Minimum Five Years Follow-Up of Total Knee Arthroplasty Using Morphometric Implants in Patients With Osteoarthritis

A morphometric medial compartment-specific unicompartmental knee system: 5 years follow up results from a pilot center

BACKGROUND

Unicompartmental Knee Arthroplasty (UKA) is a valuable solution for the treatment of medial osteoarthritis of the knee. New implants feature designs for the elective substitution of a specific compartment. Aim of this study was to assess the survivorship and functional outcomes at minimum 4 years of the first 60 implanted patients in a pilot center of a new medial UKA as the evolution of a well performing long lasting fixed bearing implant.

METHODS

Between June 2017 and the end of 2018, 60 medial UKA were implanted in 58 patients. All patients were available for the last follow up and were analyzed prospectively. 37 were females and 21 were males with a mean age of 67 years (SD 10,71) and a mean of BMI 27.16 (SD 3.94) for the male population and of 26.73 (SD 4.05) for the female population.

RESULTS

At final follow up the mean Oxford Knee Score (OKS) was 44,02 (SD 3,1) and the mean Forgotten Joint Score (FJS) 78,6 (SD 7,9). The Knee Society Score (KSS) score was 95,2 for the "knee" score and 89.8 for the "function" score. No patients were revised. Kaplan-Meyer survival estimate showed a 100% survivorship at final follow up. No progressive radiolucent lines were found and no direct or indirect signs of polyethylene wear were registered on the final radiographs.

CONCLUSIONS

This new implant demonstrated promising clinical results with an excellent survival rate at short to midterm follow- up. Further follow up is needed to confirm this trend at longer term.

Early- to Mid-Term Review of a Prospective, Multi-Center, International, Outcomes Study of an Anatomically Designed Implant with Posterior-Stabilized Bearing in Total Knee Arthroplasty

Background and Objectives: National joint registries report higher total knee arthroplasty (TKA) revision rates in posterior-stabilized (PS) systems compared to non-posterior-stabilized designs. The purpose of this study was to investigate the implant survivorship and clinical outcomes of an anatomic implant with a PS bearing. Materials and Methods: An early- to mid-term follow-up of a prospective, multi-center, non-controlled outcomes study of patients who received primary TKA between November 2014 and June 2017 was performed. A total of 800 cases using PS bearings that were implanted in 664 patients were monitored post-operatively for their implant survivorship and adverse events for up to five years. The Knee Society Knee and Function scores, patient satisfaction, the five-dimensional European Quality of Life questionnaire, and range of motion (ROM) were evaluated pre-operatively and post-operatively at six weeks, six months, one year, two years, three years, and five years. Results: The mean follow-up period was 3.7 ± 1.3 years, and the three-year implant survival rate was 99.3% (95% CI: 98.4%, 99.7%) with five revisions during the five-year follow-up. Patient satisfaction was 96.1% at six weeks and increased to 99.3% at one year. All patient-reported outcome measures significantly (p < 0.0001) increased up to the one-year follow-up and then remained stable up to the five-year follow-up. Conclusions: This study supports the excellent survivorship and patient-reported outcomes of the Persona® Knee system using cemented, fixed bearing, posterior-stabilized components with minimal complications at early- to mid-term follow-up in an international Asian population. Ongoing observations are being performed to investigate the mid- to long-term survivorship and clinical outcomes associated with this knee system.

Total knee arthroplasty: do newer CR implants yield better results? A single center prospective study

The aim of this study was to compare whether the newest TKA prosthesis (Persona) gives improved clinical outcomes due its more anatomical design in comparison to older prostheses (balanSys). This study included a total of 89 patients planned for TKA from June 2018 to September 2019. Outcomes such as Knee Injury and Osteoarthritis Outcome Score (KOOS), range of motion (ROM), numeric pain rating scale (NRS), analgesics and alignment were recorded next to patient characteristics and complications. Our results showed a significant improvement in NRS, ROM and functional scores postoperatively compared to preoperatively for both the Persona and the balanSys implants. Although the flexion ROM for the Persona group was higher at 6 and 12 months postoperative compared to the balanSys, this was mainly a regaining of the preoperative ROM. Throughout all timepoints, there were no statistically significant differences observed in NSAID and opioid usage between the balanSys and Persona groups. Both implants are safe and efficient to use in the treatment of knee osteoarthritis. Although Persona had an improved postoperative flexion, this did not have an impact on any of the patient-reported outcomes.

Does Matching Femoral Size and Shape Improve Bone Fit and Patient-reported Outcomes in TKA? A Matched Controlled Study

BACKGROUND

Some researchers have suggested that achieving good component coverage over the host bone during TKA (while avoiding implant overhang) may help achieve durable implant fixation and may be associated with better outcomes scores. However, the evidence about this is limited and contradictory. Contemporary morphometric TKA includes a wide array of components with various shapes and sizes, based on large anatomic databases and specific software that simulates bone cuts. Morphometric tibial components have shown improved bone coverage and better clinical outcomes than standardized implants, but the role of morphometric femoral components in bone coverage has not been studied precisely.

QUESTIONS/PURPOSES

In a retrospective, controlled study that used patient matching, we asked: (1) Does the use of a contemporary morphometric component with more available sizes provide better femoral component fit and bone coverage than an earlier design with fewer sizes? (2) Are component fit and the presence of component overhang or underhang associated with different Knee Society Score (KSS) or Knee Injury and Osteoarthritis Outcome Score (KOOS) for Joint Replacement?

METHODS

From 2012 to 2013, we performed 403 TKAs according to the following criteria: TKA performed for primary tricompartmental arthritis of the knee; varus, valgus, and flexion deformity less than 15°; and age between 18 and 85 years on the day of surgery. Among these 403 TKAs, 237 were performed using a morphometric implant and 166 with the earlier nonmorphometric implant. At 2 years of follow-up, 3% of patients in the morphometric group and 5% in the nonmorphometric group were lost to follow-up. Based on age, BMI, gender, and preoperative KSS and KOOS, two groups of 30 patients were matched in a 1:1 ratio from this longitudinally maintained database. Clinical outcomes were measured preoperatively and at a minimum follow-up of 2 years in both groups, using the KSS and KOOS. We evaluated postoperative CT images for each patient to analyze femoral implant rotation, bone coverage, and overhang and underhang status.

RESULTS

The overhang status was similar between the two groups (23% had an overhang component in the morphometric knee group and 27% had an overhang component in the nonmorphometric knee group), and overhang was most frequently found in the lateral distal zone and medial anterior chamfer. Better cortical bone coverage was found in the morphometric knee group, with a thinner bone margin between the component edge and cortical border (morphometric group: 3 mm versus nonmorphometric knee group: 5 mm; p = 0.01). In general, there were few between-group differences in terms of patient-reported outcomes; of the seven metrics we analyzed, only the KSS favored the morphometric knee implant by a margin larger than the minimum clinically important difference (KSS mean difference: 21 points for the morphometric knee group; p < 0.05). Overhang of the femoral component of > 2 mm was associated with poorer KOOS, but not KSS, whereas a thinner bone margin had a beneficial impact on pain and global clinical scores (KOOS and KSS: p < 0.05).

CONCLUSION

The use of a morphometric femoral component design showed slightly improved bone fit and pain score according to the KSS at midterm follow-up compared with earlier implants with fewer sizes. Overhang > 2 mm was associated with worse KOOS. The tendency toward better outcomes in morphometric implants warrants longer-term evaluation before any definite conclusions about the association between bone fit and clinical results can be drawn.Level of Evidence Level III, therapeutic study.

Is sequential bilateral robotic total knee arthroplasty a safe procedure? A matched comparative pilot study

INTRODUCTION

To our knowledge, no papers have reported the results of robotic-assisted surgery for sequential bilateral Total Knee Arthroplasty (TKA). Indeed, sequential bilateral TKA present several benefits, as one single anesthesia, surgical episode, hospitalization, and rehabilitation. The purpose of our study was to evaluate peri-operative outcomes and compare the complication rates, clinical outcomes, and implant positioning of sequential bilateral TKA performed with a robotic-assisted system versus a conventional technique.

MATERIALS AND METHODS

All patients who underwent a sequential bilateral robotic-assisted primary TKA (raTKA) in our institution between November 2019 and February 2021 were included. Twenty patients met the inclusion criteria and were matched with 20 sequential bilateral TKA performed with a conventional technique. The two groups were comparable for the demographic data and the preoperative parameters, including preoperative anticoagulation and ASA score. The minimum follow-up was 6 months.

RESULTS

The operative time was significantly longer in the robotic group (< 0.0001), with a mean additional time of 29 min. There was no significant difference between both groups for postoperative blood loss, rate of blood transfusion, or postoperative pain. The average length of stay was 5 days. There was one early complication in the robotic group due to the tibial trackers. The functional outcomes were similar between both groups, except for the functional KSS score, which was better at 6 months in the robotic group (p < 0.0001). The restoration of the knee alignment and the distal femoral anatomy were significantly better in the robotic group than in the conventional group.

CONCLUSIONS

Despite a longer operative time, the peri-operative parameters of sequential bilateral TKA were similar between robotic and conventional techniques. Further, sequential bilateral raTKA was at least as safe as a conventional technique, without additional risk of medical complications.

Safe and reliable clinical outcomes at 2 years of a fixed-bearing partial knee arthroplasty with a morphometric tibial tray in a large worldwide population

PURPOSE

The purpose of this study was to evaluate: (1) improvement of functional and quality of life scores, (2) adverse events, (3) short-term implants survivorship of a newly designed fixed-bearing partial knee replacement (PKR) with a morphometric tibial tray in a large and multicentric population at a minimum follow-up of 2 years.

METHODS

From 2017 to 2019, 479 medial PKR were implanted by 16 non-developing surgeons from United States, Europe, and Japan. Eight patients were lost to follow-up (1.8%). Standardized follow-up procedures included patient-reported outcomes (Oxford Knee Society score, Forgotten Joint Score, EQ VAS, EQ 5D), patient satisfaction, radiographic assessments, adverse event at 2 years. Comparisons between the preoperative and postoperative values were performed using Student t test. Kaplan-Meier survivorship analysis was performed with knee revision as the endpoint.

RESULTS

The mean age was 65.6 ± 9.6 years. Mean body mass index was 29.5 ± 5.1 kg/m². Oxford Knee Society score and Forgotten Joint Score, respectively, improved from 23.7 ± 8 and 16 ± 15.8 preoperatively to 42.4 ± 6.5 and 74 ± 24.9 at 2 years (p < 0.0001). Satisfaction Score was 92.3 ± 13.4 at 2 years. Ten re-operations (2.1%) were reported including seven implant removals (1.5%). No other adverse event was reported. The causes of conversion to total knee arthroplasty were: nickel allergy (n = 2), patellofemoral osteoarthritis (n = 1), pain (n = 1), deep infection (n = 3). Two re-operations were performed due to infection, and one for internal fixation for a tibial plateau fracture. The 2-year Kaplan-Meier survival estimate was 98.4%, with implant removals as the endpoint.

CONCLUSION

This prospective multicentric study reported safe and reliable clinical outcomes of a morphometric PKR, which optimized tibial coverage and femoral fit, in a large population of patients worldwide at 2 years.

LEVEL OF EVIDENCE

Prospective cohort study-therapeutic study, Level II.

Early outcomes using a 'kinematic retaining' total knee replacement - A multicentre prospective study at two years follow-up

BACKGROUND

Although predictable implant longevity in total knee replacement (TKR) is now established, work continues to satisfy the demands of patients who seek full restoration of the painless function of the native knee following TKR. This prospective study examines the early clinical outcomes of 156 patients implanted with a novel 'kinematic-retaining' (KR) implant.

METHODS

156 Physica KR TKRs were implanted for primary osteoarthritis at three European centres. Patients were reviewed up to two years using radiographic, clinical and functional evaluations.

RESULTS

Of the 137 patients retained at two years' follow up, none had been revised. Within 6 post-operative months, 51.7% and 79.9% had excellent clinical and functional KSS values respectively, increasing to 81.8% and 88.3% beyond two years. Mean KSS improvement was 34.8 (from 48.6 to 83.4). All KOOS sub-scores improved significantly with total KOOS improving from a mean of 35.5 (SD ±13.0) to 86.5 (±13.7) at two years post-operatively. Pain and sports KOOS sub-scores improved rapidly during the early post-operative periods, with sustained improvements beyond this. Mean OKS improved by 44.1 (±5.1) at two years. VAS satisfaction scores improved significantly at all time points beyond six weeks. Mean FJS-12 was 75.7 at two years, with no significant effects of age or gender. No progressive adverse radiographic features were noted.

CONCLUSIONS

Early clinical and radiographic outcomes of this kinematic-retaining knee prosthesis are promising, with improvements in clinical parameters similar to, or exceeding those published in other contemporary TKR designs.

LEVEL OF EVIDENCE

II, Multicentre Prospective cohort study.

Safety and Efficacy of Single Condylar Knee Prosthesis When Treating Knee Single Compartment Osteoarthritis: A Prospective, Case-Randomized Controlled Study

Objective. The aim of this study is to explore the safety and efficacy of single condylar knee prosthesis when treating knee single compartment osteoarthritis by measuring the decrease of hemoglobin, total postoperative blood loss, maximum reduction of HCT, and knee joint activity. Methods. A total of 80 patients with knee joint single compartment osteoarthritis treated in our hospital from January 2020 to December 2021 were studied. They were randomly assigned to a study group (n = 40) and a control group (n = 40). The study group was treated with total knee prosthesis, while the control group was treated with simple knee prosthesis. The decrease rate of hemoglobin, the amount of bleeding, and the maximum decrease of hematocrit were compared after treatment. The range of motion of knee joint was evaluated by the Fugl-Meyer motor function scale (FM-B) and Berg balance scale (BBS). Results. The decrease of hemoglobin in the study group at 24 hours, 36 hours, and 48 hours after treatment was remarkably lower ( $P$  < 0.05). The total blood loss and the maximum reduction of hematocrit(HCT) in the study group were lower ( $P$  < 0.05). The range of motion (ROM) of the knee joint in the study group at 6 and 12 months after treatment was remarkably higher than that before treatment and remarkably higher compared to the control group ( $P$  < 0.05). The FM-B scale and BBS scale of the studied cohort at 6 and 12 months after treatment were remarkably higher than those before treatment and were remarkably higher compared to the control’s ( $P$  < 0.05). Conclusion. The unicondylar knee prosthesis is safer and more effective in the treatment of noncompartmental osteoarthritis of the knee, facilitating less trauma and perioperative blood loss and enhancing the patient’s motion and balance.