Matrix metalloproteinase-13 is fully activated by neutrophil elastase and inactivates its serpin inhibitor, alpha-1 antitrypsin: Implications for osteoarthritis.

Matrix metalloproteinase-13 (MMP-13) is a uniquely important collagenase that promotes the irreversible destruction of cartilage collagen in osteoarthritis (OA). Collagenase activation is a key control point for cartilage breakdown to occur, yet our understanding of the proteinases involved in this process is limited. Neutrophil elastase (NE) is a well-described proteoglycan-degrading enzyme which is historically associated with inflammatory arthritis, but more recent evidence suggests a potential role in OA. In this study, we investigated the effect of neutrophil elastase on OA cartilage collagen destruction and collagenase activation. Neutrophil elastase induced significant collagen destruction from human OA cartilage ex vivo, in an MMP-dependent manner. In vitro, neutrophil elastase directly and robustly activated pro-MMP-13, and N-terminal sequencing identified cleavage close to the cysteine switch at 72 MKKPR, ultimately resulting in the fully active form with the neo-N terminus of 85 YNVFP. Mole-per-mole, activation was more potent than by MMP-3, a classical collagenase activator. Elastase was detectable in human OA synovial fluid and OA synovia which displayed histologically graded evidence of synovitis. Bioinformatic analyses demonstrated that, compared with other tissues, control cartilage exhibited remarkably high transcript levels of the major elastase inhibitor, (AAT) alpha-1 antitrypsin (gene name SERPINA1), but these were reduced in OA. AAT was located predominantly in superficial cartilage zones, and staining enhanced in regions of cartilage damage. Finally, active MMP-13 specifically inactivated AAT by removal of the serine proteinase cleavage/inhibition site. Taken together, this study identifies elastase as a novel activator of pro-MMP-13 that has relevance for cartilage collagen destruction in OA patients with synovitis.

Displaced mid-shaft clavicular fractures: state of the art for athletes and young active people.

INTRODUCTION: Fractures ofthe clavicle are frequent injuries (between 4 and 10% of adult fractures) and mid-shaft diaphyseal fractures represent more than 80% of clavicle fractures. In a recent study from the USA in 2019, an incidence of 22.4 fractures per year per 100,000 people was reported. Multiple injury mechanisms are recognised, with sport accounting for 50 to 85% of these injuries. There is little or no consensus as to the optimal treatment but in recent years multiple studies have suggested operative management should be favoured in athletes and young active patients. OBJECTIVES: These are (1) to present the anatomy and the anatomical-pathology of the fractures of the clavicle as well as the mechanisms of injury, (2), (3) to describe non-operative and operative treatment methods, (4) to review the literature around different treatment modalities and (5) to attempt to describe the best treatment for athletes. METHODS: To collect and analyse the most recent articles of the literature regarding the management of displaced mid-shaft fractures of the clavicle for athletes and young active people. RESULTS: Looking at studies of the general population, the results tend to favour surgical treatment with a smaller incidence of non-union and faster return to function. These results are mirrored in the athlete population where several studies have shown excellent anatomic restoration and functional recovery after plate fixation. CONCLUSION: Based on this analysis, with the exception of patients who refuse operative management after an informed discussion, the treatment of choice in displaced clavicle fractures in athletes seems to be operative treatment with a plate and screws. However, prospective randomised studies comparing non-surgical treatment and plate osteosynthesis are missing and it is not possible to state that the latter is the best treatment.

Influence of the post-operative axis on the clinical results of total knee replacement for severe varus deformities: does a slight residual varus improve the results?

PURPOSE: Some recent articles have suggested that in the case of large varus deformity, it may be advantageous to leave some residual post-operative varus as a means of improving functional outcome. The objective of this study is to compare the results of total knee replacement (TKR) performed for significant varus deformity (HKA < 170°) where there is a residual post-operative varus (HKA < 180°) to the results of TKR for significant varus deformity with either neutral post-operative (HKA = 180°) or mild valgus post-operative alignment (HKA > 180°). METHODS: This series was made up of 208 knees. The mean pre-operative HKA angle was 166 ± 3° (154-169°), of which 150 were followed up for a mean 8.5 years (58 lost to follow-up). Based on post-operative radiographs, two groups were formed: group 1 (88 knees) in which post-operative alignment was 177.8 ± 1° (175-179°) and group 2 (62 knees) in which post-operative alignment was 181 ± 1° (180-184°). RESULTS: The mean international knee society (IKS) score for group 1 was 178.8 ± 22 points (113-200) and 181.7 ± 22 points (95-200) for group 2. Oxford knee score was 20.4 ± 9 points (12-45) in group 1 and 19.2 ± 9 (12-50) in group 2. The results were slightly better in group 2 (in slight valgus) but this difference was not statistically significant (p = 0.44 and 0.4). CONCLUSION: The results of knee replacement performed for severe varus deformity are not adversely affected by post-operative valgus alignment. There is in fact a trend towards superior results for neutral or valgus alignment than slight residual varus, but this difference was not statistically significant.

Antibiotic resistance profiles of deep surgical site infections in hip hemiarthroplasty; comparing low dose single antibiotic versus high dose dual antibiotic impregnated cement.

Objectives: The incidence of fractured neck of femur (FNOF) is increasing yearly. Many of these patients undergo hip hemiarthroplasty. High dose dual-antibiotic cement (HDDAC) has been shown to reduce rates of deep surgical site infection (SSI) when compared to the current standard low dose single-antibiotic cement (LDSAC) in a quasi-randomised controlled trial. Some concerns exist regarding the use of HDDAC and the development of antibiotic resistance. We reviewed cases of infection in LDSAC and HDDAC bone cement with regard to causative organism and resistance profile. Methods: A retrospective analysis was undertaken of all hemiarthroplasties within our trust from April 2008 to December 2014. We identified all patients in this time period who acquired a deep SSI. The infecting organisms and susceptibility patterns were collated for each cement. Results: We identified 1941 hemiarthroplasties. There were 38 deep surgical site infections representing an infection rate of 3.4% in LDSAC patients and 1.2% in HDDAC patients. The majority of infections were polymicrobial. Staphylococcus epidermidis was the most commonly isolated organism. It accounted for a larger proportion of HDDAC than LDSAC infections (p<0.05). Infection with Corynebacterium species and S. aureus, including MRSA, was eradicated completely with the use of HDDAC. There was no significant change in the proportion of Gram negative and Gram positive infections between the two cements. In Gram positive organisms, there was no significant change in resistance to most antibiotics. Although fewer resistant infections overall, there were significant increases in the proportion of resistance to ciprofloxacin and clindamycin with HDDAC. We observed no resistance to daptomycin or linezolid in either cement and levels of resistance remained low to rifampicin and teicoplanin. In Gram negative organisms, no significant change in resistance was observed. Conclusions: We observed a significantly lower infection rate with the use of HDDAC compared to LDSAC. Such was this reduced infection rate that there was a trend to a lower rate of resistance with the use of HDDAC. However, there were increases in the proportion of resistant cases, most notably to clindamycin and ciprofloxacin in Gram positive organisms, possibly reflecting the higher number of S. epidermidis in the HDDAC group. Whilst the differences in our study were not found to be statistically significant, it is reassuring for teams using HDDAC to prevent SSI in hip hemiarthroplasty.

Results of the Latarjet coracoid bone block procedure performed by mini invasive approach.

INTRODUCTION: The coracoid block technique described by Latarjet was modified by Patte and Walch in order to increase the glenoid surface. Saragaglia further modified this technique and described a minimally invasive approach which allows faster post-operative recovery. The aim of this study was to evaluate the medium-term functional and radiological results of this technique. METHODS: This is a single surgeon cohort of 40 shoulders in 38 patients (32 men, 6 women) with an average age of 34.5 years operated on between January and December 2014. The skin incision was 3 to 6 cm long allowing the bony block to be passed under the subscapularis tendon without sectioning it and to be placed in lying position. The bone block was fixed with a 6.5 cancellous screw or a 7.0 cannulated screw. RESULTS: At an average follow-up of 48 months, there were no recurrent dislocations. The average WOSI score was 42, the average Constant score was 95 corrected to 97% and the average SSV was 97. Visual analogue scores were 0 at rest and 0.6 with activity. The bone block healed in 92.5% of cases. It was flush with the edge of the glenoid in 84% of cases, lateralised in 10% and medialised in 6% of cases. Mean internal rotation power was 12 kg in the operated shoulder compared with 9 kg in the non-operated shoulder. CONCLUSION: The treatment of recurrent anterior shoulder instability by mini invasive Latarjet gives excellent medium-term functional results. The rate of recurrent dislocation in this series was zero and internal rotation power was well preserved. This is an excellent alternative to arthroscopic procedures which are yet to demonstrate their superiority over open surgery.

Results with nine years mean follow up on one hundred and three KAPS® uni knee arthroplasties: eighty six medial and seventeen lateral.

PURPOSE: The purpose of this study was to present the results of the KAPS® uni knee arthroplasty system, both mobile and fixed bearing with reference to function, alignment and complications in 103 implants with a mean follow-up of nine years. METHODS: This was a retrospective study of 103 unicompartimental knee arthroplasties in 89 patients operated on between March 2005 and March 2010. The population was composed of 50 males and 39 females, with a mean age of 70.5 ± 7.5 years (41 - 90). Eighty-seven patients had a genu varum deformity (84.5%), one of whom had an osteoid osteoma of the lateral tibial plateau and 16 patients had a genu valgum (15.5%). Eighty-six medial prostheses were implanted (82 mobile bearings and 4 fixed bearings) and 17 lateral prostheses (all fixed bearings) including the osteoid osteoma. RESULTS: At a mean follow-up of 107.5 months (73-138), 72 knees (58 patients) were reviewed (70%). The mean IKS score was of 173 ± 31 points (58 - 200). The mean Oxford knee score was 21 ± 8 points (12 - 50). The cumulated survival rate at a follow up of 132 months was 98.2%. CONCLUSION: The KAPS® unicompartmental knee arthroplasty gives efficacious and safe outcomes in the majority of cases at a mean follow-up of nine years. The availability of both fixed and mobile bearings with the same instrumentation, allowing to choose the right implant intra-operatively, is a great advantage in order to avoid the occurrence of some complications, specific to mobile bearing prostheses (dislocation and over-correction).

Ganglion cysts of the proximal tibiofibular articulation: the role of arthrodesis and combined partial fibula excision.

PURPOSE: Cysts of the proximal tibiofibular articulation are rare and their optimal treatment remains unclear. The objective of this study was to evaluate the results and complications of the treatment of synovial ganglion cysts of the proximal tibiofibular articulation by simple excision or by excision and fusion of the proximal tibiofibular joint with a limited fibula excision. METHODS: Between January 2005 and December 2016, seven male patients with an average age of 46 years were treated for a ganglion cyst of the proximal tibiofibular articulation. Nine procedures were performed in total. Four patients underwent primary cyst excision, two underwent revision cyst excision and three underwent revision cyst excision with arthrodesis of the proximal tibiofibular joint and partial excision of the fibula (two patients underwent two procedures). RESULTS: Average follow-up was 79 months. The recurrence rate was 25% for simple cyst excision, 100% for revision cyst excision and 0% for cyst excision with arthrodesis. Average kitaoka score was 98 for simple cyst excision and 100 for cyst excision with arthrodesis (P = 0.34); resting visual analogue scores (VAS) were zero in both groups. With activity VAS was 0 for simple cyst excision and 1.6 in the arthrodesis group (P = 0.33). Two of the three arthrodesis patients went on to successful fusion. The third patient has an asymptomatic pseudarthrosis. CONCLUSION: Simple primary cyst excision has a high failure rate at 25%. Revision cyst excision without fusion failed in all cases. We therefore recommend arthrodesis with limited fibula excision.

Computer-assisted total knee replacement after medial opening wedge high tibial osteotomy: medium-term results in a series of ninety cases.

PURPOSE: The aim of this study was to evaluate the medium-term results of total knee replacements (TKRs) after medial opening wedge valgising tibial osteotomy to those of primary TKR (TKR1). The hypothesis being that there would be no difference in results between these groups. METHODS: Series 1 was made up of 45 TKRs after medial opening wedge high tibial osteotomy (MHTO)-30 men and ten women at an average age of 69 ± seven years (54-82). This was compared to a second series of TKR1s-30 men and ten women at an average age of 69 ± seven years (55-78). The average IKS scores were 91 ± 22.5 points (42-129) and 86 ± 18 points (38-116) in the two groups respectively. The average pre-operative HKA angle was 179 ± 5° (169-193°) in group 1, and 173 ± 7.5° (161-193°) in group 2. Tibial mechanical axes were 90.5 ± 4° (of which 24 knees had a valgus angle) and 85.05 ± 3.5° (79-93°) in the two groups respectively. RESULTS: All patients were reviewed at an average follow-up of 47 ± 24.5 months for series 1 and 185 ± 8.5 months for series 2. The average IKS score was 184 ± 6 for series 1 (172-200) and 185 ± 8.5 (163-200) for series 2 (p = 0.872). Thirty-seven patients in series 1 and 38 patients in series 2 were either extremely satisfied or satisfied with the intervention. The average post-operative HKA angle was 180.5 ± 2.5° and 181 ± 2° (p = 0.122) and the average tibial mechanical axis was 89 ± 1.5° against 90 ± 1° (p = 0.001). The results of the 24 knees with a valgus tibial mechanical axis were statistically no different. CONCLUSIONS: TKRs post medial opening wedge high tibial osteotomy have identical results to primary TKRs even in knees with a valgus tibial mechanical axis.

Computer navigation for revision of unicompartmental knee replacements to total knee replacements: the results of a case-control study of forty six knees comparing computer navigated and conventional surgery.

PURPOSE: The revision of unicompartmental knee replacements (UKRs) to total knee replacements (TKRs) using computer navigation is a little-known technique. The principal objective of this study was to analyse the radiological position of implants in revision of UKR to TKR comparing the results of surgery aided by computer navigation (CAS) with conventional surgery (CS). Our hypothesis was that computer navigation would improve the position of the implants. METHODS: This is a retrospective single surgeon series. Forty-six patients (46 knees) with an average age 73 ± eight years (53-93) between January 1995 and December 2014 were included. The two groups were made up of 23 patients each and are comparable in terms of age, sex, side of surgery, age of the UKR, cause of failure and HKA angle before surgery. All patients were reviewed by two independent observers. RESULTS: In the CAS group, the average hip-knee-ankle (HKA) angle was 179.2 ± 2.2° (175-184°). The average medial tibial mechanical angle (TMA) was 88.4 ± 1.6° (84-90°) and the medial femoral mechanical angle (FMA) was 91 ± 2° (87- 94°). The tibial slope was 88.7 ± 1.1° (87-90°). In the CS group, the average HKA angle was 179.9 ± 1.9° (175-183°), the TMA was on average 89.1 ± 1.3° (87-93°) and the FMA was 90.6 ± 1.5° (87-93°). The tibial slope was 87.8 ± 4.9° (85-95°). There was no statistically significant difference between the two groups on any of the radiological parameters studied. CONCLUSIONS: Our radiological target of a post-operative HKA angle of 180 ± 3° was obtained in 87.5% of cases in the CS group and 92.4% of cases in the CAS group. This slight difference in favour of the computer-assisted group was not statistically significant, and we cannot therefore confirm our initial hypothesis, at least in the hands of an experienced surgeon. However, the quality of the results in the CAS group suggest that this technique could provide precious assistance to less experienced surgeons performing this surgery.

The effect of introducing a Trauma Network on patient flow, hospital finances and trainee operating.

In April 2012 the National Health Service in England introduced the Trauma Network system with the aim of improving the quality of trauma care. In this study we wished to determine how the introduction of the Trauma network has affected patient flow, hospital finances and orthopaedic trauma training across our region. The overall pattern of trauma distribution was not greatly affected, reflecting the relative rarity of major trauma in the UK. A small decrease in the total number of operations performed by trainees was noted in our region. Trainees at units designated as Major Trauma Centres gained slightly more operative experience in trauma procedures overall, and specifically in those associated with high energy, such as long bone nail insertion and external fixation procedures. However, there have been no significant changes in this pattern since the introduction of the Trauma Networks. Falling operative numbers presents a challenge for delivering high quality training within a surgical training programme, and each case should be seen as a vital educational opportunity. Best practice tariff targets for trauma were delivered for 99% of cases at our MTCs. Future audit and review to analyse the evolving role of the MTCs is desirable.

The risk of cardiorespiratory deaths persists beyond 30 days after proximal femoral fracture surgery.

INTRODUCTION: 30-day mortality is routinely used to assess proximal femoral fracture care, though patients might remain at risk for poor outcome for longer. This work has examined the survivorship out to one year of a consecutive series of patients admitted for proximal femoral fracture to a single institution. We wished to quantify the temporal impact of fracture upon mortality, and also the influence of patient age, gender, surgical delay and length of stay on mortality from both cardiorespiratory and non-cardiorespiratory causes. PATIENTS AND METHODS: Data were analysed for 561 consecutive patients with 565 fragility type proximal femoral fractures treated surgically at our trauma unit. Dates and causes of death were obtained from death certificates and also linked to data from the Office of National Statistics. Mortality rates and causes were collated for two time periods: day 0-30, and day 31-365. RESULTS: Cumulative incidence analysis showed that mortality due to cardiorespiratory causes (pneumonia, myocardial infarction, cardiac failure) rose steeply to around 100 days after surgery and then flattened reaching approximately 12% by 1 year. Mortality from non-cardiorespiratory causes (kidney failure, stroke, sepsis etc.) was more progressive, but with a rate half of that of cardiorespiratory causes. Progressive modelling of mortality risks revealed that cardiorespiratory deaths were associated with advancing age and male gender (p<0.001 for both), but the effect of age declined after 100 days. Non-cardiorespiratory deaths were not time-dependent. CONCLUSION: We believe this analysis extends our understanding of the temporal impact of proximal femoral fracture and its surgical management upon outcome beyond the previously accepted standard (30 days) and supports the use of a new, more relevant timescale for this high risk group of patients. It also highlights the need for planning and continuing physiotherapy, respiratory exercises and other chest-protective measures from 31 to 100 days.

Return to sports after valgus osteotomy of the knee joint in patients with medial unicompartmental osteoarthritis.

PURPOSE: The aim of this article was to evaluate the resumption of physical activity and sports after valgus osteotomy for medial femorotibial osteoarthritis. METHODS: This series is composed of 83 patients, with 27 females and 56 males. The mean age was 50.4 ± 9.53 years (32-67) at the time of operation. Before the onset of symptoms of knee osteoarthritis, four (4.8%) patients practiced a competitive sport, 44 (53%) one (or more) recreational sport on a regular basis, 17 (20%) occasionally and 18 (21.6%) did not practice any sport but were active. Sixty-two opening wedge high tibial osteotomies were performed as well as 21 double level osteotomies for severe deformity. All the osteotomies were computer-assisted in order to reach the best overcorrection. RESULTS: At a mean follow up of 5.75 ± 1.3 years (five to nine years), 71 patients (85.5%) resumed sporting activities and 66 (79.5%) felt they had found a sporting level equal to the level prior surgery. The mean Lysholm score increased from 62.51 ± 15.53 points (30-100) pre-operatively to 90.49 ± 8.62 points (55-100) postoperatively (p < 0.001). The Tegner and UCLA scores didn't decrease significantly after surgery (4.53 and 7.14 pre-operatively versus 4.1 and 6.55 postoperatively, p = 0.07 and 0.09). The mean postoperative KOO score was 73.52 ± 17.20. The frequency of sports sessions per week (2.36 ± 1.6) did not decrease significantly after surgery (2.13 sessions, p = 0.34). On the other hand, the duration of activities decreased significantly from 4.68 hours/week ± 4.25 to 3.48 hours/week (p = 0.04). Of the patients who practiced running before surgery 85% (17 of 20) were able to resume this activity. CONCLUSION: This study demonstrates that knee osteotomies for medial femorotibial osteoarthritis allow the resumption of sustained physical activity such as jogging or skiing downhill in a majority of patients.

Characterization of the cartilage DNA methylome in knee and hip osteoarthritis.

OBJECTIVE: The aim of this study was to characterize the genome-wide DNA methylation profile of chondrocytes from knee and hip cartilage obtained from patients with osteoarthritis (OA) and hip cartilage obtained from patients with femoral neck fracture, providing the first comparison of DNA methylation between OA and non-OA hip cartilage, and between OA hip and OA knee cartilage. METHODS: The study was performed using the Illumina Infinium HumanMethylation450 BeadChip array, which allows the annotation of ∼480,000 CpG sites. Genome-wide methylation was assessed in chondrocyte DNA extracted from 23 hip OA patients, 73 knee OA patients, and 21 healthy hip control patients with femoral neck fracture. RESULTS: Analysis revealed that chondrocytes from the hip cartilage of OA patients and healthy controls have unique methylation profiles, with 5,322 differentially methylated loci (DMLs) identified between the 2 groups. In addition, a comparison between hip and knee OA chondrocytes revealed 5,547 DMLs between the 2 groups, including DMLs in several genes known to be involved in the pathogenesis of OA. Hip OA samples were found to cluster into 2 groups. A total of 15,239 DMLs were identified between the 2 clusters, with an enrichment of genes involved in inflammation and immunity. Similarly, we confirmed a previous report of knee OA samples that also clustered into 2 groups. CONCLUSION: We demonstrated that global DNA methylation using a high-density array can be a powerful tool in the characterization of OA at the molecular level. Identification of pathways enriched in DMLs between OA and OA-free cartilage highlight potential etiologic mechanisms that are involved in the initiation and/or progression of the disease and that could be therapeutically targeted.

Lateral tenodesis combined with anterior cruciate ligament reconstruction using a unique semitendinosus and gracilis transplant.

PURPOSE: The aim of this study was to assess the anatomical results, functional results and the incidence of arthritis of a mixed intra- and extra-articular hamstring tendon based reconstruction for anterior instability of the knee. METHODS: This retrospective study consists of 100 knees in 99 patients (22 female and 77 male) operated upon between November 2003 and March 2006. The average age was 29.7 ± 10.4 years and the average interval between injury and surgery was 26.6 ± 41.8 months (2-240). In our technique, the semitendinosus and gracilis tendons were left attached to the tibia and by means of a lateral transcondylar tunnel posterior and inferior to the proximal attachment of the lateral collateral ligament were passed around the knee before being sutured to the fascia lata at the level of Gerdy's tubercle. RESULTS: Sixty-eight knees were re-examined at an average follow-up of 76 ± 12 months. The average differential anterior drawer test at the last review was 2.5 ± 3.4 mm (p < 0.0001). Of the patients 75 % had a negative pivot shift test, 21 % a gliding test and 4 % a clear positive test (p < 0.0001); 84 % of patients had an International Knee Documentation Committee (IKDC) score rated A or B. The average IKDC subjective score was 90 ± 9 (60-100). CONCLUSIONS: Mixed intra- and extra-articular reconstructions using hamstring grafts allow the knee to be stabilised in the sagittal plane and the rotatory instability to be controlled in the majority of cases. Only very minor progression of arthritic changes at an average 76 ± 12 months was seen.

The assessment of neutrophil CD64 count as an early warning marker of joint replacement infection.

120,000 hip and knee replacements are performed each year in the UK and more than 1 % of these require revision surgery due to infection. Current diagnostic tests used to diagnose infection of joint replacements, including the current gold standard C-reactive protein, which offers poor specificity when diagnosing infection in the post-operative period. In the post-operative period these tests are unable to differentiate between physiological inflammation and infection of the replacement. Early treatment through antibiotic and washout therapy is essential to eradicate infection, saving the patient and the NHS the stress of revision surgery, which offers a much poorer prognosis than the original operative procedure. Thus, a superior marker is required and CD64 has been proposed to fulfil the necessary requirements of an effective marker. Data from several studies utilising a flow cytometer support the view that CD64 is firstly, a good marker of systemic infection and secondly, when studied in conjunction with musculoskeletal infections alone, is a sensitive and specific marker of this type of infection. However, meta-analysis of studies in this field concludes that more highly powered studies are needed before definite conclusions can be drawn. Despite this, the studies do portray a strong case for CD64 being the future of diagnosis of post-operative infection.

Results of a French multicentre retrospective experience with four hundred and eighteen failed unicondylar knee arthroplasties.

PURPOSE: By means of a multicentre retrospective study based on the failure of 418 aseptic unicondylar knee arthroplasties (UKA) our aims were to present the different types of revision procedure used in failed UKAs, to establish a clear operative strategy for each type of revision and to better define the indications for each type of revision. METHODS: Aseptic loosening was the principal cause of failure (n = 184, 44%) of which 99 cases were isolated tibial loosening (23.5 % of the whole series and 54% of all loosening), 25 were isolated femoral loosening (six and 13.6%) and 60 were both femoral and tibial loosening (14.3 and 32.6%). The next most common causes of failure were progression of arthritis (n = 56, 13.4%), polyethylene wear (n = 53, 12.7%), implant positioning errors (n = 26), technical difficulties (n = six) and implant failure (n = 16, 3.8% of cases). Data collection was performed online using OrthoWave software (Aria, Bruay Labuissiere, France), which allows collection of all details of the primary and revision surgery to be recorded. RESULTS: A total of 426 revisions were performed; 371 patients underwent revision to a total knee arthroplasty (TKA) (87%), 33 patients (7.7%) were revised to an ipsilateral UKA, 11 (2.6%) patients underwent contralateral UKA (ten) or patellofemoral arthroplasty (one) and 11 patients (2.6%) underwent revision without any change in implants. CONCLUSIONS: Before considering a revision procedure it is important to establish a definite cause of failure in order to select the most appropriate revision strategy. Revision to a TKA is by far the most common strategy for revision of failed UKA but by no means the only available option. Partial revisions either to an alternative ipsilateral UKA or contralateral UKA are viable less invasive techniques, which in carefully selected patients and in experienced hands warrant consideration.

Navigation of the tibial plateau alone appears to be sufficient in computer-assisted unicompartmental knee arthroplasty.

PURPOSE: The aim of this study was to present our technique to implant unicompartmental knee arthroplasty (UKA) using navigation and to give our first results regarding the accuracy of the device. METHODS: A total of 33 patients with medial femorotibial osteoarthritis (31) or avascular necrosis (2) were included in this study. The mean preoperative hip-knee-ankle (HKA) angle was 172.7 ± 2.2° (range 167-177°) and the preoperative planning aimed to reach an HKA angle between 175 and 179° (177 ± 2°), a tibial varus at 3 ± 1°, which means a tibial mechanical angle (TMA) close to 87 ± 1°, and posterior tibial slope at 3 ± 2°. In all cases, we used the OrthoPilot® device with dedicated software allowing us to navigate only the tibial plateau. RESULTS: The preoperative plan was reached in 93.9 % of cases for HKA angle, 84.8 % for TMA and 100 % for the posterior slope. CONCLUSIONS: Unicompartmental knee navigation is reliable. The navigation of only the tibial bone cut is a reasonable option as has been shown in this study. Its role is invaluable in the positioning of mobile-bearing UKA, where the risk of overcorrection should not be underestimated.

Revision following patello-femoral arthoplasty.

PURPOSE: To describe the population of patients undergoing patello-femoral arthroplasty (PFA) revision and the reasons for which these implants are being revised. To compare this information with the observed failure patterns described in other national registries and with those seen for total knee replacement (TKR). METHODS: Using data accessed from the National Joint Registry for England and Wales, we identified 4634 primary PFA implanted between 1 April 2003 and 30 June 2010. As of 1 July 2010, 195 PFAs had been revised. The epidemiology of PFA revision is described with specific emphasis upon the reasons for revision. RESULTS: The median age at revision was 61 years (145 F:50 M). Revision occurred at a median of 2.0 years following primary surgery. Sixty of the 98 centres (61%) performing PFA revisions undertook only one such procedure. The 195 revisions were undertaken by 140 different consultants. Unexplained pain was the reason for revision in 46% of cases where a reason was stated. Progression of tibio-femoral arthritis was seen in only 14% of cases. Undiagnosed pain remained the most common reason for revision irrespective of patient age and time to revision, and was twice as common for PFA revision when compared to a matched group of failed TKR (43% vs. 19%, P < 0.001). CONCLUSIONS: Unexplained pain is the principal indication for early revision of the failing PFA. The high proportion of revisions performed for unexplained pain raises questions about the adequacy of surgical selection for patients undergoing PFA. LEVEL OF EVIDENCE: Retrospective comparative study, Level III.