Aims. The aim of this study was to investigate whether wear and backside deformation of polyethylene (PE) tibial inserts may influence the cement cover of tibial trays of explanted total knee arthroplasties (TKAs). Methods. At our retrieval centre, we measured changes in the wear and deformation of PE inserts using coordinate measuring machines and light microscopy. The amount of cement cover on the backside of tibial trays was quantified as a percentage of the total surface. The study involved data from the explanted fixed-bearing components of four widely used contemporary designs of TKA (Attune, NexGen, Press Fit Condylar (PFC), and Triathlon), revised for any indication, and we compared them with components that used previous generations of PE.
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.
Wear of the polyethylene (PE) tibial insert of total knee arthroplasty (TKA) increases the risk of revision surgery with a significant cost burden on the healthcare system. This study quantifies wear performance of tibial inserts in a large and diverse series of retrieved TKAs to evaluate the effect of factors related to the patient, knee design, and bearing material on tibial insert wear performance. An institutional review board-approved retrieval archive was surveyed for modular PE tibial inserts over a range of in vivo duration (mean 58 months (0 to 290)). Five knee designs, totalling 1,585 devices, were studied. Insert wear was estimated from measured thickness change using a previously published method. Linear regression statistical analyses were used to test association of 12 patient and implant design variables with calculated wear rate.Aims
Methods
The aim of this study was to compare any differences in the primary outcome (biphasic flexion knee moment during gait) of robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) at one year post-surgery. A total of 76 patients (34 bi-UKA and 42 TKA patients) were analyzed in a prospective, single-centre, randomized controlled trial. Flat ground shod gait analysis was performed preoperatively and one year postoperatively. Knee flexion moment was calculated from motion capture markers and force plates. The same setup determined proprioception outcomes during a joint position sense test and one-leg standing. Surgery allocation, surgeon, and secondary outcomes were analyzed for prediction of the primary outcome from a binary regression model.Aims
Methods
Single-stage revision total knee arthroplasty (rTKA) is gaining popularity in treating chronic periprosthetic joint infections (PJIs). We have introduced this approach to our clinical practice and sought to evaluate rates of reinfection and re-revision, along with predictors of failure of both single- and two-stage rTKA for chronic PJI. A retrospective comparative cohort study of all rTKAs for chronic PJI between 1 April 2003 and 31 December 2018 was undertaken using prospective databases. Patients with acute infections were excluded; rTKAs were classified as single-stage, stage 1, or stage 2 of two-stage revision. The primary outcome measure was failure to eradicate or recurrent infection. Variables evaluated for failure by regression analysis included age, BMI, American Society of Anesthesiologists grade, infecting organisms, and the presence of a sinus. Patient survivorship was also compared between the groups.Aims
Methods
Genu varum in the achondroplastic patient has a complex and multifactorial aetiology. There is little mention in the literature of the role of fibular overgrowth. Using the ratio of fibular to tibial length as a measurement of possible fibular overgrowth, we have related it to the development of genu varum. Full-length standing anteroposterior radiographs of 53 patients with achondroplasia were analysed. There were 30 skeletally-immature and 23 skeletally-mature patients.
This study aimed to determine outcomes of isolated tibial insert exchange (ITIE) during revision total knee arthroplasty (TKA). From 1985 to 2016, 270 ITIEs were performed at one institution for instability (55%, n = 148), polyethylene wear (39%, n = 105), insert fracture/dissociation (5%, n = 14), or stiffness (1%, n = 3). Patients with component loosening, implant malposition, infection, and extensor mechanism problems were excluded.Aims
Methods
Vitamin E-infused highly cross-linked polyethylene (E1) has recently been introduced in total knee arthroplasty (TKA). An in vitro wear simulator study showed that E1 reduced polyethylene wear. However there is no published information regarding in vivo wear. Previous reports suggest that newly introduced materials which reduce in vitro polyethylene wear do not necessarily reduce in vivo polyethylene wear. To assist in the evaluation of the newly introduced material before widespread use, we established an in vivo polyethylene wear particle analysis for TKA. The aim of this study was to compare in vivo polyethylene wear particle generation between E1 and conventional polyethylene (ArCom) in TKA. A total of 34 knees undergoing TKA (17 each with ArCom or E1) were investigated. Except for the polyethylene insert material, the prostheses used for both groups were identical. Synovial fluid was obtained at a mean of 3.4 years (SD 1.3) postoperatively. The in vivo polyethylene wear particles were isolated from the synovial fluid using a previously validated method and examined by scanning electron microscopy.Aims
Methods
The purpose of this study was to develop a personalized outcome prediction tool, to be used with knee arthroplasty patients, that predicts outcomes (lengths of stay (LOS), 90 day readmission, and one-year patient-reported outcome measures (PROMs) on an individual basis and allows for dynamic modifiable risk factors. Data were prospectively collected on all patients who underwent total or unicompartmental knee arthroplasty at a between July 2015 and June 2018. Cohort 1 (n = 5,958) was utilized to develop models for LOS and 90 day readmission. Cohort 2 (n = 2,391, surgery date 2015 to 2017) was utilized to develop models for one-year improvements in Knee Injury and Osteoarthritis Outcome Score (KOOS) pain score, KOOS function score, and KOOS quality of life (QOL) score. Model accuracies within the imputed data set were assessed through cross-validation with root mean square errors (RMSEs) and mean absolute errors (MAEs) for the LOS and PROMs models, and the index of prediction accuracy (IPA), and area under the curve (AUC) for the readmission models. Model accuracies in new patient data sets were assessed with AUC.Aims
Methods
This study aimed to identify the tibial component and femoral component coronal angles (TCCAs and FCCAs), which concomitantly are associated with the best outcomes and survivorship in a cohort of fixed-bearing, cemented, medial unicompartmental knee arthroplasties (UKAs). We also investigated the potential two-way interactions between the TCCA and FCCA. Prospectively collected registry data involving 264 UKAs from a single institution were analyzed. The TCCAs and FCCAs were measured on postoperative radiographs and absolute angles were analyzed. Clinical assessment at six months, two years, and ten years was undertaken using the Knee Society Knee score (KSKS) and Knee Society Function score (KSFS), the Oxford Knee Score (OKS), the 36-Item Short-Form Health Survey questionnaire (SF-36), and range of motion (ROM). Fulfilment of expectations and satisfaction was also recorded. Implant survivorship was reviewed at a mean follow-up of 14 years (12 to 16). Multivariate regression models included covariates, TCCA, FCCA, and two-way interactions between them. Partial residual graphs were generated to identify angles associated with the best outcomes. Kaplan-Meier analysis was used to compare implant survivorship between groups.Aims
Methods
The practice of alternating operating theatres has long been used to reduce surgeon idle time between cases. However, concerns have been raised as to the safety of this practice. We assessed the payments and outcomes of total knee arthroplasty (TKA) performed during overlapping and nonoverlapping days, also comparing the total number of the surgeon’s cases and the total time spent in the operating theatre per day. A retrospective analysis was performed on the Centers for Medicare & Medicaid Services (CMS) Limited Data Set (LDS) on all primary elective TKAs performed at the New England Baptist Hospital between January 2013 and June 2016. Using theatre records, episodes were categorized into days where a surgeon performed overlapping and nonoverlapping lists. Clinical outcomes, economic outcomes, and demographic factors were calculated. A regression model controlling for the patient-specific factors was used to compare groups. Total orthopaedic cases and aggregate time spent operating (time between skin incision and closure) were also compared.Aims
Materials and Methods
Adductor canal block (ACB) has emerged as an alternative to femoral nerve block (FNB) for analgesia after total knee arthroplasty (TKA). The optimal duration of maintenance of the ACB is still questionable. The purpose of this study was to compare the analgesic benefits and physiotherapy (PT) outcomes of single-shot ACB to two different regimens of infusion of the continuous ACB, 24-hour and 48-hour infusion. This was a prospective, randomized, unblinded study. A total of 159 American Society of Anesthesiologists (ASA) physical status I to III patients scheduled for primary TKA were randomized to one of three study groups. Three patients did not complete the study, leaving 156 patients for final analysis. Group A (n = 53) was the single-shot group (16 female patients and 37 male patients with a mean age of 63.9 years (Aims
Patients and Methods
The aim of this study was to evaluate the long-term inducible
displacement of cemented tibial components ten years after total
knee arthroplasty (TKA). A total of 15 patients from a previously reported prospective
trial of fixation using radiostereometric analysis (RSA) were examined
at a mean of 11 years (10 to 11) postoperatively. Longitudinal supine
RSA examinations were acquired at one week, one year, and two years
postoperatively and at final follow-up. Weight-bearing RSA examinations
were also undertaken with the operated lower limb in neutral and
in maximum internal rotation positions. Maximum total point motion
(MTPM) was calculated for the longitudinal and inducible displacement examinations
(supine Aims
Patients and Methods
Early and accurate prediction of hospital length-of-stay
(LOS) in patients undergoing knee replacement is important for economic
and operational reasons. Few studies have systematically developed
a multivariable model to predict LOS. We performed a retrospective
cohort study of 1609 patients aged ≥ 50 years who underwent elective,
primary total or unicompartmental knee replacements. Pre-operative
candidate predictors included patient demographics, knee function,
self-reported measures, surgical factors and discharge plans. In
order to develop the model, multivariable regression with bootstrap
internal validation was used. The median LOS for the sample was
four days (interquartile range 4 to 5). Statistically significant
predictors of longer stay included older age, greater number of comorbidities,
less knee flexion range of movement, frequent feelings of being
down and depressed, greater walking aid support required, total
( Cite this article:
The aim of this study was to examine the loading
of the other joints of the lower limb in patients with unilateral osteoarthritis
(OA) of the knee. We recruited 20 patients with no other symptoms
or deformity in the lower limbs from a consecutive cohort of patients
awaiting knee replacement. Gait analysis and electromyographic recordings were
performed to determine moments at both knees and hips, and contraction
patterns in the medial and lateral quadriceps and hamstrings bilaterally.
The speed of gait was reduced in the group with OA compared with
the controls, but there were only minor differences in stance times
between the limbs. Patients with OA of the knee had significant
increases in adduction moment impulse at both knees and the contralateral
hip (adjusted p-values: affected knee: p <
0.01, unaffected knee
p = 0.048, contralateral hip p = 0.03), and significantly increased
muscular co-contraction bilaterally compared with controls (all
comparisons for co-contraction, p <
0.01). The other major weight-bearing joints are at risk from abnormal
biomechanics in patients with unilateral OA of the knee. Cite this article:
The aim of this study was to determine the association
between the Oxford knee score (OKS) and direct assessment of outcome,
and to examine how this relationship varied at different time-points
following total knee replacement (TKR). Prospective data consisting
of the OKS, numerical rating scales for ‘worst pain’ and ‘perceived
mean daily pain’, timed functional assessments (chair rising, stairs
and walking ability), goniometry and lower limb power were recorded
for 183 patients pre-operatively and at six, 26 and 52 weeks post-operatively.
The OKS was influenced primarily by the patient’s level of pain
rather than objective functional assessments. The relationship between report
of outcome and direct assessment changed over time: R2 =
35% pre-operatively, 44% at six weeks, 57% at 26 weeks and 62% at
52 weeks. The relationship between assessment of performance and report
of performance improved as the patient’s report of pain diminished,
suggesting that patients’ reporting of functional outcome after
TKR is influenced more by their pain level than their ability to
accomplish tasks.
The purpose of this study was to report the outcome
of ‘isolated’ anterior cruciate ligament (ACL) ruptures treated with
anatomical endoscopic reconstruction using hamstring tendon autograft
at a mean of 15 years (14.25 to 16.9). A total of 100 consecutive
men and 100 consecutive women with ‘isolated’ ACL rupture underwent
four-strand hamstring tendon reconstruction with anteromedial portal
femoral tunnel drilling and interference screw fixation by a single
surgeon. Details were recorded pre-operatively and at one, two,
seven and 15 years post-operatively. Outcomes included clinical
examination, subjective and objective scoring systems, and radiological
assessment. At 15 years only eight of 118 patients (7%) had moderate
or severe osteo-arthritic changes (International Knee Documentation
Committee Grades C and D), and 79 of 152 patients (52%) still performed
very strenuous activities. Overall graft survival at 15 years was
83% (1.1% failure per year). Patients aged <
18 years at the
time of surgery and patients with >
2 mm of laxity at one year had
a threefold increase in the risk of suffering a rupture of the graft
(p = 0.002 and p = 0.001, respectively). There was no increase in
laxity of the graft over time. ACL reconstructive surgery in patients with an ‘isolated’ rupture
using this technique shows good results 15 years post-operatively
with respect to ligamentous stability, objective and subjective
outcomes, and does not appear to cause osteoarthritis.
Following arthroplasty of the knee, the patient’s
perception of improvement in symptoms is fundamental to the assessment
of outcome. Better clinical outcome may offset the inferior survival
observed for some types of implant. By examining linked National
Joint Registry (NJR) and patient-reported outcome measures (PROMs)
data, we aimed to compare PROMs collected at a minimum of six months
post-operatively for total (TKR: n = 23 393) and unicondylar knee
replacements (UKR: n = 505). Improvements in knee-specific (Oxford
knee score, OKS) and generic (EuroQol, EQ-5D) scores were compared
and adjusted for case-mix differences using multiple regression.
Whereas the improvements in the OKS and EQ-5D were significantly
greater for TKR than for UKR, once adjustments were made for case-mix
differences and pre-operative score, the improvements in the two
scores were not significantly different. The adjusted mean differences
in the improvement of OKS and EQ-5D were 0.0 (95% confidence interval (CI)
-0.9 to 0.9; p = 0.96) and 0.009 (95% CI -0.034 to 0.015; p = 0.37),
respectively. We found no difference in the improvement of either knee-specific
or general health outcomes between TKR and UKR in a large cohort
of registry patients. With concerns about significantly higher revision
rates for UKR observed in worldwide registries, we question the
widespread use of an arthroplasty that does not confer a significant
benefit in clinical outcome.
Smoking is known to have an adverse effect on wound healing and musculoskeletal conditions. This case-controlled study looked at whether smoking has a deleterious effect in the outcome of autologous chondrocyte implantation for the treatment of full thickness chondral defects of the knee. The mean Modified Cincinatti Knee score was statistically significantly lower in smokers (n = 48) than in non-smokers (n = 66) both before and after surgery (p <
0.05). Smokers experienced significantly less improvement in the knee score two years after surgery (p <
0.05). Graft failures were only seen in smokers (p = 0.016). There was a strong negative correlation between the number of cigarettes smoked and the outcome following surgery (Pearson’s correlation coefficient −0.65, p = 0.004). These results suggest that patients who smoke have worse pre-operative function and obtain less benefit from this procedure than non-smokers. The counselling of patients undergoing autologous chondrocyte implantation should include smoking, not only as a general cardiopulmonary risk but also because poorer results can be expected in smokers following this procedure.
Between 1987 and 2006 we performed a modified Thompson’s quadricepsplasty on 40 fracture-related stiff knees and followed the patients for a mean of 7.9 years (2 to 11.1). The factors affecting the final gain of movement were investigated. A total of 15 knees required lengthening of the rectus femoris. The mean flexion gain was 70.2° (42.3° to 112.5°). According to Judet’s criteria, the results were excellent in 30 knees, good in seven, and fair in three. The range of movement which was achieved intra-operatively was related to the gain of knee flexion on univariate analysis. Five patients had complications: deep infection in one, recurrent patellar dislocation in one, and rupture of the extensor mechanism in three. This modified technique gives satisfactory results. Achieving maximum knee flexion intra-operatively seems to be the most important factor in enhancing the outcome in patients with stiffness of the knee following fracture.
