 nozzles were collected post-operatively and stored at 23°C ± 1°C prior to testing. The percentage porosities were determined by measuring the apparent densities based on Archimedes principle and, as a direct result; it was possible to calculate the mean percentage porosities.

Discussion: It can be observed that the majority of the theatre nurses, ie 46.8% prepared bone cement using the vacuum mixing system containing a porosity of between 2% to 4%. A cement porosity of this range would be the accepted optimum content for acrylic bone cement. However, 6.4% of the theatre nurses prepared cement demonstrating a porosity content ranging from 8–16%, which is highly unsatisfactory when you consider that the cement mixing system is perceived to be a consistent and reliable mixing device that is operator independent.

Figure 2 illustrates a bar chart representing the bone cement porosity as a function of which orthopaedic theatre the cement was prepared. There was no significance difference when comparing the quality of the cement mixed in terms of porosity with the different theatres. The mean porosity values of the cement mixed ranged between 2.5% and 5.2% depending on which theatre was used.

Conclusions: Bone cement mixed using the commercially available third generation device in theatre by 35 scrub staff was found to have a high degree of variability. Thus demonstrating that even an alleged reproducible mixing system is independent on mixing technique when used in a clinical situation by a number of users. Thus illustrating the system is not wholly user independent.

As a consequence of this investigation it is recommended that the key to ensuring high quality bone cement, with a good mechanical strength, that can be consistently prepared in theatre by scrub staff are two fold.

The orthopaedic staff must be aware of the significance of cement mixing and how it is affected by a number of factors including the type of mixing system, vacuum level applied, and mixing technique.

Purpose: The study objective was to measure ‘posterior condylar offset’ (PCO) following Low Contact Stress (LCS) total knee arthroplasty (TKA), and determine its influence on one-year flexion values.

The term ‘posterior condylar offset’ (PCO) is defined as the distance from a line projected along the posterior cortex of the femur to the maximum convexity of the posterior condyles. Furthermore its magnitude has been found to correlate with final flexion following PCL-retaining TKA, if reduced by more than 3mm post-operatively1..

Method: We reviewed the pre and post-operative radiographs of 69 patients who had undergone primary LCS TKA. All cases were performed by a single surgeon using the same operative technique. The PCO was measured from the preoperative and postoperative true lateral radiographs. Pre-operative and one-year flexion was measured using a goniometer.

Results: Of the 69 patients studied, three patients (4%) had more than 3mm reduction in their PCO following TKA (range −4mm to −6mm). Eleven (16%) had their post-operative PCO increased by more than 3mm (range 4mm – 5mm). The remaining fifty five (80%) had their PCO restored to within 3mm either way.

Of the three patients whose PCO was reduced by more than 3mm, one had exactly the same flexion 1 year post-operatively, one had an increase of 14 degrees, and unfortunately the third died before their 1 year review.

Using regression analysis, the strongest predictor of one-year flexion for this study group was the preoperative flexion value. The difference in PCO before and after TKA had no significant influence on one-year flexion.

Conclusion: It would appear that the LCS technique permits satisfactory restoration of PCO as only 4% of patients in this study had a decrease in PCO of more than 3mm. We feel restoration of PCO is important; however in this study it did not have significant influence on final flexion.

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.

Introduction: The anatomy of the proximal femur is an important factor in the design of uncemented femoral prostheses for which the quality of fixation and the associated bony remodelling depend on the primary stability and optimal transmission of forces to the proximal femur. This study looks at the variation in the diameter of the proximal femur with age and sex in a homogeneous population.

Materials and Methods: We studied standardised pre-operative antero-posterior radiographs of the proximal femur of 2,777 patients who have undergone total hip arthroplasty using a custom implant over a 10 year period. The radiographs were corrected for magnification and a measurement made of the endosteal diameter at the narrowest point of the proximal femur. These measurements were used in the design and manufacture of the custom femoral implant.

Results: Of 2777 patients, 1588 were female and 1189 male. The mean age for females was 69.9 years (Range 30–92) and for males 67.2 years (Range 34–92). The mean proximal femoral canal diameter was 12.67mm for females and 13.36mm for males.

The mean diameter of the proximal femur increased from 12.99mm in males less than 60 years to 13.47mm in those of over 60. This increase was not statistically significant (p-value 0.064, 95% CI). In females there was a statistically significant increase in the mean diameter from 11.38mm in the under 60 age group to 12.90mm in those over 60 ( p-value 0.000, 95% CI).

Conclusions: The increase in the diameter of the proximal femur with age especially in females presents a significant challenge to the design and long-term survivability of uncemented femoral components. This is more so when viewed against the already good long term results available for cemented femoral implants.

We report a series of 668 patients (699 hips) with an average follow up of 10.5 years (range, 10–11 years) following THR using a cemented custom-made titanium femoral stem and a cemented high-density polyethyl-ene acetabular component. The fate of every implant is known.

The mean age at operation was 68 years (24 – 94 years). The indication for THR was as follows: primary OA (629), RA (18), AVN (10), intracapsular femoral neck fracture (5), Perthes disease (3), developmental hip dysplasia (2) and SUFE (1). The mean pre-operative Harris Hip Score was 19 (range 10 – 42).

One hundred and seventy-four patients (26%) were deceased at the time of their 10-year review. Four hundred and ninety-four patients were subsequently reviewed of which 88 patients (13%) were assessed by telephone review as they were too frail to attend.

The average 10-year Harris Hip Score was 92 (range 43 – 100). The average 10-year Oxford Hip Score was 19 (range 12 – 46). 99.2% reviewed at 10 years stated that they were satisfied with their THR.

Revision surgery occurred in 21 cases (3%). Seventeen femoral components were revised for infection, one for recurrent dislocation and one was iatrogenically loosened during socket revision. There were no cases of revision for aseptic loosening of the stem. Dislocation occurred in 18 cases, of which 4 became recurrent (0.6%). Six patients had a postoperative sciatic nerve palsy (0.9%) with 4 making a full recovery. There was one case of femoral nerve palsy. Eleven patients developed a DVT (1.6%). Six patients had a PE (0.9%) all of which were non-fatal. There were 16 deep and 3 superficial wound infections. Thirty-eight patients had symptomatic trochanteric bursitis post-surgery.

In conclusion, the 10-years results of the custom femoral stem are encouraging with an overall high level of patient satisfaction.

Introduction: The use of minimal incision THR is increasing. The purpose of this study is to determine the effects of a change in operative technique from a standard incision to a minimally invasive incision at primary THR on peri-operative blood loss, analgesia requirement, length of stay, and complication rate. Two consecutive groups are compared.

Materials and methods: All patients who underwent a primary THR (posterior approach) by the senior author during a 3month period before and after a change in technique from a standard to a minimal incision were identified. 202 patients were analysed: 105 standard incisions and 97 minimal incisions. A retrospective chart review was used to collect age, height, weight, BMI, diagnosis and length of stay for each patient. Estimated peri-operative blood loss in units of blood was calculated by a validated formula. Morphine usage by PCA in the first 24hours post-operatively was recorded. Complications were identified.

Results: There was no significant difference in the mean age, height, weight or BMI between the 2 groups. Predominant diagnosis was primary osteoarthritis. Mean wound length for the standard incision was 16.6cms. Mean wound length for the minimal incision was 11cms. There was no difference in length of stay, mean 5.4days. There was no difference in morphine usage by PCA in the first 24hours, mean 39.4mgs.

Average estimated peri-operative blood loss for the standard incision group was 3.45 units and for the minimal incision group was 3.05 units (statistically significant, p-value 0.039, 95%CI). One patient after minimal incision had a superficial wound infection, which responded to oral antibiotics. There was one dislocation (standard incision).

Conclusions: Peri-operative estimated blood loss was less with a minimal incision but there was no difference in length of stay or analgesia requirement. A prospective RCT is now underway to determine the clinical efficacy of minimally invasive THR.