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.

Following the recent publication in April 2007 of NICE guidelines on venous thromboembolism, we report our practice and experience of VTE in adult hip and knee arthroplasty.

It is generally agreed that the 2 major complications of VTE are sudden death as a result of pulmonary embolism and post thrombotic syndrome. NICE guide-lines make 2 assumptions:

That chemical and mechanical prophylaxis can reduce these complications

Methods and Results: We have studied a large cohort of patients who had Aspirin only as chemical prophylaxis to determine the incidence of clinical thromboembolism before and after discharge and the mortality from PE at 90 days.

We performed a retrospective analysis of consecutive patients undergoing primary total knee and hip replacement from November 2002 to November 2007. In total 2050 patients had total knee replacement and 2203 patients had total hip replacement. All patients were treated at one specialist centre under the care of one surgeon. Data was complete and accurate for all patients at 90 days post-operatively.

Standard practice was the use of 150mg Aspirin from Day 1 post-operatively for a total of six weeks combined with spinal anaesthesia and early mobilisation.

The overall rate for Fatal Pulmonary embolism 0.07% (3/4253), overall death rate 0.31%(13/4253), for treated non-fatal PE 0.66% (28/4253) and for treated above knee DVT was 0.33%(14/4253).

Conclusion: Our data suggests that fatal pulmonary embolism is not common and does not account for most deaths following total hip and knee arthroplasty. We suggest there is no evidence that chemical/mechanical prophylaxis reduces the risk of sudden death from PE following elective primary joint replacement and with modern surgical practice elective hip and knee replacement should no longer be considered high risk procedures.

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: A critical determinant of early dislocation following total hip arthroplasty (THA) is correct positioning of the acetabular component. This challenging aspect of THA has not been lessened by the introduction of more minimally invasive techniques. In this paper we introduce a simple and reproducible technique, which uses the transverse acetabular ligament (TAL) to determine cup orientation. We have used this technique as the sole method of cup orientation in our last 1000 consecutive primary total hips.

Methods: One thousand consecutive patients were studied in order to determine the prevalence of early dislocation (within 3 months) following acetabular component placement determined by reference to the transverse ace-tabular ligament. All patients underwent primary total hip arthroplasty via a posterolateral approach with a posterior repair.

Results: At a minimum follow-up of 9 months (range 9–39 months) 6 of the 1000 hips (0.6%) had dislocated.

Conclusion: Although multiple factors are known to contribute to this rate correct placement of the acetabular component is critical. As our results compare favourably with other published series where a posterior repair has been performed by extrapolation we feel that that the TAL does provide an acceptable method of determining cup orientation. The fact that it is independent of patient position on the table and is easy to locate with a minimally invasive approach makes it an attractive method.

Between April 1992 and July 2005, 310 posterior lip augmentation devices were used for the treatment of recurrent dislocation of the hip in 307 patients who had received primary total hip replacements (THRs) using Charnley/Charnley Elite components with a cemented acetabulum. The mean number of dislocations before stabilisation with the device was five (1 to 16) with a mean time to this intervention from the first dislocation of 3.8 years (0 days to 22.5 years). The mean age of the patients at this reconstruction was 75.4 years (39 to 96).

A retrospective clinical and radiological review was carried out at a mean follow-up of six years and nine months (4.4 months to 13 years and 7 months). Of the 307 patients, 53 had died at the time of the latest review, with a functioning THR and with the posterior lip augmentation device in situ. There were four revisions (1.3%), one for pain, two for deep infection and one for loosening of the acetabular component. Radiolucent lines around the acetabular component increased in only six cases after insertion of the device which was successful in eliminating instability in 302 patients, with only five further dislocations (1.6%) occurring after its insertion.

Ensuring the accuracy of the intra-operative orientation of the acetabular component during a total hip replacement can be difficult. In this paper we introduce a reproducible technique using the transverse acetabular ligament to determine the anteversion of the acetabular component. We have found that this ligament can be identified in virtually every hip undergoing primary surgery. We describe an intra-operative grading system for the appearance of the ligament. This technique has been used in 1000 consecutive cases. During a minimum follow-up of eight months the dislocation rate was 0.6%. This confirms our hypothesis that the transverse acetabular ligament can be used to determine the position of the acetabular component. The method has been used in both conventional and minimally-invasive approaches.

Objective: To determine if a standard course of outpatient physiotherapy improves the range of knee motion following primary total knee arthroplasty.

Design: One hundred and fifty patients undergoing primary total knee arthroplasty were recruited and randomly assigned into two groups. Group 1 received a course of physiotherapy with a standard protocol over a six week period within 4 weeks of hospital discharge. Group 2 received no outpatient physiotherapy. All patients received inpatient physiotherapy for the length of their hospital stay. Range of knee motion was measured using a goniometer by members of the outcome team blinded to the randomisation. Validated knee scores (Oxford knee and Bartlet patellar) were collected. An SF12 health questionnaire was used as a generic outcome measure.

Results: Both groups were equally matched by age and sex. Although patients in Group 1 achieved greater range of knee motion than those in Group 2 this was not statistically significant. No difference was also noted in any of the outcome measures used.

Conclusion: We conclude that in patients undergoing primary total knee arthroplasty, inpatient physiotherapy with good instructions and a well-structured home exercise regime can dispense with the need for outpatient physiotherapy.

Objective: To examine the impact of aspirin and non-steroidal anti-inflammatory drugs (NSAIDs) on preoperative haemoglobin levels and perioperative transfusion rates in patients undergoing total knee arthroplasty (TKA).

Methods: We examined the pre-operative haemoglobin (Hb) and haematocrit (Hct) of a consecutive series of 81 patients, looking at the relationship between the pre-operative use of Aspirin/NSAIDs on preoperative Hb, postoperative Hb deficit and the perioperative transfusion rate. A single surgeon performed all procedures using an LCS TKR (Depuy, Leeds UK). A standardised transfusion protocol was used.

Results: The patients were grouped according to their pre-operative use of aspirin or a NSAID, singly or in combination. The patient groups are as shown in the table below. All groups were comparable for age, BMI and ASA grade.

Results show a significantly higher transfusion rate (p=0.048) in the group of patients who received a combination of aspirin and a NSAID compared to the other groups. The patients on aspirin or a NSAID alone also had an increased transfusion rate but the increase was not statistically significant (p=0.12 and p=0.07 respectively).

Conclusion: The use of both aspirin and an NSAID in combination leads to a lower preoperative Hb and an increased post-operative transfusion requirement following total knee arthroplasty.

Current methods for restoring or preserving limb length following total hip arthroplasty are anatomically inaccurate, as they do not consider acetabular and femoral height independently. In order to address this, we present and evaluate a technique that uses the transverse acetabular ligament to control the vertical height of the acetabular component and a caliper that controls the vertical placement of the femoral component within the femoral canal. Limb lengths were measured in 200 patients who had undergone primary total hip arthroplasty using this technique. Using this method, 94% had a post-operative limb length inequality that was 6 mm or less when compared to the normal side (average +0.38 mm). The maximum measured limb length inequality was ± 8 mm.

Background: The positioning of the acetabular component is of critical importance in total hip arthroplasty. Due to the orientation of the acetabulum and limitations of observation imposed at the operative site mal-positioning is common. We believe that by utilising the transverse acetabular ligament (TAL) and acetabular labrum, we are able to anatomically position our cup. In this study, we evaluate the correlation between placement of the acetabular component by reference to the TAL and the acetabular labrum with the taught safe zones for cup placement.

Method: 7 embalmed hips were studied. Following disarticulation the labrum and TAL were digitised and their plane was calculated. Orientation of cup placement in this plane was calculated from a pre-dissection pelvic CT.

Results: The plane of the labrum/TAL varied between 5–26° of anteversion and 32–59° of inclination. Interob-server differences in acetabular cup placement based on the TAL/labral plane indicate reasonable coherence. Almost all components were inside the documented “safe zone” 0–40° of anteversion and 30–55° of inclination of placement.

Conclusion: The acetabular labrum and TAL form a plane that reflects the documented “safe zones” for acetabular component placement. We feel that this plane allows a surgeon to determine optimal patient specific acetabular component placement, irrespective of patient position.

Isolated patellofemoral osteoarthritis has been reported to occur in approximately 5% of patients with gon-arthrosis of the knee. A number of options are available for the surgical management of these individuals. We reported the short-term outcomes on thirty three patients (33 knees) with isolated patellofemoral osteoarthritis who underwent LCS total knee arthroplasty (TKA) without resurfacing who had been operated on between 1996 – 1999¹.

Barrack et al² in 2001 reported on the incidence of anterior knee pain in two groups of TKA patients, one with patella resurfacing and one without. They reported an increase incidence of anterior knee pain in both groups.

We now report the longer-term outcomes with an average follow-up of 80.2months (range 54–94 months). At latest review, 9 patients experienced night time pain, all describing it as improved from their preoperative level. Twelve patients walked with the use of a walking aid, compared with 21 preoperatively. Disease specific scores at latest review showed improved outcome measures at latest review.

We also report our outcomes in an additional fifty-five patients (59 knees) with isolated patellofemoral osteoarthritis who were treated between 1999–2004 receiving an LCS total knee arthroplasty without patellar resurfacing. Our preliminary findings suggest that this technique continues to be an option in the management of the older patient with isolated patellofemoral osteoarthritis.

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: Historically, it has been accepted that the pain associated with arthritis of the hip is usually located in the groin, anterior and lateral thigh with occasional radiation to the anterior knee. Patients complaining of thigh pain that extends below the knee are often considered to have a degenerative lumbar spine as the cause for their lower limb symptoms and total hip replacement (THR) may not be offered.

Following review of data regarding the preoperative distribution of pain in 2000 patients attending for hip replacement, it was noted that 40% of these patients had complained of pain at or below the knee.

We proposed to prospectively investigate the severity and location of pain in patients attending for THR and assessed how this distribution of pain altered following surgery. We also proposed to examine the distribution of radiological wear preoperatively and assess if there is any relationship between localisation of pain, and the severity or distribution of the radiological wear pattern.

Methods: 200 consecutive patients undergoing primary THR completed a questionnaire regarding the location and severity of their pain. Pain was localised to one or more of nine areas extending from low back to the foot. The localisation of pain was quantified as to severity using a visual analogue score. Questionnaires were completed both 4 weeks preoperatively and subsequently at a 3-month review clinic.

All patients underwent a standardised preoperative AP and Lateral x-ray. The AP film was divided into three areas, and the lateral film was divided into 5 areas. Each zone was assessed as to the severity of wear pattern and graded from 1–3 (no change in joint space, decreased joint space, femoral or acetabular destruction).

Results: The 200 patients complained of pain in a total of 980 areas preoperatively and 105 areas postoperative. 70% of the patients had complete relief of all pain at 3 months. The most common area of pain identified by patients was to the anterior aspect of the knee (82%), followed by pain at the greater trochanter and groin. 55% patients complained of pain extending to below the knee, mostly over the anterolateral aspect of the leg. Only 7% of these patients continued to complain of any below knee pain postoperatively, and all of these patients still had some relief of their below knee pain at review.

With regard to the frequencies and severity of x-ray changes, zone-1 (34%) was most commonly severely damaged with femoral and/or acetabular destruction in the AP film, with the anterior and anterolateral areas being most commonly affected areas in the lateral film (20% and 19% respectively).

When the distributions and severities of x-ray changes were correlated with the distribution of pain localised pre and postoperatively we were unable to show any association between the degree of radiological wear in any one zone and the locatin of pain identified by the patient. In fact, there was a normal distribution to the severity of radiological damage between each of the zones and localisation of pain in any of the 9 areas.

Conclusions: A significant number of patients who require hip arthroplasty have pain extending below the knee. This pain is frequently relieved following THR. The commonest area of sever hip joint wear with loss of femoral or acetabular bone is antero-superiorly. It is important to recognise this during surgery, such that action can be taken to ensure appropriate reaming such that subsequent correct tissue tension and leg lengths are achieved. We are unable to show any relationship between area of pain and area of radiological degeneration. We believe that patients who complain of pain in their back, buttock or thigh, which extends below the knee, can still benefit from total hip replacement. Patients who attend complaining of low back pain with radiation of pain down their leg should have their hips as well as their lumbar spine examined and imaged. Careful consideration should be taken before labelling the paid as being referred from degenerative back disease.

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.

Introduction Range of motion (ROM) is an important measure of outcome. A better understanding of the factors influencing ROM is important when counselling patients undergoing TKA.

Aim The aim of the study was to prospectively evaluate the influence of a number of selected variables on knee flexion at one year using the same prosthesis in a single surgeon series.

Patients and Methods 170 patients (57 males; 113 females) undergoing TKA were prospectively evaluated. The following data was recorded for each patient: age, gender, primary diagnosis, direction and magnitude of the preoperative axial deformity, BMI, cement use, preoperative and one year Oxford Knee Scores (OKS), the active and passive range of motion (ROM) preoperatively, at the end of surgery and at three month and one year review.

Results Average flexion values at each stage were as follows: preoperative (1110), end of surgery (1200), three months (1030) and one year (1070). There was a significant loss of flexion following TKA. The improvement between three months and one year however proved significant. Multiple regression analysis revealed that preoperative flexion was the strongest predictor of one-year flexion. Increasing age was also found to have a significant influence on final flexion. Gender, BMI, pre-operative OKS and cement use had no significant influence on final flexion. Patients tend to migrate towards a middle range of flexion i.e. those with poor flexion gain movement whilst those with good flexion tend to lose motion.

Conclusions Preoperative flexion is the strongest predictor of final flexion following TKA.

Introduction Fixed flexion deformity (FFD) represents a challenge during total knee arthroplasty (TKA). Furthermore, controversy exists as to the fate of FFD following TKA.

Aims The aims of this study were to determine how fixed flexion behaves in relation to surgery, factors that may influence or correlate with FFD both preoperatively and following TKA and the effect of FFD on outcome at one year.

Patients and Methods 133 patients (41 males; 92 females) undergoing TKA were prospectively studied. The following data was recorded for each patient: age, gender, primary diagnosis, direction and magnitude of the pre-operative axial deformity, BMI, preoperative and one year Oxford Knee Scores (OKS), the active and passive range of motion (ROM) preoperatively, at the end of surgery and at three month and one year review. FFD was defined as forced passive extension (FPE) greater than zero degrees.

Results Sixty-six patients (50%) had a preoperative FFD (mean, 60). At the end of surgery, this measured 10, 80 at 3 months and 40 at one year. When comparing those with a preoperative FFD to those with no FFD, there was no significant difference when assessing age, BMI or preoperative OKS. Preoperative FFD was significantly more common in males although there was no significant difference in the magnitude of FFD at any stage between males and females. There was a significant improvement in FFD at one year. Patients with a preoperative FFD were found to have significantly less flexion both preoperatively and at one year. When comparing those with FFD at one year to those with no FFD, those with FFD were significantly older and had significantly less flexion. There was no significant difference in BMI, OKS or gender.

Conclusions There is a definite trend when assessing the change in FFD with time. Correction at the time of surgery would appear to be important. Residual FFD is associated with reduced flexion at one year.

Introduction Satisfactory patellar tracking is important following total knee arthroplasty. A lateral retinacular release may be required to correct patellar maltracking but can be complicated by damage to the skin, soft tissues or patella.

Aim The aim of this study was to determine if, when using the LCS prosthesis, the rate of lateral patellar release was reduced by centering the finishing guide on Whiteside’s line as opposed to the mid-point of the femoral condyles.

Patients and Methods One hundred and ten consecutive patients (64 female, 46 male) undergoing primary total knee arthroplasty were prospectively studied. At the time of performing the champher cuts, the finishing guide was first centered on the mid-point of the femoral condyles and a mark placed on the trochlea using the needle diathermy. The finishing guide was then finally centered on the previously marked Whiteside’s line. The distance between the two marks was measured using a caliper. Following component insertion patellar tracking was checked. If required a lateral release was performed allowing the patella to track with its medial facet in contact with the medial femoral condyle.

Results Centralization of the femoral component on Whiteside’s line instead of the mid-point of the femoral condyles lateralized the component by an average of 2.7mm (range, x–ymm). This parameter was termed the patellofemoral offset (PFO). When compared to a sample of patients where the finishing guide was centered on the mid-point of the femoral condyles, the lateral patellar release rate was reduced from 25% to 18%.

The magnitude of PFO increased with age however there was no significant difference in PFO between males and females. The PFO was significantly greater for knees with a preoperative valgus deformity (p=0.006).

Conclusion Centering the femoral component on White-side’s line leads to a reduction in lateral patellar release rate during TKA.