High tibial osteotomy (HTO) is a recognised method of correction for knee joint malalignment and unicompartmental osteoarthritis. The long term results of this technique have been reported and are favourable. Autologous chondrocyte implantation (ACI-C, MACI) has also been reported to have good results It is advised that malalignment, if present, should be corrected if ACI is to be performed. Although results have been reported for either procedure separately, the outcomes of combined HTO-ACI remain unreported.

To evaluate functional outcome in a group of patients undergoing combined HTO-ACI procedures.

Twenty three patients undergoing a combined ACI-HTO procedure were identified retrospectively from a larger trial of patients undergoing ACI for symptomatic chondral defects. The mean follow-up was 54 months (range 12 – 108) and the mean defect size was 689 mm2 (range 350 – 1200). Nine patients had ACI-C and HTO, the remainder having MACI and HTO. Pre and postoperative assessment was carried out using the Visual Analogue Score (VAS), the Bentley Functional Rating Score and the Modified Cincinnati Rating System.

The Mean VAS score improved from 7.4 pre-operatively to 2.9 post-operatively (p< 0.0001). The Bentley Functional Rating Score improved from 2.9 to 1.8 (p< 0.0001) whilst the Modified Cincinnati Rating System improved from 35.2 pre-operatively to 68.7 post-operatively (p< 0.0001). There was no significant difference between ACI-C and MACI. Two patients developed a non union at a mean of 13 months and a further two patients had a failure of the chondrocyte graft at a mean of 22.5 months.

Combining high tibial osteotomy with autologous chondrocyte implantation is an effective method of decreasing pain and increasing function at mean of 54 months follow-up. Further follow-up is required to assess the long term outcomes of these combined procedures.

Introduction: The aim of this study is to investigate whether MoM implants result in more chromosome aberrations and increased blood metal ions post-operatively when compared to MoP implants.

Large head metal-on-metal articulating surfaces of the hip are being used in increasing numbers of patients for oncological purposes due to the increased stability and reduced dislocation rate. Recent studies have raised many concerns over possible genotoxicity of MoM implants.

Methods: This is a prospective study of patients who have undergone elective total hip replacement. Patients were randomised into two groups (MoP and MoM). Patients are reviewed pre-operatively (control group), at 3 months, 6 months, 1 year and 2 years post-operatively. On each occasion blood tests are taken to quantify metal ion levels (chromium, cobalt, titanium, nickel and vanadium) using HR-ICPMS and chromosome aberrations in T lymphocytes using 24 colour fluorescent in situ hybridisation (FISH).

Results: 24 patients had MoP prosthesis and 29 a MoM. Cobalt and chromium concentration increased during the first 6 months in both MoM and MoP groups, in the MoM group the chromium levels were twice that of MoP group and 12x that of the preoperative samples. There was no difference with the levels of titanium, nickel and vanadium. Chromosome aberrations occurred in both groups. At 6 months both the MoM and MoP groups showed increase frequency of aneuploidy aberrations with further increases after one year. Structural damage in the form of translocations occurred in the MoM group after one year, but not in the MoP group.

Discussion: Results of this study show that the levels of chromium and cobalt are significantly higher in the MoM group compared to the MoP group. This corresponds to increases in chromosome aberrations between the groups particularly in aneuploidy and translocations present in the MoM group at 1 year.

Purpose: To determine if Cobalt-Chrome (CoCr) femoral components of knee replacement components roughen significantly, and when significant roughening may start.

Methods:

Retrieval study:

14 knee replacement components were retrieved after revision procedures. The average surface roughness (Ra) of the articulating regions of each condyle was measured by surface profilometry and compared to Ra of non-articulating regions, which acted as controls on each implant.

In vitro testing:

Pin-on-plate testing of 6 paired CoCr pins and vacuum γ-irradiated UHMWPE discs was carried out under a force of 2.3kN at 1Hz to investigate how the articular Ra of CoCr pins varied with increasing number of cycles. Ra was measured at 0, 10, 100 and 1000 cycles using surface profilometry.

Results:

Retrieval analysis:

Average medial femoral condyle Ra was significantly greater than control Ra (p=0.040). Average lateral femoral condyle Ra was not significantly greater than control Ra (p=0.158). Significantly higher average Ra was seen on the medial condyles when compared with the lateral condyles (p < 0.05). 8/14 retrieved femoral components had ≥1 significantly roughened condyle (p< 0.05).

In vitro testing:

At 100 and 1000 cycles the Ra of the CoCr pins was significantly greater than Ra at 0 cycles (p< 0.05).

Conclusion: A large proportion of femoral components of knee replacement implants roughen significantly in vivo, a finding supported by our in vitro testing which indicates that roughening may begin very early on. This may have important implications for aseptic loosening of knee replacement components. However, the average Ra of those CoCr surfaces significantly (p< 0.05) roughened was within acceptable limits for orthopaedic implants (0.050μm).

Introduction: Metal-on-metal arthroplasties are being used for their increased durability and reduced requirement for revision. Previous data reports that metal-on-metal bearing surfaces release three times more cobolt and chromium ions than metal-on-polyethelene hip replacements. Data also suggests that these metal ions can cause DNA damage.

Method: A prospective study of patients (aged 60–80), meeting exclusion criteria were selected and randomised to metal-on-metal or metal-on-polyethylene articulation. Patients were reviewed preoperatively (control model) and at 3 months, 6 months and one year postoperatively. On each occasion blood tests were taken to quantify metal ion levels (chromium, cobalt, nickel, vanadium and titanium) and chromosome aberrations in T lymphocytes using 24 colour fluorescent in situ hybridization (FISH).

Results: The number of chromosome aberrations increased with time; in particular there was a statistically significant increase in aneuploidy after one year, there was also an increase in chromosome translocations. There was a similar increase in blood concentration of metal ions over this same time period which proved significant. Higher levels of metal ions were seen in the metal-on-metal group when compared with the metal-on-polyethylene.

Conclusion: This study has highlighted the effects of metal ions on chromosome replication in particular causing aneuploidy aberrations. This provides evidence of the short-term effects of metal-on-metal arthroplasty but further research needs to be undertaken to assess long-term risk and also the risk associated to other cell lines.

Introduction: Autologous Chondrocyte Implantation (ACI) is a treatment option for full-thickness chondral, or osteochondral injuries that are painful and debilitating. Goals of surgery and rehabilitation include replacement of damaged cartilage with hyaline or hyaline-like cartilage, leading eventually to improved level of function. Intermediate and long-term results are promising in terms of functional and clinical improvement.

Purpose: To explore the hypothesis that the quality of the repair tissue, formed following Autologous Chondrocyte Implantation (ACI), improves with time post-surgery.

Methods and Results: Two hundred and forty eight patients who underwent autologous chondrocyte implantation in our institution were studied after having had post implantation biopsies of the repair tissue. Mean timing of biopsy was 14.8 months (range 3–55). 59 biopsies gave hyaline tissue (24%), 67 mixed hyaline and fibrocartilage (27%), 113 biopsies were fibrocartilage only (46%) and 9 patients had a fibrous tissue biopsy result (9%). Due to NHS restraints and waiting list targets biopsies were actually performed at various time points post implantation allowing us to statistically correlate histological findings with the maturity of the repair tissue.

Our statistical analysis suggests that if time post implantation doubles then the likelihood of a favourable histological outcome increases significantly.

Conclusion: Autologous chondrocyte implantation forms a durable repair tissue that remodels and continues to improve in quality with time. It is recommended that for future research/study purposes 24 months is used as an optimal time to look at histology, since our data show that outcome is still improving until this point.

Introduction: Initial results for the management of osteochondral defects with both ACI-C and MACI have been encouraging, showing significant clinical improvement. This single-centre study set out to determine any significant difference in outcomes between ACI-C and MACI.

Aim: Reporting three year follow up of clinical and arthroscopic assessment of prospective analysis of ACI-C and MACI used in the management of symptomatic, full-thickness chondral and osteochondral defects in the knee.

Method: Following assessment arthroscopy and harvesting of chondrocytes for culture, patients were randomised into the ACI-C or MACI arm and underwent their respective procedures one month later. In ACI-C a covered technique is employed using a porcine-derived type I/III collagen membrane sutured in place; MACI requires cultured autologous chondrocytes to be seeded in a bi-layered type I/III collagen membrane which is glued into position. An arthroscopy was performed at 12 and 24 months postprocedure to assess graft coverage and biopsies taken to determine extent of hyaline, mixed and fibro-cartilage proliferation.

Results: 102 patients underwent either ACI-C (44) or MACI (58) with an average age of 33.6 (14–52). Mean Cincinnati knee rating scores recorded prior to assessment arthroscopy for ACI-C: 45.2 (10 – 94) and MACI: 45.5 (10 – 90) showed improvement at follow up with 63% of patients in the ACI-C group scoring good or excellent at three years, and 60% in the MACI group. ICRS arthroscopy scores were good or excellent in 91.4% of ACI-C and 76.1% of MACI patients at 24 months. Biopsies of the transplants at 24 months revealed proliferation of hyaline and mixed cartilage (hyaline and fibro-cartilage) in 48.6% of the ACI-C and 30.5% of the MACI patients.

Conclusion: Results to date suggest significant clinical and arthroscopic improvement following ACI-C and MACI, with evidence of proliferation of hyaline cartilage at the transplant site. Limited differences are noted between the outcomes of the two techniques.

Purpose: We attempted to identify whether patients with early evidence of osteoarthritis (OA) on their pre-operative radiographs were associated with poorer outcomes after Autologous Chondrocyte Implantation (ACI).

Methods: We retrospectively reviewed radiographs of 94 consecutive patients who underwent ACI and had already had their knee function assessed according to the Modified Cincinatti Score 2 years following surgery. Changes were graded according to The Kellgren and Lawrence (K& L) and the Stanmore grading system. Two independent observers analysed the films to assess the reproducibility and accuracy of these grading systems for assessment of OA in the knee.

Results: Patients were divided into 2 groups; Group A were patients with excellent/good outcome (52 patients), those with fair/poor outcome were Group B (42 patients).13 patients in Group A and 21 patients in Group B had radiographic evidence of OA (p< 0.025). In 34 patients who had OA (mean age 33.6) the increase in Cincinatti score following surgery was minimal (33.5 to 37.5). In 60 patients where there was no evidence of OA (mean age 33.7) the score increased from 40 to 53.4. The inter-observer variation was greater using K& L (Kappa=0.31) compared with the Stanmore grading systems (Kappa=0.72).

Conclusions: Patients with early radiographic evidence of OA are unlikely to gain maximum benefit from ACI. Furthermore, we recommend the use of Stanmore grading system for the assessment of OA as it is more reproducible than the K& L grading system.

Introduction: The use of custom made CAD-CAM femoral stems in primary Total Hip Replacement allows preservation of valuable bone stock in anatomically challenging femora whilst optimising biomechanics and improving function. The custom prosthesis design and manufacturing process is carried out with the aid of computed tomography (CT), a system of tomographic image processing, a Computer–Aided Design (CAD) system and a Computer–Aided Manufacturing (CAM) system.

Aim: To report seven year minimum follow up of a custom made and designed femoral component used in total hip replacement, focusing on clinical and radiographic evidence of failure.

Methods: Patients who had an uncemented total hip arthroplasty, by one of the two senior authors, with a CAD-CAM hip between February 1993 and February 2000 were retrospectively studied. An independent observer evaluated all patients radiologically using Engh’s criteria of osteointegration and clinically using Harris and Oxford Hip Scores.

Results: 85 patients (47 male, 38 female) (102hips) underwent THA for a variety of reasons between February 1993 and February 2000. Average age was 53.7 (25.4–91.5). Average follow up was 9.3 years (7–15). The aetiologies for THA were: Developmental Dysplasia of Hip (22 hips), Osteoarthritis (25), Slipped Upper Femoral Epiphysis (3), Skeletal Dysplasia (11), Trauma (9), Perthe’s Disease (6), Avascular Necrosis (14), Tumour (4) and other (8). At last follow up 4 hips had been revised: 2 for aseptic loosening, 1 for deep infection and 1 for excessive acetabular cup liner wear. 84 patients were evaluated (one deceased from unrelated causes). Average Harris Hip Score was 81 (range 53–96). Average Oxford Hip Score was 24 (range15–43). A full set of x-rays was available for 73 patients and when evaluated all were radiographically stable. Endosteal bone formation or spots welds were present on all 73 of the x-rays. Radiolucent lines at the bone-implant interface were present on 7/73 x-rays but did not correlate with clinical problems. There was no evidence of bone pedestal formation.

Conclusions: Clinical results are good to excellent with little radiographic evidence of failure. CAD-CAM hips can be safely and reliably used for a variety of aetiologies with predictable result at least up to seven years postoperatively.

Orthopaedic surgeons vary in their attitude towards resurfacing of the patella in total knee arthroplasty. Few studies are available to assess outcome and patient preference. We evaluated post-operative anterior knee pain and knee preference in patients with bilateral knee replacements and unilateral patellar resurfacing.

We reviewed 30 patients who had undergone bilateral knee replacement with patellar resurfacing on only one side. Follow-up was from five to 12 years and the patients were assessed using the Knee Society rating, an anterior knee pain rating and a satisfaction score. Patients were also asked specifically if they had a preference for either knee. Assessment was performed without knowing which patella had been resurfaced.

Fourteen patients (47%) favoured the resurfaced knee, six (20%) the un-resurfaced knee and 10 (33%) had no particular preference. The overall prevalence of anterior knee pain was 50% in the un-resurfaced cases (six mild, six moderate, three severe) and 20% in the resurfaced knees (four mild, two moderate). No significant difference was found between knee scores. Three un-resurfaced patellae have been secondarily resurfaced.

This study shows a significant preference for the resurfaced side (p< 0.01), with a higher prevalence of anterior knee pain in non-resurfaced patellae (p< 0.05).

Our aim was to review the short-term clinical results of a single-institution cohort undergoing opening wedge high tibial osteotomy (HTO).

We undertook a prospective clinical and radiographic review of our cohort of patients who had undergone opening wedge HTO for varus malalignment. The Cincinnati scoring system was used for objective assessment. Pre- and post-operative radiographs were evaluated and Blackburne-Peel (BP) and Insall-Salvati (IS) ratios recorded, as well as integrity of the lateral hinge.

We reviewed 55 knees (51 patients: 34 men and 17 women; mean age, 44.2years; range 34–58years) followed up for a minimum 12 months (range, 12–62months). All patients had relief of pain, but six met our criteria of failed treatment where either revision fixation was required or proceeded to total knee arthroplasty for persisting symptoms. Cincinnati scores were 94.5% excellent (52/55) and 5.5% good (3/55) at 1 year, whilst at last follow-up they were 87.2% excellent (48/55), 9.1% good (5/55) and 3.6% fair (2/55). There was a significant improvement in mean American Knee Society score at 1 year and maintained at last follow-up (p< 0.05). Radiographically the lateral hinge was noted to be breached in 9.1% (5/55), but no incidence of non-union was identified. There was no significant change in IS index, however BP index diminished by a mean 15.3% (range, 7.4–28.2%). Medial opening wedge tibial osteotomy results in patellar infera, but successful clinical and functional outcomes have been demonstrated. The fact ther e is inconsistency between the two indices assessing patellar height ratio we believe reflects the inherent variability in the techniques employed. Distalisation of the tibial tubercle will mean the IS ratio remains unaffected, whilst the BP index more accurately demonstrates the lowering of patella relative to the joint line. However there may be other factors which are not immediately appreciated, such as changes in the tibial inclination or antero-posterior translation.

Introduction: We report our experience with use of the SMILES prosthesis in primary knee arthroplasty.

Methods: The Stanmore Modular Individualised Lower Extremity System (SMILES prosthesis) has been shown to be effective in complex revision knee surgery. It incorporates a rotating hinge platform knee joint and can overcome the major problems of bone loss and ligamentous laxity.

38 patients (41 knees) who received a primary SMILES knee prosthesis by one of the senior authors between 1990 and 2006 were retrospectively studied. Knee function was assessed pre and post-operatively using the Oxford knee score (0–48 scoring system) and the Knee Society Score. Patients receiving surgery for tumours were excluded. The main indications for primary SMILES were bone loss and ligamentous laxity.

Results: The minimum follow-up was 18 months with a mean of 5 years (1–17). The mean age of the patients was 57.7 years (23–86); 15 of the patients were male. The indications for surgery were trauma (12), osteoarthritis with deficient medial collateral ligament (8), polio (7), rheumatoid arthritis (5), epiphyseal dysplasia (4), achondroplasia (2), avascular necrosis (1), osteogenesis imperfecta (1) and ankylosing spondylitis (1).

2 patients died and 5 were lost to follow-up. 2 patients required revision surgery (one for infection and one for re-bushing). Post-operative complications included peroneal nerve palsy (1) and DVT (1). The mean Oxford knee score improved from 9 pre-op to 44 post-op, and the mean knee society score improved from 24 pre-op to 71 post-op. The average range of motion was 57 degrees pre-op and 88 degrees post-op.

Conclusion: We conclude that the SMILES prosthesis offers significant improvement in clinician and patient assessed outcome scores in complex primary knee arthroplasty. The cost compares favourably with other designs and its use is well established.

Our aim was to review the short-term clinical results of a single-institution cohort undergoing opening wedge high tibial osteotomy (HTO).

We undertook a prospective clinical and radiographic review of our cohort of patients who had undergone opening wedge HTO for varus malalignment. The Cincinnati scoring system was used for objective assessment. Pre- and post-operative radiographs were evaluated and Blackburne-Peel (BP) and Insall-Salvati (IS) ratios recorded, as well as integrity of the lateral hinge.

We reviewed 55 knees (51 patients: 34 men and 17 women; mean age, 44.2years; range 34–58years) followed up for a minimum 12 months (range, 12–62months). All patients had relief of pain, but six met our criteria of failed treatment where either revision fixation was required or proceeded to total knee arthroplasty for persisting symptoms. Cincinnati scores were 94.5% excellent (52/55) and 5.5% good (3/55) at 1 year, whilst at last follow-up they were 87.2% excellent (48/55), 9.1% good (5/55) and 3.6% fair (2/55). There was a significant improvement in mean American Knee Society score at 1 year and maintained at last follow-up (p< 0.05). Radiographically the lateral hinge was noted to be breached in 9.1% (5/55), but no incidence of non-union was identified. There was no significant change in IS index, however BP index diminished by a mean 15.3% (range, 7.4–28.2%). Opening wedge HTO provides a means of relieving stress distribution through the medial tibiofemoral compartment and results in effective relief of symptoms with improvement in functional outcome and quality of life.

Aim: To review the short-term clinical results of a single-institution cohort undergoing opening wedge high tibial osteotomy (HTO).

Method: We undertook a prospective clinical and radiographic review of our cohort of patients who had undergone opening wedge HTO for varus malalignment. The Cincinnati scoring system was used for objective assessment. Pre- and post-operative radiographs were evaluated and Blackburne-Peel (BP) and Insall-Salvati (IS) ratios recorded, as well as integrity of the lateral hinge.

Results: we reviewed 55 knees (51 patients: 34 men and 17 women; mean age, 44.2 years; range 34–58 years) followed up for a minimum 12 months (range, 12–62 months). All patients had relief of pain, but six met our criteria of failed treatment where either revision fixation was required or proceeded to total knee arthroplasty for persisting symptoms. Cincinnati scores were 94.5% excellent (52/55) and 5.5% good (3/55) at 1 year, whilst at last follow-up they were 87.2% excellent (48/55), 9.1% good (5/55) and 3.6% fair (2/55). There was a significant improvement in mean American Knee Society score at 1 year and maintained at last follow-up (p< 0.05). Radiographically the lateral hinge was noted to be breached in 9.1% (5/55), but no incidence of non-union was identified. There was no significant change in IS index, however BP index diminished by a mean 15.3% (range, 7.4–28.2%).

Discussion: Medial opening wedge tibial osteotomy results in patellar infera, but successful clinical and functional outcomes have been demonstrated. The fact there is inconsistency between the two indices assessing patellar height ratio we believe reflects the inherent variability in the techniques employed. Distalisation of the tibial tubercle will mean the IS ratio remains unaffected, whilst the BP index more accurately demonstrates the lowering of patella relative to the joint line. However there may be other factors which are not immediately appreciated, such as changes in the tibial inclination or antero-posterior translation.

Autologous chondrocyte implantation is an option in the treatment of full-thickness chondral or osteochondral injuries which are symptomatic. The goal of surgery and rehabilitation is the replacement of damaged cartilage with hyaline or hyaline-like cartilage, producing improved levels of function and preventing early osteoarthritis. The intermediate results have been promising in terms of functional and clinical improvement.

Our aim was to explore the hypothesis that the histological quality of the repair tissue formed after autologous chondrocyte implantation improved with increasing time after implantation.

In all, 248 patients who had undergone autologous chondrocyte implantation had biopsies taken of the repair tissue which then underwent histological grading. Statistical analysis suggested that with doubling of the time after implantation the likelihood of a favourable histological outcome was increased by more than fourfold (p < 0.001).

Introduction: Blood management in the perioperative period of the total joint arthroplasty procedure has evolved over the last 3 decades. We performed two separate studies:

1) observational study to analyse surgeon’s and anaesthetist’s attitude to transfusion

Method: 500 orthopaedic surgeons and 336 anaesthetists were surveyed to assess current UK attitudes towards transfusion practice following arthroplasty.

200 patients (88 THR, 99 TKR, 13 hip resurfacing) were evaluated. Blood Hb, hand grip strength and vigour scores using fatigue questionnaire were estimated both preoperatively and at 3 days following surgery. POMS and the required duration of in-patient physiotherapy were also noted. The protocol for blood transfusion was for those with Hb less than 8 g/dL and/or post-operative symptoms attributable to anaemia.

Results: In an uncomplicated patient following total hip arthroplasty, 53.2% of surgeons and 63.1% of anaesthetists would transfuse at or below Hb of 8g/dL. Mean transfusion threshold in surgeons was 8.3g/dL compared to 7.9g/dL for anaesthetists (p< 0.01). 97% of surgeons transfused two or more units compared to 78% anaesthetists (p< 0.01). This threshold Hb increased if patient was symptomatic (surgeons 9.3g/dL, anaesthetists 8.8g/dL, p< 0.05), or if known to have pre-existing ischaemic heart disease (surgeons 9.0g/dL, anaesthetists 9.2g/dL, p< 0.05).

A greater fall in postoperative Hb correlated significantly with a greater reduction in post-operative vigour score (p=0.02). Also a greater fall in vigour score was found to correlate significantly with the duration of in-patient physiotherapy (p< 0.001). A reduction in Hb of > 4g/dL from the pre-operative Hb predicted a significantly higher reduction in vigour score (p=0.03). A weak correlation was seen between a fall in Hb and POMS (p=0.09).

A higher pre-operative Hb did not reduce the required duration of in-patient physiotherapy (p=0.72). There was no correlation between post-operative Hb and POMS (p=0.21) or duration of in-patient physiotherapy (p=0.20).

A higher pre-operative grip strength predicted an early date of discharge by the physiotherapists (p=0.02).

Conclusion: Haemoglobin level below 9g/dL is the most common ‘trigger’ for blood transfusion. Surgeons tend to be more aggressive in their attitude to transfusion. A fall in Hb of more than 4 g/dL has a detrimental effect on post-operative rehabilitation. Pre-operative grip strength measurements are valuable in predicting the rehabilitation potential of patients undergoing lower limb arthroplasty.

Introduction: Smoking is associated with impaired wound healing, delayed bony union following fractures and an adverse effect on the immune system. Furthermore, smoking is an important risk factor for the development pulmonary complications following major surgical procedures, as well as wound complications. We determined whether smoking had a deleterious effect on outcome after autologous chondrocyte implantation (ACI) in the treatment of ostechondral defects of the knee.

Methods: We identified 103 (54 females and 49 males) patients with a mean age of 34.2 (range 18 to 49) who had undergone ACI between January 2001 and August 2004 who also had their smoking status recorded. The patients were divided into 3 groups according to their smoking status. The Visual Analogue Score, Bentley Functional Rating Score and Modified Cincinatti Scores were used to assess function pre-operatively, 6 months and then yearly thereafter.

Results: Group 1 consisted of 31 smokers (mean pack years of 13.4), group 2 consisted of 63 non-smokers and group 3 contained 9 ex-smokers. In Group 1, the Modified Cincinatti Score pre-operatively, 6 months, 1 year and 2 years following surgery were 34.1, 42.6, 43.5 and 46.7 respectively. In group 2 the scores were 47.4, 59.6, 59.1, 65.3, and in group 3 the scores were 39.8, 50, 53.3, 51.8. At the 1 year check arthroscopy, the graft failure rate in group 1 was 12% and biopsies revealed mixed hyaline and fibrocartilage in only 25% (there were no patients with hyaline cartilage). There were no graft failures in group 2 and 43.8% of the biopsies performed were either hyaline (12.5%) or mixed hyaline and fibrocartilage (31.3%). The wound complication rate was 24% in group 1 and 8% in group 2.

Conclusions: The results of this study suggest that people who smoke have a worse functional outcome and a higher complication rate following chondrocyte implantation. This association has not been previously described and should be included in the pre-operative counselling of patients undergoing the procedure.

Introduction: Several studies have implicated excessive weight as a negative predictor of success of total knee arthroplasty. In addition, obese patients are known to have increased risk of wound complications after orthopaedic and general surgery. The purpose of this study was to compare the clinical and functional outcomes of autologous chondrocyte implantation for treatment of osteochondral defects of the knee performed in obese patients with those performed in non-obese patients.

Methods: We analysed the data on all our patients that have been followed up for a minimum of 2 years and had their height and weight recorded initially in our database. Functional assessment consisted of Bentley Functional Rating Score, Visual Analogue Score, and the Modified Cincinatti Scores (collected prospectively at 6 months, 1 year, 2 years and 3 years following surgery). Patients were placed into 3 groups according to their body mass index (BMI). Group A consisted of patients with BMI of 20 to 24.9, group B patients with BMI of 25 to 29.9 and Group C are patients with BMI of 30 to 39.9.

Results: There were 80 patients (41 males and 39 females) with a mean age of 35.4 (range 18 to 49). The mean BMI for the entire group was 26.6. The pre-operative, 6 month, 1 year, 2 year, and 3 year Modified Cincinatti Score in Group A (32 patients) was 54.4, 80.3, 82.7, 74.7 and 72.6. Similarly in Group B, the scores were 53, 41, 54, 56, 49.5 and in Group C the scores were 36.3, 36.3, 49.6, 36, and 35.7. The wound infection rate in Group A was 6.25%, in Group B was 17.6% and Group C was 14.3%.

Conclusions: Initial results from this study suggest that BMI is an important predictor of outcome after chondrocyte implantation. The group of patients that would gain most benefit from ACI are patients that are not overweight (defined by BMI in the range of 20 to 24.9). Further work is being carried out to support the hypothesis that surgeons should strongly consider not operating on patients unless the BMI is less than 25.

Introduction: ACI is used widely as a treatment for symptomatic chondral and osteochondral defects of the knee. Variations of the original periosteum-cover technique include the use of porcine-derived type I/type III collagen as a cover (ACI-C) and matrix-induced autologous chondrocyte implantation (MACI) using a collagen bilayer seeded with chondrocytes. We report the minimum 2 year follow-up results of 192 patients randomised to autologous chondrocyte implantation (ACI) using porcine-derived collagen membrane as a cover (ACI-C) and matrix-induced autlogous chondrocyte implantation (MACI) for the treatment of osteochondral decfects of the knee.

Methods: 192 patients (mean age 34.2) were randomised to have either ACI (86 patients) or MACI (106 patients). 1 year following surgery patients underwent check arthroscopy (with or without biopsy) to assess the graft. Functional assessment was performed yearly by using the modified Cincinatti knee score, the Bentley functional rating score and the visual analogue score.

Results: 24 patients were excluded from the study as they underwent additional procedures (e.g. high tibial osteotomy). In the ACI group the modified Cincinatti score increased from 42.5 pre-operatively to 56.7, 54.1, and 60.4 at 1 year, 2 years and 3 years respectively. In the MACI group the Cincinatti scores increased from 46.0 pre-operatively to 59.9, 58.9, and 58.4. Arthroscopic assessment showed a good to excellent International Cartilage Repair Society score in 90.7% of ACI-C grafts and 68.4% of MACI grafts. Hyaline-like cartilage or hyaline-like with fibrocartilage was found in biopsies of 51.9% of ACI-C grafts and 25.9% of MACI grafts.

Conclusions: ACI grafts are more likely to produce hyaline-like or mixed hyaline-like cartilage and fibro-cartilage with better ICRS grades than MACI grafts. However, this does not translate to better a clinical functional outcome. More importantly, ACI and MACI had similar results that were maintained at 3 years.

We aimed to determine whether proximal femoral bone remodelling, as measured by DEXA scan for each Gruen Zone, differed for 3 different femoral stem designs. These were:

Group 1 – Triple taper polished (C-stem J& J DePuy)

Ethical Committee approval was obtained and all patients gave informed consent. All operations were performed by 3 surgeons using a standard lateral approach, third generation cementing technique and a standard post-operative regime.

Seventy-five patients were randomised prospectively using a stratified randomisation programme for known risk factors in bone density. The randomisation was stratified by age, sex, Charnley Group (A or B), BMI and femoral neck bone mineral density. There were 25 patients in each Group, 5 patients did not have complete data sets and were therefore withdrawn from evaluation.

The Groups were similar with regard to age, sex, BMI, BMD and Charnley Group. Patients were followed up at 3, 6, 12 and 24 months by Nurse Practitioners for clinical and radiological evaluation and DEXA scan at each time of follow-up. There were no catastrophic failures of sepsis or dislocation. All patients functioned well at 24 months by Harris Hip Score.

The bone remodelling pattern will be described for each stem design. Findings are summarised thus. In the lateral Gruen Zones the triple taper and collared stem design faired better and both behaved differently to the double taper design. In Gruen Zone 7, all stems demonstrated reduced bone density as compared to pre-operative scans but this was less with the triple taper design.

Aims: To compare the clinical and functional outcomes of autologous chondrocyte implantation for treatment of osteochondral defects of the knee performed in overweight, obese and patients of ‘ideal weight’as defined by their BMI.

Methods: We analysed the data on all our patients that have been followed up for a minimum of 2 years and had their height and weight recorded initially in our database. Functional assessment consisted of the Modified Cincinatti Scores (collected prospectively at 6 months, 1 year, 2 years and 3 years following surgery). Patients were placed into 3 groups according to their body mass index (BMI). Group A consisted of patients with BMI of 20 to 24.9, group B patients with BMI of 25 to 29.9 and Group C are patients with BMI of 30 to 39.9.

Results: There were 80 patients (41 males and 39 females) with a mean age of 35.4 (range 18 to 49). The mean BMI for the entire group was 26.6. The pre-operative, 6 month, 1 year, 2 year, and 3 year Modified Cin-cinatti Score in Group A (32 patients) was 54.4, 80.3, 82.7, 74.7 and 72.6. Similarly in Group B, the scores were 53, 41, 54, 56, 49.5 and in Group C the scores were 36.3, 36.3, 49.6, 36, and 35.7. The wound infection rate in Group A was 6.25%, in Group B was17.6% and Group C was 14.3%.

Conclusions: Initial results from this study suggest that BMI is an important predictor of outcome after chon-drocyte implantation. The group of patients that would gain most benefit from ACI are patients that are not overweight (defined by BMI in the range of 20 to 24.9). Further work is being carried out to support the hypothesis that surgeons should strongly consider not operating on patients unless the BMI is less than 25.