Effect of Intravenous Zoledronic Acid on Total Knee Replacement in Patients With Symptomatic Knee Osteoarthritis and Without Severe Joint Space Narrowing: A Prespecified Secondary Analysis of a Two-Year, Multicenter, Double-Blind, Placebo-Controlled Clinical Trial.

OBJECTIVE: To determine the effect of zoledronic acid (ZA) on the risk of total knee replacement (TKR) in patients with symptomatic knee osteoarthritis and without severe joint space narrowing (JSN). METHODS: We included 222 participants (mean age 62 years, 52% female) from the two-year Zoledronic Acid for Osteoarthritis Knee Pain trial (113 received 5 mg of ZA annually and 109 received placebo) conducted between November 2013 and October 2017. Primary TKR were identified until February 22, 2022. The effect of ZA on TKR risk was evaluated using Cox proportional hazard regression models. Because the treatment effect failed the proportional hazards assumption, a time-varying coefficients analysis for treatment was conducted by splitting the study into two periods (ie, within and after two years of randomization). RESULTS: Over a mean follow-up of seven years, 39% and 30% of participants had any TKR in the ZA and placebo groups, and 28% and 18% had TKR in the study knee, respectively. Use of ZA was associated with a higher risk of TKR in any knee (hazard ratio [HR] 4.2, 95% confidence interval [CI] 1.2-14.7) and showed a trend in the study knee (HR 6.8, 95%CI 0.9-53.9) during the trial. In the posttrial period, the risk of TKR was similar in the ZA and the placebo groups for any knee (HR 1.2, 95%CI 0.5-1.8) and the study knee (HR 1.4, 95%CI 0.5-2.2). CONCLUSION: These results suggest that ZA is not protective against TKR in patients with symptomatic knee osteoarthritis and without severe JSN.

A Polished Cobalt-Chrome Baseplate is not Associated With a Lower Revision Rate Than Matt Titanium in a Single Total Knee Arthroplasty Implant System With Identical Baseplate Design.

BACKGROUND: Polished baseplates were introduced into total knee arthroplasty (TKA) systems to reduce the incidence of backside wear. In 2004, a fixed-bearing knee arthroplasty system underwent a change in baseplate material from matt titanium to polished cobalt-chrome (CoCr) with the intention to reduce backside wear. Other design aspects were left unchanged. The aim of this study was to compare these implants with each baseplate using data from the Australian Orthopaedic Association National Joint Replacement Registry. METHODS: Primary TKA procedures performed between January 2010 and December 2021 for osteoarthritis, using a single design with cross-linked polyethylene inserts and matt titanium or polished CoCr baseplates, were analyzed. The primary outcome was all-cause revision, summarized using Kaplan-Meier estimates, with age- and sex-adjusted hazard ratios estimated from Cox proportional hazards models. In total, there were 2,091 procedures with matt titanium and 2,519 procedures with polished CoCr baseplates. RESULTS: The 9-year cumulative percent revision was 2.5% (95% confidence interval [CI] 1.8 to 3.5%) and 4.2% (95% CI 3.1 to 5.6%) for the matt titanium and CoCr groups, respectively. Compared to matt titanium, the revision rate of CoCr baseplates was not significantly higher (hazard ratio 1.44; 95% CI 0.96 to 2.15; P = .076). CONCLUSIONS: Polished CoCr baseplates in a single TKA system were not associated with reduced all-cause revision rates compared to matt titanium up to 11 years post-TKA. Our results suggest that the predicted reduction in wear particle debris production from polished CoCr baseplates may not correlate with reduced revision rates in vivo, but further evaluation is required.

Radiolucent line assessment in cemented stemmed total knee (RISK) arthroplasty: validation of a modernized classification system.

BACKGROUND: This study aims to implement and assess the inter- and intra-reliability of a modernized radiolucency assessment system; the Radiolucency In cemented Stemmed Knee (RISK) arthroplasty classification. Furthermore, we assessed the distribution of regions affected by radiolucency in patients undergoing stemmed cemented total knee arthroplasty. METHODS: Stemmed total knee arthroplasty cases over 7-year period at a single institution were retrospectively identified and reviewed. The RISK classification system identifies five zones in the femur and five zones in the tibia in both the anteroposterior (AP) and lateral planes. Post-operative and follow-up radiographs were scored for radiolucency by four blinded reviewers at two distinct time points four weeks apart. Reliability was assessed using the kappa statistic. A heat map was generated to demonstrate the reported regions of radiolucency. RESULTS: 29 cases (63 radiographs) of stemmed total knee arthroplasty were examined radiographically using the RISK classification system. Intra-reliability (0.83) and Inter-reliability (0.80) scores were both consistent with a strong level of agreement using the kappa scoring system. Radiolucency was more commonly associated with the tibial component (76.6%) compared to the femoral component (23.3%), and the tibial anterior-posterior (AP) region 1 (medial plateau) was the most affected (14.9%). CONCLUSION: The RISK classification system is a reliable assessment tool for evaluating radiolucency around stemmed total knee arthroplasty using defined zones on both AP and lateral radiographs. Zones of radiolucency identified in this study may be relevant to implant survival and corresponded well with zones of fixation, which may help inform future research.

Obesity is associated with an increased risk of undergoing hip replacement in Australia.

BACKGROUND: Obesity is a known risk factor for the development of hip osteoarthritis. The aim of this study was to investigate whether obesity is associated with the risk of undergoing total hip replacement (THR) in Australia. METHODS: A cohort study was conducted comparing data from the Australian Bureau of Statistics and the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) from 2017 to 2018. Body mass index (BMI) data for patients undergoing primary total hip replacement and resurfacing for osteoarthritis were obtained from the AOANJRR. The distribution of THR patients by BMI category was compared to the general population, in age and sex sub-groups. RESULTS: During the study period, 32 495 primary THR were performed for osteoarthritis in Australia. Compared to the general population, there was a higher prevalence of Class I, II and III obesity in patients undergoing THR in both sexes aged 35-74 years. Class III obese females and males aged 55-64 years were 2.9 and 1.7 times more likely to undergo THR, respectively (P < 0.001). Class III obese females and males underwent THR on average 5.7 and 7.0 years younger than their normal weight counterparts, respectively. CONCLUSION: Obese Australians are at increased risk of undergoing THR, and at a younger age.

Obesity is associated with an increased risk of undergoing knee replacement in Australia.

BACKGROUND: Obesity is associated with the development of knee osteoarthritis (OA). The aim of this study was to examine the incidence of obesity in patients undergoing knee replacement (KR) for OA in Australia compared to the incidence of obesity in the general population. METHODS: A cohort study was conducted, comparing data from the Australian Bureau of Statistics (ABS) 2017-2018 National Health Survey with data from the National Joint Replacement Registry. The distribution of patients who underwent KR from July 2017 to June 2018 by BMI category was compared to the distribution of the general population, in age and gender sub-groups. RESULTS: During the study period, 35.6% of Australian adults were overweight and 31.3% were obese. Of the 56 217 patients who underwent primary KR for OA, 31.9% were overweight and 57.7% were obese. The relative risk of undergoing KR for OA increased with increasing BMI category. Class 1, 2 and 3 obese females aged 55-64 years were 4.7, 8.4 and 17.3 times more likely to undergo KR than their normal weight counterparts, respectively. Males in the same age and BMI categories were 3.4, 4.5 and 5.8 times more likely to undergo KR, respectively. Class 3 obese patients underwent KR 7 years younger, on average, than normal weight individuals. CONCLUSION: Obesity is associated with an increased risk of undergoing KR, and at a younger age, particularly for females. There is an urgent need for a societal level approach to address the prevalence of obesity, to reduce the burden of obesity related KR.

Knee Arthroplasty Component Malrotation Does Not Affect Function or Quality of Life in the Short to Medium Term.

BACKGROUND: Component rotation in total knee arthroplasty is thought to affect patella tracking, flexion gap, and balancing and hence is hypothesized to affect function, pain, and longevity. Few studies have directly correlated post-operative component rotation to function and quality of life in the short to medium term post-operatively, with findings in the current literature conflicting. METHODS: A retrospective study of prospectively collected data was used to determine the effect of femoral, tibial, and combined component rotation in primary total knee arthroplasty with primary outcomes being function as measured by the Knee Society Score, pain and quality of life as measured by the Short-Form 12 score, and secondary outcome being prosthesis failure. Malrotation was defined using the current literature as being internally rotated from neutral, or externally rotated greater than 5° for the femoral component, internally rotated greater than 6° for the tibial component, or internally rotated from neutral for the 2 components combined. RESULTS: No clinically relevant correlation between function or quality of life and component rotation could be found at 5 years. However, it was noted that those patients with combined component malrotation (femoral rotation added to tibial rotation resulting in overall component internal rotation) improved less in overall pain scores than those that were not malrotated. CONCLUSION: In the mid-term, component malrotation may result in a decreased level of improvement from pain compared to pre-operative results. However, component malrotation does not make a significant difference to function or quality of life. LEVEL OF EVIDENCE: Level III: Therapeutic Study.

Gap Balancing Sacrifices Joint-Line Maintenance to Improve Gap Symmetry: 5-Year Follow-Up of a Randomized Controlled Trial.

BACKGROUND: Gap balancing (GB) has been noted to sacrifice joint-line maintenance to improve gap symmetry. This study aims to determine whether this change affects function or quality of life in the midterm. METHODS: A prospective blinded randomized controlled trial was completed with 103 patients randomized to measured resection (n = 52) or GB (n = 51). Primary outcome measured was femoral component rotation. Secondary outcomes measured were joint-line change, gap symmetry, and function and quality-of-life outcomes. RESULTS: At 5 years, 83 of 103 patients (85%) were assessed. There was no significant difference between groups in terms of functional or quality of life outcomes. A subgroup analysis revealed that there was no significant association between those with asymmetrical flexion and/or extension or medial and/or lateral gaps during knee replacement and subsequent functional outcomes. No significant difference was detected with those with an elevated joint line and postoperative function. CONCLUSION: In the midterm, the resultant change in joint-line and maintained gap symmetry noted with GB does not result in significant change to function or quality of life.

Gap balancing sacrifices joint-line maintenance to improve gap symmetry: a randomized controlled trial comparing gap balancing and measured resection.

A total knee arthroplasty can be completed using two techniques; measured resection or gap balancing. A prospective blinded randomized controlled trial was completed with 103 patients randomized to measured resection (n = 52) or gap balancing (n = 51). Primary outcome measure was femoral component rotation. Secondary outcome measures were joint-line change, gap symmetry and function and quality-of-life outcomes. Gap balancing resulted in a significantly raised joint-line compared to measured resection. Gap symmetry was significantly better using gap balancing. Functional outcomes and quality-of-life were not significantly different at 24 months. Using computer navigation, gap balancing significantly raises the joint-line in order to improve gap symmetry. This does not result in a clinical difference in function or quality of life at 24 months.

The long leg radiograph is a reliable method of assessing alignment when compared to computer-assisted navigation and computer tomography.

BACKGROUND: The mechanical alignment of the knee is an important factor in planning for, and subsequently assessing the success of a knee replacement. It is most commonly measured using a long-leg anteroposterior radiograph (LLR) encompassing the hip, knee and ankle. Other modalities of measuring alignment include computer tomography (CT) and intra-operative computer navigation (Cas). Recent studies comparing LLRs to Cas in measuring alignment have shown significant differences between the two and have hypothesized that Cas is a more accurate modality. This study aims to investigate the accuracy of the above mentioned modalities. METHODOLOGY: A prospective study was undertaken comparing alignment as measured by long-leg radiographs and computer tomography to intra-operative navigation measurements in 40 patients undergoing a primary total knee replacement to test this hypothesis. Alignment was measured three times by three observers. Intra- and inter-observer correlation was sought between modalities. RESULTS: Intra-observer correlation was excellent in all cases (>0.98) with a coefficient of repeatability <1.1°. Inter-observer correlation was also excellent measuring >0.960 using LLRs and >0.970 using CT with coefficient of repeatability <2.8°. Inter-modality correlation proved to be higher when comparing LLRs and CT (>0.893), than when comparing either of these modalities with Cas (>0.643 and >0.671 respectively). Pre-operative values had the greatest variability. CONCLUSION: Given its availability and reduced radiation dose when compared to CT, LLRs should remain the mainstay of measuring the mechanical alignment of the lower limb, especially post-operatively. LEVEL OF EVIDENCE: II.

The effect of tibio-femoral over-distraction in primary knee arthroplasty.

PURPOSE: Overstuffing the patellofemoral joint has been associated with poor post-operative outcomes. No study has assessed the effect of over-distracting the tibio-femoral joint in the vertical plane and its effects on function and quality of life. The purpose of this study is to assess the effect of tibio-femoral joint distraction on function and quality of life after total knee arthroplasty. METHODS: Measurements of knee joint distraction were devised using long-leg alignment radiographs. Seventy-three patients were prospectively recruited and their joint distraction measured post-operatively. A comparison was made between the level of joint distraction and functional outcomes as measured by the International Knee Society score and its components, such as pain and flexion, and the Knee injury and Osteoarthritis Outcome Score and quality of life as measured by the Short-Form 12 score. Twelve-month follow-up was achieved. RESULTS: Knee joint over-distraction post-arthroplasty correlated significantly with Knee Society score (p = 0.041), flexion (p = 0.005) and pain (p = 0.002). Those knees that were over-distracted post-operatively suffered more pain, less flexion and a lower International Knee Society score compared with their counterparts. No correlation was found between over-distracting the knee joint and quality of life. CONCLUSION: Over-distracting the tibio-femoral joint during arthroplasty is a significant predictor of reduction in function and increase in pain in the short to medium term. When between sizes of tibial inserts, the surgeon should consider using the thinner option.

Coronal alignment correlates with outcome after total knee arthroplasty: five-year follow-up of a randomized controlled trial.

In a prospective randomized control trial comparing computer-assisted vs conventional total knee arthroplasty, we previously reported that patients with coronal alignment within 3° of neutral had superior international knee society and Short-Form 12 (SF-12) physical scores at 6 weeks, 3 months, 6 months, and 12 months after surgery. Computer-assisted total knee arthroplasty achieved greater accuracy in implant alignment, and this correlated with better knee function and quality of life. At 5 years, 90 of 111 patients assessed in our original study were reviewed. Coronal alignment within 3° of neutral continued to be correlated with superior International Knee Society and SF-12 scores. Coronal alignment greater than 3° was associated with a significant decline in SF-12 mental health scores.

The impact of obesity on weight change and outcomes at 12 months in patients undergoing total hip arthroplasty.

OBJECTIVES: To establish the rate of clinically significant weight change after 12 months in patients who have had a primary total hip arthroplasty (THA); to identify patient characteristics that predicted weight loss or gain; and to compare clinical and functional outcomes between obese and non-obese patients. DESIGN, SETTING AND PARTICIPANTS: Prospective study of 471 patients who underwent THA between 2006 and 2007 at St Vincent's Hospital, Melbourne, a university-affiliated tertiary referral centre. Patients were classified as non-obese, obese and morbidly obese, and were assessed using the Harris Hip Score (HHS) and 12-item Short Form Health Survey (SF-12). MAIN OUTCOME MEASURES: Incidence of weight loss or gain 12 months after surgery; preoperative patient variables predictive of weight change; functional and quality-of-life outcomes and rate of adverse events at 12 months; differences in outcomes between obese and non-obese patients. RESULTS: 194 patients (41%) were obese or morbidly obese. At 12-month follow-up, 18 obese or morbidly obese patients (9%) had lost >or= 5% of their preoperative weight and 118 patients (25%) had gained >or= 5% of their preoperative weight. No preoperative predictor of weight loss was identified, but weight gain was associated with lower preoperative SF-12 mental health scores (odds ratio [OR], 0.98 [95% CI, 0.96-0.99]; P = 0.04). There were no significant differences between obesity groups in improvement in HHS or SF-12 physical health scores. Improvement in SF-12 mental health scores was greater in obese (+ 3.6 [SD, 12.2]) and morbidly obese (+ 3.7 [SD, 9.4]) patients than in non-obese patients (- 0.1 [SD, 11.7]) (P = 0.01). Compared with non-obese patients, the odds of a postoperative complication were significantly greater in obese patients (OR, 1.81 [95% CI, 1.05-3.11]) and morbidly obese patients (OR, 5.77 [95% CI, 2.10-15.86]). CONCLUSION: Clinically significant weight loss in obese patients after THA is uncommon. Obese and morbidly obese patients experience comparable reduction in pain and improvement in function after THA, but the risk of complications in the first 12 months after surgery is significantly greater than the risk in non-obese patients.

The need for patellar resurfacing in total knee arthroplasty: a literature review.

The controversy over whether or not to routinely resurface the patella during a total knee arthroplasty has persisted despite three decades of successful joint replacement procedures. Advocates for routine patellar resurfacing admit the occasional need for secondary patellar resurfacing and declare increased incidence of anterior knee pain in patients with non-resurfaced patellae as a cause for worry. Surgeons that leave the patella unresurfaced cite avoidance of complications that include patellar fracture, avascular necrosis, patellar tendon injury and instability. This review discusses the available literature on patellar resurfacing through an evidence-based analysis of randomized and pseudo-randomized controlled trials and published meta-analyses to date. The published literature seems to favour resurfacing the patellar routinely. Selective patellar resurfacing would be the ideal solution if sound pre-operative criteria could be established. So far, a method for accurately predicting which patients can avoid patellar resurfacing has not been found. Future research looking at patellar resurfacing should concentrate on developing criteria for selecting those patients that would benefit from patellar resurfacing and those that would do as well without resurfacing, and thus, limiting potential surgical complications.

Arthroplasty of a Charcot knee.

The Charcot knee - or neuropathic arthropathy - presents a considerable challenge to the orthopaedic surgeon. Caused by a combination of sensory, motor and autonomic neuropathy, it was originally described as an arthritic sequelae of neurosyphilis. In today's western orthopaedics it is more often caused by diabetes. A Charcot knee is often symptomatically painful and unstable. Traditional management has usually been conservative or arthrodesis, with limited success. Arthroplasty of a Charcot joint has commonly been avoided at all costs. However, in the right patient, using the right technique, arthroplasty can significantly improve the symptoms of a Charcot joint. This article explores the evidence surrounding the role of arthroplasty in the management of a Charcot knee. Arthroplasty is compared to other forms of treatment and specific patient demographics and surgical techniques are explored in an attempt to define the role of arthroplasty in the management of a Charcot knee.

Periprosthetic bone remodeling using a triple-taper polished cemented stem in total hip arthroplasty.

The triple-taper cemented femoral stem was developed to promote proximal femoral and calcar loading to minimize periprosthetic bone loss and aseptic loosening. Periprosthetic changes in bone mineral density in Gruen zones 1 to 7 were analyzed in 103 patients over a 2-year period using dual x-ray absorptiometry. There was a statistically significant decrease in bone mineral density in all Gruen zones, but was most marked in zones 1 and 7. Periprosthetic bone density was reduced significantly in the first 3 to 9 months, after which recovery of bone density occurred. Greater calcar bone loss was seen in women, patients with a low preoperative bone density, and patients with poor postoperative mobility. Age at surgery did not effect calcar bone loss.

Does accurate anatomical alignment result in better function and quality of life? Comparing conventional and computer-assisted total knee arthroplasty.

This is a randomized prospective controlled trial comparing the alignment, function, and patient quality-of-life outcomes between patients undergoing conventional (CONV) and computer-assisted (CAS) knee arthroplasty. One hundred and fifteen patients (60 CAS, 55 CONV) underwent cemented total knee arthroplasty. Three patients were lost to follow-up. Eighty-eight percent (CAS) vs 61% (CONV) of knees achieved a mechanical axis within 3 degrees of neutral (P = .003). Aligning femoral rotation with the epicondylar axis was accurately achieved in CAS and CONV with no significant difference. Patients with coronal alignment within 3 degrees of neutral had superior International Knee Society and Short-Form 12 physical scores at 6 weeks, 3 months, 6 months, and 12 months after surgery. Computer-assisted total knee arthroplasty achieves greater accuracy in implant alignment and this correlates with better knee function and improved quality of life.

The relevance of ligament balancing in total knee arthroplasty: how important is it? A systematic review of the literature.

Ligament balancing affects many of the postoperative criteria for a successful knee replacement. A balanced knee contributes to improved alignment and stability. Ligament balancing helps reduce wear and loosening of the joint. A patient with a balanced knee is more likely to have increased range of motion and proprioception, and decreased pain. All these factors help minimize the need for revision surgery. Complications associated with ligament balancing can include instability caused by over-balancing and the possibility of neurovascular damage during or as a result of ligament balancing. This article attempts to summarize the literature, to define a balanced knee, and outline the benefits and possible complications of ligament balancing. Different techniques, sequences, and tools used in ligament balancing, and their relevance in correcting various deformities are reviewed.

Outcomes of total knee arthroplasty in English- versus non-English-speaking patients.

PURPOSE: To compare outcomes of total knee arthroplasty (TKA) in English- versus non-English-speaking patients. METHODS: 193 women and 85 men (mean age, 72 years) underwent 117 left and 161 right primary TKAs. 237 and 41 patients were English and non-English speaking, respectively. Interpretation was provided. Pre- and post-operative functional outcomes were measured using the International Knee Society (IKS) score. RESULTS: Most non-English-speaking patients were female (38 vs 3 of 41, p<0.001). The mean body mass index of non-English-speaking patients was significantly higher (34 vs 31 kg/m[2], p=0.003). 14 foreign languages were spoken among the 41 non-English-speaking patients, of which Greek and Italian were the most common. Non-English-speaking patients had significantly worse IKS scores both preoperatively and at the 12-month follow-up. The proportions of poor postoperative IKS scores were significantly higher in non-English-speaking patients (58% vs 27%, p<0.001), in whom pain was also significantly worse (p=0.017). In a multiple logistic regression analysis, being non-English speaking was the only predictor of poor functional outcome at the 12-month follow-up (odds ratio=2.77, confidence interval=1.25-6.14, p=0.012). CONCLUSION: The non-English-speaking background of a patient is a predictor of less favourable functional outcome after TKA.