How I do it: 1st stage revision TKA.

This article covers the key steps and decisions that we make when performing a 1st-stage revision Total Knee Arthroplasty (TKA) at the Avon Orthopaedic Centre and includes more detailed technique and tips regarding how we make our spacers. The first stage of a two-stage protocol should be done in a stable patient with information about the organism, and with the option of plastic surgery flap coverage if required. It should ideally be performed in the unit that is going to perform the second stage, and the operation note should document the soft-tissues, bone loss and extensor mechanism issues that will influence planning for the second stage. Nothing will make up for a bad debridement, so we focus on this as the key step for infection clearance. Infection clearance is equivalent between mobile and static spacers, but patients generally prefer having the better mobility and function of a mobile spacer. We recommend a mobile spacer, unless there is compromise to ligaments or extensor mechanism, or if bone loss is large. Whichever spacer you use, it should aim to: deliver appropriate antibiotics; allow stability, pain relief and some function and weight-bearing prior to the second stage. Doing a good technical job with the spacer is important because you do not want complications with the spacer to cause harm or necessitate a return to theatre or re-operation sooner than planned. Ideally the second stage should be performed when the surgeon & MDT team deem it appropriate clinically and when the patient is fit and ready for further surgery.

Systematic review of learning curves in robot-assisted surgery.

BACKGROUND: Increased uptake of robotic surgery has led to interest in learning curves for robot-assisted procedures. Learning curves, however, are often poorly defined. This systematic review was conducted to identify the available evidence investigating surgeon learning curves in robot-assisted surgery. METHODS: MEDLINE, Embase and the Cochrane Library were searched in February 2018, in accordance with PRISMA guidelines, alongside hand searches of key congresses and existing reviews. Eligible articles were those assessing learning curves associated with robot-assisted surgery in patients. RESULTS: Searches identified 2316 records, of which 68 met the eligibility criteria, reporting on 68 unique studies. Of these, 49 assessed learning curves based on patient data across ten surgical specialties. All 49 were observational, largely single-arm (35 of 49, 71 per cent) and included few surgeons. Learning curves exhibited substantial heterogeneity, varying between procedures, studies and metrics. Standards of reporting were generally poor, with only 17 of 49 (35 per cent) quantifying previous experience. Methods used to assess the learning curve were heterogeneous, often lacking statistical validation and using ambiguous terminology. CONCLUSION: Learning curve estimates were subject to considerable uncertainty. Robust evidence was lacking, owing to limitations in study design, frequent reporting gaps and substantial heterogeneity in the methods used to assess learning curves. The opportunity remains for the establishment of optimal quantitative methods for the assessment of learning curves, to inform surgical training programmes and improve patient outcomes.

ANTECEDENTES: La aceptación creciente de la cirugía robótica ha generado interés en las curvas de aprendizaje para los procedimientos asistidos por robot. Sin embargo, las curvas de aprendizaje a menudo están mal definidas. Esta revisión sistemática se realizó para identificar la evidencia disponible en relación a las curvas de aprendizaje del cirujano en la cirugía asistida por robot. MÉTODOS: En Febrero de 2018, se realizaron búsquedas en MEDLINE, Embase y Cochrane Library, de acuerdo con las recomendaciones PRISMA, junto con búsquedas manuales de congresos clave y de revisiones ya existentes. Los artículos elegibles fueron aquellos que evaluaron las curvas de aprendizaje asociadas con la cirugía asistida por robot efectuada en pacientes. RESULTADOS: Las búsquedas bibliográficas identificaron 2.316 registros de los cuales 68 cumplían los criterios de elegibilidad y correspondían a 68 estudios primarios. De estos 68 estudios, 49 evaluaron las curvas de aprendizaje basadas en datos de pacientes de 10 especialidades quirúrgicas. Los 49 estudios eran todos estudios observacionales, en su mayoría de un solo brazo (35/49 (71%)) e incluían pocos cirujanos. Las curvas de aprendizaje mostraban una notable heterogeneidad, variando entre procedimientos, estudios y parámetros analizados. Los estándares de presentación de informes fueron generalmente deficientes, con solo 17/49 (35%) cuantificando la experiencia previa. Los métodos utilizados para evaluar la curva de aprendizaje fueron heterogéneos, a menudo carecían de validación estadística y usaban terminología ambigua. CONCLUSIÓN: Las estimaciones de la curva de aprendizaje estaban sujetas a una considerable incertidumbre, careciendo de evidencia robusta por las limitaciones en el diseño del estudio, lagunas de información en los artículos y heterogeneidad sustancial en los métodos utilizados para evaluar las curvas de aprendizaje. Queda pendiente establecer métodos cuantitativos óptimos para evaluar las curvas de aprendizaje, informar de los programas de formación quirúrgica y mejorar los resultados del paciente.

Revision knee complexity classification-RKCC: a common-sense guide for surgeons to support regional clinical networking in revision knee surgery.

PURPOSE: There is considerable variation in practice throughout Europe in both the services provided and in the outcomes of Revision Knee Surgery. In the UK, a recent report published called get it right first time (GIRFT) aims to improve patient outcomes through providing high quality, cost-effective care, and reducing complications. This has led to the development of a classification system that attempts to classify the complexity of revision knee surgery, aiming to encourage and support regional clinical networking. METHODS: The revision knee classification system (RKCC) incorporates not only complexity, but also patient factors, the presence of infection, the integrity of the extensor mechanism, and the soft tissues. It then provides guidance for clinical network discussion. Reliability and reproducibility testing have been performed to establish the inter- and intra-observer variabilities using this classification. RESULTS: Good correlation between first attempt non-expert and experts, good intra-observer variability of non-expert, and an excellent correlation between second attempt non-expert and experts has been achieved. This supports the use of RKCC by both inexperienced and experienced surgeons. CONCLUSIONS: The revision knee complexity classification has been proposed that offers a common-sense approach to recognize the increasing complexity in revision TKR cases. It provides a methodological assessment of revision knee cases and support regional clinical networking and triage of appropriate cases to revision units or specialist centres. LEVEL OF EVIDENCE: Expert opinion, Level V.

The Avon patellofemoral joint arthroplasty: two- to 18-year results of a large single-centre cohort.

Aims: This study reports on the medium- to long-term implant survivorship and patient-reported outcomes for the Avon patellofemoral joint (PFJ) arthroplasty. Patients and Methods: A total of 558 Avon PFJ arthroplasties in 431 patients, with minimum two-year follow-up, were identified from a prospective database. Patient-reported outcomes and implant survivorship were analyzed, with follow-up of up to 18 years. Results: Outcomes were recorded for 483 implants (368 patients), representing an 86% follow-up rate. The median postoperative Oxford Knee Score (0 to 48 scale) was 35 (interquartile range (IQR) 25.5 to 43) and the median Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC, 0 to 100 scale) was 35 (IQR 25 to 53) at two years. There were 105 revisions, 61 (58%) for progression of osteoarthritis. All documented revisions were to primary knee systems without augmentation. The implant survival rate was 77.3% (95% confidence interval (CI) 72.4 to 81.7, number at risk 204) at ten years and 67.4% (95% CI 72.4 to 81.7 number at risk 45) at 15 years. Regression analysis of explanatory data variable showed that cases performed in the last nine years had improved survival compared with the first nine years of the cohort, but the individual operating surgeon had the strongest effect on survivorship. Conclusion: Satisfactory long-term results can be obtained with the Avon PFJ arthroplasty, with maintenance of patient-reported outcome measures (PROMs), satisfactory survival, and low rates of loosening and wear. Cite this article: Bone Joint J 2018;100-B:1162-7.

Survivorship and clinical outcome of the minimally invasive Uniglide medial fixed bearing, all-polyethylene tibia, unicompartmental knee arthroplasty at a mean follow-up of 7.3years.

BACKGROUND: Medial UKA performed in England and Wales represents seven to 11% of all knee arthroplasty procedures, and is most commonly performed using mobile-bearing designs. Fixed bearing eliminates the risk of bearing dislocation, however some studies have shown higher revision rates for all-polyethylene tibial components compared to those that utilize metal-backed implants. The aim of the study is to analyse survivorship and maximum eight-year clinical outcome of medial fixed bearing, Uniglide unicompartmental knee arthroplasty performed using an all-polyethylene tibial component with a minimal invasive approach. METHODS: Between 2002 and 2009, 270 medial fixed UKAs were performed in our unit. Patients were reviewed pre-operatively, five and eight years post-operatively. Clinical and radiographic reviews were carried out. Patients' outcome scores (Oxford, WOMAC and American Knee Score) were documented in our database and analysed. RESULTS: Survival and clinical outcome data of 236 knees with a mean of 7.3years follow-up are reported. Every patient with less than 4.93years of follow-up underwent a revision. The patients' average age at the time of surgery was 69.5years. The American Knee Society Pain and Function scores, the Oxford Knee Score and the WOMAC score all improved significantly. The five-year survival rate was 94.1% with implant revision surgery as an end point. The estimated 10years of survival rate is 91.3%. Fourteen patients were revised before the five-year follow-up. CONCLUSION: Fixed bearing Uniglide UKA with an all-polyethylene tibial component is a valuable tool in the management of a medial compartment osteoarthritis, affording good short-term survivorship. Level of evidence IV.

Bristol index of patellar width to thickness (BIPWiT): a reproducible measure of patellar thickness from adult MRI.

BACKGROUND: The restoration of an adequate patellar thickness is a key to the successful outcome of knee arthroplasty. This study investigated the relationship between the thickness of the native patellar and medial-lateral patellar width using magnetic resonance imaging (MRI). METHODS: 75 MRI scans of young adults, with an average age of 27 (range 16-40) were studied. Exclusion criteria included a diagnosis of degenerative joint disease, patello-femoral pathology or age under 16/over 40 (170 patients). The bony thickness of the patellar, the chondral thickness and patellar width were measured, as was the location of maximal patellar thickness. Inter/intraobserver variability was calculated and correlation analysis was performed. RESULTS: We found a strong correlation between patellar width and thickness (bone plus cartilage) (Pearson 0.75, P<0.001). The mean width to thickness ratio was 1.8:1 (standard deviation 0.1, 95% confidence interval 1.78-1.83). Without cartilage the ratio was 2.16:1 (SD 0.15, 95% CI 2.11-2.21), correlation was moderate (Pearson 0.59, P<0.001). The average maximal patellar cartilage thickness was 4.1mm (SD 1.3). CONCLUSION: The strong correlation and narrow confidence intervals for the ratio of patellar width to thickness, suggest that patellar width might be used as a guide for accurate restoration of patellar thickness during total knee or patello-femoral replacement. After removing osteophytes we would recommend a ratio of 1.8:1. Further work is required to establish whether there is a relationship between anterior knee pain post total knee arthroplasty and an abnormal patellar width:thickness ratio. LEVEL OF EVIDENCE: Level III.

Do long leg supine CT scanograms correlate with weight-bearing full-length radiographs to measure lower limb coronal alignment?

INTRODUCTION: The gold standard for measuring knee alignment is the lower limb mechanical axis (MA) using weight-bearing lower limb full-length x-ray (FLX). However, CT scanograms (CTS) are becoming increasingly popular in view of lower radiation exposure, speed of data acquisition and supine positioning. We compared the correlation and degree of agreement of knee joint coronal alignment using these two imaging modalities. METHOD: From our series of complex primary and revision knee arthroplasty patients, we selected those with both FLX and CTS recorded onto digital PACS. The coronal alignments were assessed in 24 knees and the valgus/varus angles relative to the MA were measured. Results were analysed statistically using the paired samples t-test, Pearson's correlation coefficient, intra-class correlation coefficient, Cohen's kappa and Passing and Bablok regression to assess potential equality of methods. RESULTS: The mean MA was 180.5° (165°-200°) for the CTS and 181° (164°-202°) for the FLX. The CTS MA angle data between the assessors were highly correlated (r=0.971, p <0.001) as were FLX MA angle measurements (r=0.988, p <0.001). 41.7% of the CTS and 37.5% of the FLX were in varus alignment, while 50% of the CTS and 43.8% of the FLX were in valgus alignment. Malalignment >5° was revealed by 18.8% of the CTS and 35.4% of the FLX. CONCLUSION: Overall, good agreement was observed in MA angle data between the two imaging modalities, but reproducibility may be problematic. In the malaligned limb, weight-bearing FLX still remains a vital imaging modality. CTS should be used with caution in view of the under-detection of malalignment.

Long-term (ten- to 15-year) outcome of arthroscopically assisted Elmslie-Trillat tibial tubercle osteotomy.

We present the ten- to 15-year follow-up of 31 patients (34 knees), who underwent an Elmslie-Trillat tibial tubercle osteotomy for chronic, severe patellar instability, unresponsive to non-operative treatment. The mean age of the patients at the time of surgery was 31 years (18 to 46) and they were reviewed post-operatively, at four years (2 to 8) and then at 12 years (10 to 15). All patients had pre-operative knee radiographs and Cox and Insall knee scores. Superolateral portal arthroscopy was performed per-operatively to document chondral damage and after the osteotomy to assess the stability of the patellofemoral joint. A total of 28 knees (82%) had a varying degree of damage to the articular surface. At final follow-up 25 patients (28 knees) were available for review and underwent clinical examination, radiographs of the knee, and Cox and Insall scoring. Six patients who had no arthroscopic chondral abnormality showed no or only early signs of osteoarthritis on final radiographs; while 12 patients with lower grade chondral damage (grade 1 to 2) showed early to moderate signs of osteoarthritis and six out of ten knees with higher grade chondral damage (grade 3 to 4) showed marked evidence of osteoarthritis; four of these had undergone a knee replacement. In the 22 patients (24 knees) with complete follow-up, 19 knees (79.2%) were reported to have a good or excellent outcome at four years, while 15 knees (62.5%) were reported to have the same at long-term follow-up. The functional and radiological results show that the extent of pre-operatively sustained chondral damage is directly related to the subsequent development of patellofemoral osteoarthritis.

Iatrogenic surface damage during femoral component impaction in total knee arthroplasty.

Application of prosthesis components during knee arthroplasty surgery involves impacting the femoral component using an impaction device and a heavy mallet. This could damage the component and may therefore be of concern to knee surgeons. Using a drop tower with a set-up that mimics the impaction generated clinically when a surgeon hits the femoral component, we investigated the possible surface damage to the femoral component. Three parameters were obtained and compared with a contact profilometer to characterize the roughness: R(a), R(pk) and R(z). The effect of the impacts on the contour of the femoral components was also investigated. After 3 series of impactions, no difference in surface roughness of the femoral component important enough to increase the wear rate could be detected neither for Cobalt Chrome or Oxidized Zirconium components. Our study therefore indicates that impacting the femoral component during TKA does not alter the component's surface roughness.

Measurements of in vivo intra-articular gentamicin levels from antibiotic loaded articulating spacers in revision total knee replacement.

Previous in vitro studies have found high levels of antibiotic release in the days immediately following implantation of antibiotic loaded articulating spacers. However there are relatively few data describing the elution profile beyond this immediate period. This study was designed to measure if gentamicin levels continue to be clinically therapeutic after an extended period following in vivo implantation. Twelve patients received a gentamicin loaded articulating spacer between a 1st and 2nd stage revision total knee arthroplasty. At the 2nd stage procedure synovial fluid and blood samples were collected and assayed for the presence of gentamicin. The second stage revision occurred at a median of 99 days following spacer insertion. The median intra-articular gentamicin levels were 0.46 mg/L (0.24 to 2.36 mg/L) which would be considered therapeutic. There were no cases of reinfection. In this study, preformed articulating spacers containing gentamicin provided therapeutic concentrations in the synovial fluid surrounding the joint throughout the period of implantation. These data confirm the observations from in vitro studies, where a prolonged elution profile was observed for such spacers.

Does the joint line matter in revision total knee replacement?

We identified 148 patients who had undergone a revision total knee replacement using a single implant system between 1990 and 2000. Of these 18 patients had died, six had developed a peri-prosthetic fracture and ten had incomplete records or radiographs. This left 114 with prospectively-collected radiographs and Bristol knee scores available for study. The height of the joint line before and after revision total knee replacement was measured and classified as either restored to within 5 mm of the pre-operative height or elevated if it was positioned more than 5 mm above the pre-operative height. The joint line was elevated in 41 knees (36%) and restored in 73 (64%). Revision surgery significantly improved the mean Bristol knee score from 41.1 (SD 15.9) pre-operatively to 80.5 (SD 15) post-operatively (p < 0.001). At one year post-operatively both the total Bristol knee score and its functional component were significantly better in the restored group than in the elevated group (p < 0.01). Overall, revision from a unicondylar knee replacement required less use of bone graft, fewer component augments, restored the joint line more often and gave a significantly better total Bristol knee score (p < 0.02) and functional score (p < 0.01) than revision from total knee replacement. Our findings show that restoration of the joint line at revision total knee replacement gives a significantly better result than leaving it unrestored by more than 5 mm. We recommend the greater use of distal femoral augments to help to achieve this goal.

A comparison of patient based outcome following knee arthrodesis for failed total knee arthroplasty and revision knee arthroplasty.

Arthrodesis of the knee is an infrequently performed operation perceived by both patient and surgeon to have a poor outcome. This study compares functional outcome of knee arthrodesis following failed primary arthroplasty with that of revision knee arthroplasty in a matched patient group. Outcome was measured using the SF12 and Oxford Knee Score. Twelve patients underwent arthrodesis, of which eight were available for functional review at a mean of 53 months. No significant difference was found between the outcome scores of the two groups, although it is recognised that the numbers involved were low. Arthrodesis of the knee may be considered as a surgical option following failed arthroplasty when factors are present that may mitigate against an optimal result following revision knee arthroplasty.

Obesity and knee arthroplasty.

Obesity has been shown to be a risk factor for knee osteoarthritis. Total knee arthroplasty in the obese patient has given rise to some controversy in terms of perioperative risks, and the longevity of the implants. We reviewed the salient literature on this subject regarding the impact of obesity on the knee, the outcome of TKA in the obese patient, and on the effect of TKA on pre-existing obesity. While increased risk of complications and early implant failure has been shown by some studies in the morbidly obese, there is no definite cut-off in Body Mass Index which accurately separates high-risk from low-risk individuals, although there is evidence that heavier patients are at greater risk. We have seen that although postoperative scores are lower in the obese group, these patients may derive considerable improvement in pain following TKA. While not condoning the obese patient with knee arthritis being denied an effective pain-relieving procedure, we stress the importance of appropriate risk-counselling of these patients, and allowance within the healthcare system for the extra financial and service implications placed by the obese TKA patient.

Observed kneeling ability after total, unicompartmental and patellofemoral knee arthroplasty: perception versus reality.

Kneeling is an important function of the knee, but little information is available on ability to kneel after different knee arthroplasty procedures. Previous work has asked patients about their kneeling ability; in this study it was objectively assessed. One hundred and twenty two patients - 38 having had total knee replacement (TKR), 53 unicompartmental knee replacement (UKR), 31 patello-femoral replacement (PFR) - were observed trying to kneel at 90 degrees on a chair, at 90 degrees on the floor, and at 120 degrees on the floor. Only 37% of patients thought they could kneel, whereas 81% were actually able to kneel ( p<0.001). Ability to kneel on the chair and on the floor at 90 degrees was significantly better than perceived ability for all prosthesis types ( p<0.001). Kneeling at 120 degrees showed no difference between perception and reality except for the PFR group ( p<0.05). In all positions, increased range of movement significantly improved kneeling ability ( p<0.001). Kneeling ability in men was significantly better than in women ( p<0.001). Patient-centred questionnaires do not accurately document kneeling ability after knee arthroplasty.

Post-operative drainage after cemented, hybrid and uncemented total knee replacement.

We recorded the total and 8-hourly post-operative drainage of 100 consecutive total knee replacements (33 cemented, 35 hybrid and 32 uncemented). The cemented, hybrid and uncemented prostheses had mean total drainage of 745, 1035 and 1220 ml, respectively. The difference in drainage between cemented and both hybrid and uncemented was statistically significant (P<0.05 and P<0.001). A significantly higher percentage of drainage occurred in the first 8-h period in the hybrid and uncemented groups. Total drainage in the cemented group was lower, but occurred more slowly, with a significantly higher percentage of drainage in the 17-48-h post-operative period when compared with the uncemented group (P<0.05). Within the cemented group, posterior-stabilised implants drained significantly more than those with an AP-lipped tibial insert (P<0.05). This information has implications for planning of blood product usage and timing of drain tube removal.

Can knees kneel? Kneeling ability after total, unicompartmental and patellofemoral knee arthroplasty.

This study investigates patients' perception of kneeling ability before and at 1 and 2 years after total, unicompartmental knee replacement (UKR) and patellofemoral knee replacement (PFR), for osteoarthritis. Kneeling is an important function of the knee joint required for many daily activities and inability to kneel after knee surgery is a frequent cause of dissatisfaction. Data were prospectively collected on 253 knees. A kneeling score was obtained by analysis of the relevant section of the Oxford knee score. Scores were obtained pre-operatively and at 1 and 2 years post-operatively. Absolute values and change following surgery were recorded. Correlations with pain and other knee functions were also made. Kneeling ability prior to surgery was poor in all 3 groups (80% found it extremely difficult or impossible to kneel) and improved in all groups after surgery (20% had little or no difficulty to kneel at 2 years). Kneeling ability was best in UKR and worst in PFR. These results suggest that kneeling ability in osteoarthritic patients is poor but improves with knee arthroplasty surgery, however the majority of patients will still have difficulty in kneeling.

Arthrodesis of the knee using a custom-made intramedullary coupled device.

Nine patients underwent arthrodesis of the knee using customised coupled nail (the Mayday arthrodesis nail), five after infected arthroplasty, one following failed arthrodesis, one for intractable anterior knee pain, one for Charcot instability and one after trauma. Comparison was made with 17 arthrodeses, eight undertaken using external fixation, four with dual compression plates, and five with long Kütntscher nails. Union was achieved in all patients (100%) at a mean time of ten months using the customised implant. There were no complications despite early weight-bearing. No further procedures were required. This contrasted with a rate of union of 53% and a complication rate of 76% with alternative techniques. Of this second group, 76% required a further operative procedure. We compared the Mayday arthrodesis nail with other techniques of arthrodesis of the knee. The differences in the need for further surgery and occurrence of complications were statistically significant (p < 0.001), and differences in the rate of nonunion and inpatient stay of less than three weeks were also significant (p < 0.05) using Fisher's exact test. We conclude that a customised coupled intramedullary nail can give excellent stability allowing early weight-bearing, and results in a high rate of union with minimal postoperative complications.

Use of modified Ilizarov olive wires as pushing wires.

We describe a technique for the use of modified Ilizarov olive wires to stabilize bone fragments or segments or to act as a "motor" to move individual bone fragments. This technique was used in twelve patients with severe articular or comminuted open fractures referred to the unit for reconstruction with the Ilizarov frame. Six patients had comminuted plafond fractures of the tibia, and three had tibial plateau fractures. In these cases the articular fragments were reduced and stabilized until union. The modified pushing olive wire is a valuable adjunct to the Ilizarov frame.