Does Implant Design Influence Failure Rate of Lateral Unicompartmental Knee Arthroplasty? A Meta-Analysis

Long-Term Outcomes in Unicompartmental Knee Arthroplasty: Survivorship of Medial versus Lateral Unicompartmental Knee Arthroplasty

Unicompartmental knee arthroplasties (UKAs) currently represent an important portion of knee arthroplasty procedures and their usage is on an upward trend. Despite offering better functional outcomes and a quicker recovery compared to total knee arthroplasties (TKAs), UKAs are often scrutinized for their longevity. This article provides an in-depth examination of the technical nuances and survival rates of medial versus lateral UKAs, drawing on recent advances and findings in the field. This manuscript thoroughly evaluates the comparability of patient populations undergoing medial and lateral UKAs, considering their anatomical, biomechanical, and demographic differences. It delves into the specific technical challenges associated with each type and systematically assesses the factors that influence failure, including the intricacies of implant design and patient-specific variables. Despite relevant anatomical and biomechanical contrasts between medial and lateral UKAs, recent literature points to comparable survival rates. The prevalence of early failures within the initial five years post-operation underscores the criticality of precise patient selection and refined surgical techniques. The paper succinctly summarizes pivotal literature and provides essential guidance for optimizing UKA survivorship. It underscores the importance of meticulous patient selection and precise surgical techniques, alongside the identification and mitigation of potential pitfalls that impact outcomes. Finally, robotic technology in UKA has considerably enhanced the precision and reproducibility, representing a viable solution to effectively meet and achieve the recommended technical objectives.

Lateral unicompartmental knee arthroplasty: is really a good option?

INTRODUCTION

Lateral unicompartmental knee arthroplasties (LUKA) account for only < 1% of all knee arthroplasties and for only 5-10% of all unicompartmental knee replacements. This means that there is less published literature on these procedures and that the surgeon's experience with them is smaller than with medial UKA. The aim of this study was to analyze the survival and the clinical-functional outcomes of LUKA according to the type of bearing surface (all-polyethylene versus metal-backed) used.

MATERIALS AND METHODS

This was a retrospective study including 42 LUKAs operated between 2009 and 2021. Two fixed polyethylene-bearing models were used: the all-polyethylene ACCURIS knee (38%) and the metal-backed Triathlon PKR system (62%). Demographic parameters, knee range of motion (ROM), tibiofemoral alignment, implant survival (as estimated with the Kaplan-Meier curve), and clinical-functional outcomes (as measured with the Knee Society Score) were analyzed.

RESULTS

Average patient age was 65.5 (range, 36-87) years and mean follow-up was 8.2 (range, 2.1-12.8) years. Thirty LUKAs (71.4%) were implanted in women. The main reason for performing a LUKA was osteoarthritis (88.1%). No patient developed post-surgical complications or had to be re-operated. Overall LUKA survival was 100% at 1-year and 5-year's follow-up. Knee Society Score, knee ROM and tibiofemoral alignment all improved significantly post-surgery (p < 0.001). The clinical Knee Society Score increased from 46.5 ± 14.5 pre-surgery to 93.5 ± 10.3 post-surgery, the functional Knee Society Score increased from 48.1 ± 13.5 pre-surgery to 94.6 ± 9.3 post-surgery, maximum flexion increased from 108.5 ± 8.7 degrees pre-surgery to 121 ± 8.9 degrees post-surgery and tibiofemoral alignment was corrected from 13.1 ± 1.74 degrees pre-surgery to 5.7 ± 0.8 degrees post-surgery. There were no statistically significant clinical-functional improvement or knee ROM differences between groups (p < 0.05, respectively).

CONCLUSION

LUKA is a valid and definitive option for patients with lateral tibiofemoral osteoarthritis, with a survival rate of > 95% at 5-years follow-up. Clinical-functional outcomes are the same, irrespective of the tibial component used.

All-Polyethylene Tibial Component in Unicompartmental Knee Arthroplasty Offers Excellent Survivorship and Clinical Outcomes at Short-Term Follow-Up: A Multicenter Retrospective Clinical Study

Background and Objectives: The ten-year survivorship of unicompartmental knee arthroplasty (UKA) is up to 96%, varying from implants and hospitals; however, most of registry studies do not distinguish between metal-back (MB) tibial implants and all-polyethylene (AP) tibial implants. The aim of the present retrospective clinical study was to analyze the clinical outcomes and survivorship of medial and lateral UKA with a newly designed all-polyethylene tibial plateau at short-term follow-up. Materials and Methods: A retrospective analysis of prospectively collected consecutive patients who underwent medial or lateral UKA with AP tibial plateau was conducted, with a minimum follow-up of 1 year. Primary outcomes were clinical score (VAS, OKS, and KOOS) variations from baseline up to the latest follow-up. Secondary outcomes were Likert scale variations from baseline to the follow-up, evaluation of the influence of demographic factors (age and BMI) at the time of surgery on the clinical outcomes, and evaluation of revision rate up to the last follow-up. Results: The final study population included 99 knees. The mean VAS score for the medial group significantly decreased from 7.61 ± 1.65 (pre-intervention) to 2.74 ± 2.26 (post-intervention). Similar improvements were registered for the OKS as well, for both the medial group (from 22.5 ± 12.6 to 36.6 ± 10.6, with a delta of 14.11 (10.05 to 18.17)) and the lateral group (from 22.6 ± 12.6 to 36.9 ± 11.8, with a delta of 14.24 (8.65 to 19.83)). Moreover, all the KOOS subscales reported an amelioration, both in medial UKA and lateral UKA. Furthermore, a logistic regression of delta VAS was performed in relation to the other clinical questionnaires and the demographic factors. For both medial and lateral UKAs, no statistically significant correlation was found between the VAS scale regression and the demographic factors. The survival rate free from any revision of the cohort at the latest follow-up was 96.32%. Conclusions: All-polyethylene tibial component in unicompartmental knee arthroplasty demonstrates significant improvements in clinical scores and a low failure rate at short-term follow-up.

Lateral Unicompartmental Knee Arthroplasty for Osteoarthritis Secondary to Lateral Meniscectomy: High Functional Results and Survivorship and Low Osteoarthritis Progression at a Mean 10 Years of Follow-up

BACKGROUND

Meniscectomy, whether partial or total, is a common knee surgery, but it considerably increases the risk of knee osteoarthritis (OA). Lateral meniscectomy has more severe consequences than medial meniscectomy, leading to faster OA progression and worse clinical outcomes. Unicompartmental knee arthroplasty (UKA) is a suitable treatment option for lateral OA and has demonstrated better outcomes than total knee arthroplasty (TKA). The aims of this study were to evaluate the clinical and functional results, OA progression in the medial compartment, and implant survivorship following lateral UKA in patients with OA secondary to lateral meniscectomy and to compare these outcomes with those of patients who underwent lateral UKA for primary lateral OA.

METHODS

Between 2001 and 2017, 214 lateral UKAs were performed. Of these, 42 were performed for OA secondary to lateral meniscectomy. The control group was composed of patients who underwent lateral UKA for primary lateral OA and was formed through a 1:1 case-control matching process based on sex, age, body mass index, and operation date. The outcomes that were studied included range of motion, Knee Society Score, University of California Los Angeles (UCLA) Activity Score, Tegner Activity Scale, Forgotten Joint Score, visual analog scale for pain, OA progression in the medial compartment, and implant survivorship.

RESULTS

At a mean follow-up of 10.2 years, both groups demonstrated significant improvements (p < 0.01) after lateral UKA in all clinical and functional scores except the UCLA Activity Score and Tegner Activity Scale. No significant differences in clinical and functional scores were found between the groups. However, patients with OA secondary to meniscectomy exhibited significantly less OA progression in the medial compartment (p = 0.035) and higher 10-year implant survival (97.6% versus 83.3%).

CONCLUSIONS

Lateral UKA is an effective treatment option for OA secondary to lateral meniscectomy, providing excellent functional outcomes and survivorship. Patients with post-meniscectomy OA exhibited less OA progression in the medial compartment than patients with primary OA and, consequently, had better 10-year implant survivorship.

LEVEL OF EVIDENCE

Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Short- to mid-term results of minimally invasive lateral unicompartmental knee replacement: 133 cases in a non-designer series

INTRODUCTION

The aim of the current study was to demonstrate short- to mid-term survivorship as well as clinical outcome of lateral unicompartmental knee replacement (UKR) with a fixed-bearing (FB) design from a non-designer center using the Oxford Fixed Lateral prosthesis.

MATERIALS AND METHODS

This single-center retrospective cohort study reports the results of 133 consecutive lateral FB-UKR. Survivorship analysis was performed with different endpoints and clinical outcome was measured using the Oxford-Knee-Score (OKS), American-Knee-Society-Score (AKSS-O), range-of-motion (ROM) and visual-analog-scale for pain (VAS).

RESULTS

There were two revision surgeries with conversion to total knee replacements (TKR) due to persistent pain resulting in a survival rate of 98.5% (95% CI 93.5-99.6) with a mean follow-up (FU) of 3.3 ± 1.8 years (range 1-8.5). All outcome scores, VAS and ROM showed a significant improvement at final FU (p < 0.001). The OKS improved from 26 ± 7.8 (range 11-45) preoperatively to 39 ± 8.3 (range 13-48), the AKSS-O from 49.2 ± 14.6 (range 18-90) to 81.8 ± 15.1 (range 40-100), the AKSS-F from 53 ± 23.7 (range 0-100) to 80.4 ± 21.4 (range 5-100) and the ROM from 118 ± 17 (range 90-160) to 134 ± 9.5 (range 100-155).

CONCLUSIONS

The short- to mid-term results following lateral FB-UKR demonstrate a high survivorship and good clinical outcome from an independent series. We, therefore, suggest that FB-UKR is a safe treatment option for isolated lateral OA if sufficient surgical experience is provided.

LEVEL OF EVIDENCE

Retrospective cohort study, level IV.

Mild Valgus Alignment After Lateral Unicompartmental Knee Arthroplasty Led to Lower Functional Results and Survivorship at Mean 8-Year Follow-Up

BACKGROUND

In medial unicompartmental knee arthroplasty (UKA), the best results and the highest survivorship are found by mild undercorrection of varus deformities. In lateral UKA, the desirable amount of valgus undercorrection has not yet been determined. The purposes of this study were to present the results of a consecutive series of lateral UKAs and to investigate the effect of postoperative limb alignment on them.

METHODS

A total of 161 lateral UKA were reviewed. Outcomes studied included range of motion (ROM), Knee Society Score (KSS), University of California Los Angeles Activity Score, Tegner Activity Scale, Forgotten Joint Score, visual analogue scale (VAS) for pain, and survivorship. Patients were divided into two groups according to postoperative alignment: group A (hip-knee-ankle ≥184°, 79 UKA) and group B (hip-knee-ankle <184°, 82 UKA).

RESULTS

At a mean follow-up of 8 years (range, 2-18), ROM (P < .01); KSS-C (P < .01); KSS-F (P < .01); VAS (P < .01) improved from baseline. No differences were noted in postoperative ROM, VAS, University of California Los Angeles, Tegner Activity Scale, and Forgotten Joint Score between groups. Group A showed higher postoperative clinical and functional KSS (P < .01) and higher survivorship (96.2 versus 91.5%, P = .01) than group B.

CONCLUSION

Mild valgus alignment (3° or less) after lateral UKA is linked to lower clinical and functional scores and lower survivorship compared to moderate valgus (over 4°) at mean 8-year follow-up. More undercorrection of the coronal deformity in lateral UKA compared to medial UKA is desirable to get the best results.

Total knee arthroplasty improves sports activity and the patient-reported functional outcome at mid-term follow-up

PURPOSE

The purpose of this study was to assess (1) sports participation and preference for the type of sports activity after TKA, (2) mid-term functional outcome and activity level, (3) correlation of different age groups with activity level and functional outcomes, and (4) mid-term survivorship of the prosthesis.

METHODS

A retrospective review of prospectively collected data was performed. 182 patients were included who underwent primary TKA between January 2010 and December 2016. Inclusion criteria were symptomatic knee osteoarthritis, age 50-90 years, and with a minimum of 5-year follow-up after TKA. Patients with rheumatoid arthritis and revision TKA were excluded. Sports participation and sports preference, Oxford Knee Score (OKS), Tegner Activity Level, and Visual Analogue Scale (VAS) for pain were recorded pre- and postoperatively at 6 months, 1 year, 2 years, and 5 years. The patient cohort was subdivided according to age groups; activity levels, patient-reported outcomes, and improvement in knee pain were correlated with these age groups. Kaplan-Meier curves were used to investigate survivorship at a minimum of 5 years.

RESULTS

The mean age of the cohort was 75.6 ± 7.2 years (range 52-89). Significant improvement was noted in sports participation (p < 0.003). After TKA, there was no change in the preference for sports and none of the patients had to discontinue their sporting activity. OKS improved significantly at all follow-up time points compared to the preoperative score (p < .0001). Patients' sports and physical activity improved significantly at 1 year compared to the preoperative activity level (p < 0.001). Although the Tegner activity level improved over time, this improvement was not significant (NS), while it was significantly higher in males than in females (p < 0.004). Significant improvement was found in the VAS for pain at all follow-up time points compared to the preoperative score (p < .0001). Survivorship was found to be 100% at a 5-year follow-up.

CONCLUSION

After TKA, patients can be able to return to sporting activity or even perform better than before surgery. Maximum improvement was noted in the first post-operative year. The male and younger groups perform better than the female and older groups. Sports and physical activity do not negatively impact survivorship of the knee prosthesis at mid-term follow-up and all patients are encouraged to take up sports participation after their TKA.

LEVEL OF EVIDENCE

Level 3.

Complications and downsides of the robotic total knee arthroplasty: a systematic review

PURPOSE

The purpose of this systematic review is to describe the complications and downsides of robotic systems in total knee arthroplasty (TKA).

METHODS

A comprehensive search according to the PRISMA guidelines was performed across PubMed, MEDLINE, Cochrane Central Register of Controlled Trials, Scopus, and Google Scholar from inception until December 2021. All articles of any study design directly reporting on complications and downsides of the robotic system in TKA were considered for inclusion. Risk of bias assessment was performed for all included studies using the Cochrane risk of bias and MINORS score.

RESULTS

A total of 21 studies were included, consisting of 4 randomized controlled trials, 7 prospective studies and 10 retrospective studies. Complications of the robotic system were pin-hole fracture, pin-related infection, iatrogenic soft tissue and bony injury, and excessive blood loss. While, downsides were longer operative duration, higher intraoperative cost, learning curve and aborting a robotic TKA due to different reasons. Iatrogenic injuries were more common in the active robotic system and abortion of the robotic TKA was reported only with active robotic TKA.

CONCLUSION

Robotic TKA is associated with certain advantages and disadvantages. Therefore, surgeons need to be familiar with the system to use it effectively. Widespread adoption of the robotic system should always be evidence-based.

LEVEL OF EVIDENCE

IV.

No difference in sports participation and patient-reported functional outcomes between total knee arthroplasty and unicompartmental knee arthroplasty at minimum 2-year follow-up in a matched control study

PURPOSE

The purpose of this study was to compare (1) sports participation and type of sports activity between TKA and UKA patients; (2) functional outcome and activity level between TKA and UKA; and (3) survivorship of the prosthesis in both the groups.

METHODS

Prospectively collected data were obtained from an arthroplasty database to identify patients who underwent primary TKA and UKA. Both the cohorts of TKA and UKA were matched, controlling for age, sex, BMI and preoperative patient-reported outcomes, which include Oxford Knee Score (OKS), Tegner activity level, and visual analog scale (VAS) for pain score. After matching the two groups, 287 TKA and 69 UKA cases were available to be included in the study. Patients were evaluated pre- and postoperatively at 2 years for sports participation and sports preference, patient-reported outcomes, activity levels, and improvement in knee pain.

RESULTS

The mean age of the TKA and UKA groups were 75.7 ± 8.1 and 74.2 ± 8.8, respectively. There was no significant difference between the two groups concerning the demographic variables. Significant improvement was noted in the weekly sports participation at the final follow-up compared to preoperative sports participation in both the TKA and UKA groups (p < 0.05). All patients were able to return to their desired sporting activity. No significant difference was noted between the two groups in sports participation preoperatively and postoperatively (p > 0.05). OKS, Tegner activity level and VAS for pain demonstrated a significant improvement from preoperative to 2 years postoperatively (p < 0.05). However, preoperative and postoperative patient-reported outcomes did not differ significantly between the TKA and UKA groups (p > 0.05). No case of revision surgery was found at a 2-year follow-up in both groups.

CONCLUSION

Traditionally, in isolated medial compartment osteoarthritis, UKA has been considered to be the procedure with better functional outcomes, but the current study demonstrates that when confounding factors are controlled, both TKA and UKA are effective, and offer similar functional outcomes and result in similar improvement in sports participation. These findings will be helpful to counsel the patients to choose the best suitable operative procedure between UKA and TKA.

LEVEL OF EVIDENCE

Level 3.

Safety and Efficacy of Unicondylar Knee Prosthesis Treatment for Unicompartmental Osteoarthritis of the Knee Joint

Background

Knee osteoarthritis (KOA) is a chronic disease that seriously endangers the health of the elderly. Choosing appropriate surgery for knee osteoarthritis patients is especially important.

Objective

To investigate the safety and efficacy of unicondylar knee prosthesis treatment for unicompartmental osteoarthritis of the knee.

Materials and Methods

One hundred patients with unicondylar osteoarthritis of the knee treated in our hospital from June 2019 to June 2021 were selected as retrospective study subjects and were divided into 50 cases each in the comparison group and the observation group according to the different surgical methods. Among them, the comparison group was treated with unicondylar knee arthroplasty (UKA), and the observation group was treated with unicondylar knee prosthesis replacement, and the differences in AKS score, knee flexion angle, tibial angle orthosis, joint mobility, and postoperative recovery were compared between the two groups.

Results

The AKS score and knee flexion angle score of the observation group were higher than those of the comparison group after surgery. However, the tibial angle orthopedic score of the observation group was significantly lower than that of the comparison group after surgery for comparison, and the VAS score of the observation group was lower than that of the comparison group. However, the Lysholm score of the observation group was higher than that of the control group after surgery (P < 0.05). The complication rate of patients in the observation group was significantly lower than that of the comparison group, and the HSS score, VAS score, and knee mobility (ROM) of the two groups were statistically significant (P < 0.05) when compared at 7 d after surgery and 6 months after surgery.

Conclusion

The clinical efficacy of unicondylar knee prosthesis replacement for osteoarthritis of the knee is better than that of unicondylar knee arthroplasty (UKA) treatment.