Total Knee Arthroplasty After Failed Unicompartmental Knee Arthroplasty. Clinical Results, Radiologic Findings, and Technical Tips

Unicompartmental knee arthroplasties: does the type of tibial component selected influence implant survival?

INTRODUCTION

Few information has been published on the survival of unicompartmental knee arthroplasty (UKA) and fixed-bearing tibial components. The aim of this study is to analyze if UKA survival varies according to UKA model used and to analyze the possible risk factors for UKA revision.

MATERIALS AND METHODS

A retrospective study analyzing 301 UKAs (ACCURIS, all-polyethylene tibial component, 152; Triathlon PKR, metal-backed tibial component, 149) was performed. Demographic parameters as well as implant survival and cause of prosthetic revision were analyzed. The Kaplan-Meier survival analysis, the log-rank test and the Cox multiple regression were used for the analysis.

RESULTS

Average follow-up was 8.1 ± 3.08-years. Average age was 68.1 ± 8.6-years; 70.4% of subjects were women. The ACCURIS UKA group had a UKA revision rate higher compared to the Triathlon PKR group (16/152, 10.6% vs 5/149, 3.4%, respectively; p < 0.001). The main cause of prosthetic revision was aseptic loosening (5/21, 23.8%). All aseptic loosening cases and tibial component collapse were reported with the ACCURIS UKA group. Overall UKA survival was 98.01% (95% CI 95.62-99.1) at 1-year, 94.27% (95% CI 90.95-96.4) at 5-years and 92.38% (95% CI 88.48-94.99) at 10-years' follow-up. There were no differences in the Kaplan-Meier survival curves regarding operated side or affected tibiofemoral compartment (log-rank test = 0.614 and 0.763, respectively). However, Kaplan-Meier survival curve according to UKA model used was different (log-rank test = 0.033). The metal-backed component appeared to be a protector factor for UKA revision when adjusted for age, sex, operated side, and affected tibiofemoral compartment (Hazard Ratio 0.32, p = 0.031).

CONCLUSION

Fixed-bearing UKAs showed excellent mid- and long-term survival rates. Aseptic loosening is the main cause of implant failure. PKR group (metal-backed component) seem to be a protector factor to UKA revision when it was compared with ACCURIS UKA group (all-polyethylene tibial component).

Clinical outcomes of various types of revision surgeries after unicompartmental knee arthroplasty failure

PURPOSE

The advantages of unicompartmental knee arthroplasty (UKA) have led to the procedure being increasingly performed worldwide. However, revision surgery is required after UKA failure. According to the literature review, the choice of implant in revision surgery remains a debatable concern. This study analyzed the clinical results of different types of prostheses used in treating failed UKA.

MATERIALS AND METHODS

This is a retrospective review of 33 failed medial UKAs between 2006 and 2017. Demographic data, failure reason, types of revision prostheses, and the severity of bone defects were analyzed. The patients were classified into three groups: primary prosthesis, primary prosthesis with a tibial stem, and revision prosthesis. The implant survival rate and medical cost of the procedures were compared.

RESULTS

A total of 17 primary prostheses, 7 primary prostheses with tibial stems, and 9 revision prostheses were used. After a mean follow-up of 30.8 months, the survival outcomes of the three groups were 88.2%, 100%, and 88.9%, respectively (P = 0.640). The common bone defect in tibia site is Anderson Orthopedic Research Institute [AORI] grade 1 and 2a (16 versus 17). In patients with tibial bone defects AORI grade 2a, the failure rates of primary prostheses and primary prostheses with tibial stems were 25% and 0%, respectively.

CONCLUSIONS

The most common cause for UKA failure was aseptic loosening. The adoption of a standardized surgical technique makes it easier to perform revision surgeries. Primary prostheses with tibial stems provided higher stability, leading to a lower failure rate due to less risk of aseptic loosening in patients with tibial AORI grade 2a. In our experience, we advise surgeons may try using primary prostheses in patients with tibial AORI grade 1 and primary prostheses with tibial stems in patients with tibial AORI grade 2a.

Higher survival rate in total knee arthroplasty after high tibial osteotomy than that after unicompartmental knee arthroplasty

PURPOSE

The objective of this study was to evaluate the survival rates and complications in TKA after UKA and HTO as compared with primary TKA using national health data. It was hypothesized that survival and complication rates would be worse in patients with a history of UKA or HTO compared to primary TKA.

METHODS

Based on a list of patients who underwent TKA from Korean National Health Insurance database, 315,071 underwent primary TKA (group A); 2177 TKA after HTO (group B); and 1284 TKA after UKA (group C). Revision rates were compared between the groups using log-rank tests and adjusted hazard ratios (HR) of groups B and C were compared with those of the reference group (group A). A total of 1000 TKA matched patients were assigned to groups B and C according to propensity score for comparing revision rates after TKA and perioperative complication rates between TKA after HTO and UKA.

RESULTS

The overall revision rate was 2.1% in group A, 2.0% in group B, and 4.2% in group C. The revision rate until 10 years after TKA was significantly higher in group B (p = 0.03) or C (p < 0.0001) than in group A. The hazard ratios for revision was significantly higher in group A than in groups B and C at 10 years after index TKA (1.4 in group B and 3.7 in group C). The result of the comparison using PSM between TKA after HTO and UKA showed that TKA after HTO had lower risk of revision than TKA after UKA (HR: 0.41 at 10 years). However, no statistically significant differences in the perioperative complication rate between the two groups were found. (NS, not significant) CONCLUSIONS: TKA after UKA or HTO showed a significantly higher risk of revision than primary TKA. While TKA after HTO showed lower risk of revision than TKA after UKA, no significant differences in complications between TKA after UKA and HTO were found. Thus, surgeons must be aware of the low survival rate in TKA after UKA or HTO, especially in TKA after UKA.

LEVEL OF EVIDENCE

III (Retrospective cohort study).

Analysis of the following Related Surgeries of Unicompartmental Knee Arthroplasty and Total Knee Arthroplasty: A Taiwanese National Health Insurance Research Database Population-Based Study

Background

Current treatment options for both unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) are still controversial with no consistent results in which one is superior to others. This is the first study to examine and analyze the following related data available in patients receiving either UKA or TKA from the National Health Research Database (NHIRD) in Taiwan.

Methods

The database was searched from NHIRD, pooling one million random patients. Patients' age, gender, and comorbidities were analyzed in either UKA or TKA between January 2005 and December 2013, or up until death. For the patients that had received bilateral surgeries, further subgrouping was divided into TKA to TKA, UKA to UKA, TKA to UKA, and UKA to TKA to analyze the completion rate curve. Additional analysis of the order codes 64202B, 64053B, and 64198B was defined as failures, and the related failure rate curves were analyzed separately within ten years. Finally, infection-related codes were analyzed.

Results

6,179 patients (n = 276 UKA; n = 5903 TKA) were selected. Age (p < 0.0001) and gender (p = 0.037) had significant differences, with more young population and males having UKA than TKA. Most comorbidities had no significant difference. For the bilateral surgery analysis, the UKA to UKA group had the fastest completion rate (p < 0.001) and UKA to TKA was the slowest. There were no significant differences in the failure rates of 64202B, 64053B, and 64198B.

Conclusion

Most UKA and TKA are appropriate solutions to treat patients with osteoarthritis or osteonecrosis. UKA to UKA is the quickest bilateral completion surgery, and UKA has a higher chance of undergoing revision surgery than TKA.

Revision of Unicompartmental to Total Knee Arthroplasty: Does the Unicompartmental Implant (Metal-Backed vs All-Polyethylene) Impact the Total Knee Arthroplasty?

BACKGROUND

The aim of this study is to investigate differences in implant requirement, outcomes, and re-revision when total knee arthroplasty (TKA) was performed following unicompartmental knee arthroplasties (UKAs) with metal-backed (MB) compared to all-polyethylene (AP) tibial components.

METHODS

Retrospective study of 60 UKAs converted to 60 TKAs at mean 7.3 years (0.1 to 17) after implantation in 55 patients (mean age, 64 [49-83]; 44% male): 44 MB and 16 AP. TKA implant requirement was investigated in addition to mode of failure, Oxford Knee Score, and TKA survival at mean 5.4 years (0.5 to 17).

RESULTS

Progression of osteoarthritis was the commonest mode of failure in MB UKAs (P = .03) and unexplained pain in AP (P = .011) where revisions were performed earlier (4.8 ± 3.2 vs 8.2 ± 4.5, P = .012). In 56 of 60 (93%) cases, unconstrained TKA implants were used. The use of standard cruciate-retaining TKAs without augments or stems was less likely following MB UKA compared to AP (12 of 38 [32%] vs 10/14 [71%], P = .013). Specifically MB UKA implants were associated with more tibial stem use (P = .04) and more use of cruciate-substituting polyethylene (P = .05). There was no difference in the use of constrained implants. Multivariate analysis showed tibial resection depth to predict stem requirement. Seven were re-revised giving 7-year TKA survival: from MB UKA 70.3 (95% CI, 47.0 to 93.6) and from AP UKA 87.5 (95% CI, 64.6 to 100; P = .191).

CONCLUSION

MB UKA implants increase the chances of a complex revision requiring tibial stems and cruciate substitution but reduce the chances of early revision compared to AP UKA which often fail early with pain.

Effects of Lower Limb Alignment and Tibial Component Inclination on the Biomechanics of Lateral Compartment in Unicompartmental Knee Arthroplasty

Background:

Lateral compartmental osteoarthritis (LCOA), a major complication after medial mobile-bearing unicompartmental knee arthroplasty (UKA), is highly associated with the increased stress of the lateral compartment. This study aimed to analyze the effects on the stress and load distribution of the lateral compartment induced by lower limb alignment and coronal inclination of the tibial component in UKA through a finite element analysis.

Methods:

Eight three-dimensional models were constructed based on a validated model for analyzing the biomechanical effects of implantation parameters on the lateral compartment after medial Oxford UKA: postoperative lower limb alignment of 3° valgus, neutral and 3° varus, and the inclination of tibial components placed in 4°, 2° valgus, square, and 2° and 4° varus. The contact stress of femoral and tibial cartilage and load distribution were calculated for all models.

Results:

In the 3° valgus lower limb alignment model, the contact stress of femoral (3.38 MPa) and tibial (3.50 MPa) cartilage as well as load percentage (45.78%) was highest compared to any other model, and was increased by 36.75%, 47.70%, and 27.63%, respectively when compared to 3° varus. In the condition of a neutral position, the outcome was comparable for the different tibial tray inclination models. The inclination did not greatly affect the lateral compartmental stress and load distribution.

Conclusions:

This study suggested that slightly varus (undercorrection) lower limb alignment might be a way to prevent LCOA in medial mobile-bearing UKA. However, the inclination (4° varus to 4° valgus) of the tibial component in the coronal plane would not be a risk factor for LCOA in neutral position.

Revision of partial knee to total knee arthroplasty with use of patient-specific instruments results in acceptable femoral rotation

PURPOSE

Patient-specific instruments (PSI) were initially developed for the alignment of both total knee- (TKA) and partial knee arthroplasty (PKA). We hypothesize that CT-based PSI for PKA-to-TKA revision surgery can restore biomechanical limb alignment and prosthetic component positioning in vivo as calculated pre-operatively, resulting in a limited percentages of outliers.

METHODS

An imaging analysis was performed using CT-based 3D measurement methods based on a pre- and post-revision CT scan. Imaging data were gathered on 10 patients who were operated for PKA-to-TKA revision with the use of PSI based on CT imaging. The planned femur and tibia component position in vivo were compared with the pre-revision planned component position. Outliers were defined as deviations >3.0° from pre-revision planned position for the individual implant components. Adjustments (e.g. resection level and implant size) during surgery were recorded.

RESULTS

The HKA axis was restored accurately in all patients with a mean post-operative HKA axis of 178.1° (1.4°). Five femoral (2 varus, 2 internal rotation and 1 extension) and 14 tibial guides (2 varus, 6 anterior slope, 3 internal rotation and 3 external rotation) on a total of 60 outcome measures were identified as outliers. During surgery, an intraoperative tibial resection of 2 mm extra was performed in three patients. In 80 and 70% for, respectively, the femur and tibia, the surgeon-planned size was implanted during surgery. All patient-specific guides fitted well in all patients. No intraoperative or post-operative complications related to surgery were registered.

CONCLUSIONS

This study introduced a unique new concept regarding PSI, PKA-to-TKA revision surgery. Based on the results, we were unable to fully confirm our hypothesis. PSI as a "new" tool for PKA-to-TKA revision surgery appears to be an accurate tool for the alignment of the TKA femur component. The tibial guide seems more susceptible to errors, resulting in a substantial percentage of outliers.

LEVEL OF EVIDENCE

Prospective cohort study, Level II.

Elastomeric Lumbar Total Disc Replacement: Clinical and Radiological Results With Minimum 84 Months Follow-Up

BACKGROUND

Total lumbar disc replacement (TDR) devices have been designed to maintain motion, but both biomechanical and clinical data have indicated that a more controlled motion and additional load absorption in TDR would be beneficial. This work analyzed long-term results of an elastomeric disc (Physio-L) for degenerative lumbar conditions.

MATERIAL AND METHODS

This was a prospective, noncomparative, single-center clinical and radiological study. A total of 15 patients with predominant low back pain due degenerative disc disease received anterior total disc replacement with a Physio-L disc. Clinical outcomes were assessed both with a visual analog scale for pain and Oswestry Disability Index questionnaires. Radiological outcomes included implant failure, range of motion (ROM), facet degeneration, and adjacent level disease. Complication and reoperation rates were also recorded. The cases were assessed with a minimum follow-up of 84 months.

RESULTS

A total of 15 patients were enrolled (20 TDRs)-10 single-level cases (L5S1) and 5 two-level cases (L4L5/L5S1). After 84 months, clinical outcomes scores still demonstrated significant improvement compared with baseline (P < .001). Mean visual analog scale scores dropped from 7.1 to 2.9, and the Oswestry Disability Index improved from 50 to 16. No disc has experienced migration or breakage. The average range of motion value went from a baseline of 12.0° to 13.3° at 12 months, and at the final follow-up it decreased to 9.9°. Regarding the double-level cases, 3 of 5 (60%) had adverse events; just 1 single-level (10%) had adverse events. At final follow-up, radiological signs of facet degeneration were present in 7 of 15 patients (47%) but with only 1 of 15 (6.7%) symptomatic. Two patients (13%) required surgery at the adjacent level. At the 84-month follow-up, 16 of 18 prostheses (89%) were still active (2 revised to fusion and 2 were lost to follow-up).

CONCLUSION

The long-term follow-up data shows satisfactory clinical results for the use of Physio-L elastomeric TDR in the treatment of degenerative disc disease. Studies with bigger cohorts are needed to replicate results and add new information regarding other details.

Good results with minimally invasive unicompartmental knee resurfacing after 10-year follow-up

The current study was designed to determine (1) 10-year implant survival and (2) patient's self-reported functional outcome in a single surgeon's consecutive cohort of patients who had undergone minimally invasive unicondylar resurfacing with a modified cementation technique utilizing a cobalt-chromium femur/inlaid all-PE tibia, fixed-bearing unicompartmental prosthesis. We included 344 consecutive patients (361 knees) who had received the study device between January 2002 and December 2005 in this retrospective study. After 10 years, 78 patients (78 knees) had died, 59 (59 knees) were lost to follow-up and four (four knees) did not participate. Thirteen knees (11 patients) were revised after a mean of 5.8 ± 1.9 years. Hence, the study population at follow-up comprised 192 patients (207 knees). Ten-year implant survival was 94.6% (95% confidence interval, 90.9-96.8%). The Forgotten Joint Score and Oxford Knee Score were 68.9 ± 28.9 and 39 ± 9.1, respectively. Excellent survivorship and clinical outcomes were obtained with UKA with an inlaid all-PE tibia with a modified cementation technique.

Revision total knee arthroplasty for failed high tibial osteotomy and unicompartmental knee arthroplasty have similar patient-reported outcome measures in a two-year follow-up study

Aims

Little is known about the relative outcomes of revision of unicompartmental knee arthroplasty (UKA) and high tibial osteotomy (HTO) to total knee arthroplasty (TKA). The aim of this study is to compare the outcomes of revision surgery for the two procedures in terms of complications, re-revision and patient-reported outcome measures (PROMs) at a minimum of two years follow-up.

Patients and Methods

This study was a retrospective review of data from an institutional arthroplasty registry for cases performed between 2001 and 2014. A total of 292 patients were identified, of which 217 had a revision of HTO to TKA, and 75 had revision of UKA to TKA. While mean follow-up was longer for the HTO group compared with the UKA group, patient demographics (age, body mass index and Charlson co-morbidity index) and PROMs (Short Form-36, Oxford Knee Score, Knee Society Score, both objective and functional) were similar in the two groups prior to revision surgery. Outcomes included the rate of complications and re-operation, PROMS and patient-reported satisfaction at six months and two years post-operatively. We also compared the duration of surgery and the need for revision implants in the two groups.

Results

At two-year follow-up, both groups of patients had made significant improvement in terms of PROMs compared with pre-operative scores. PROMs and satisfaction rates were similar in the two groups. Complications requiring re-operation were significantly more frequent in the HTO group whilst more revision implants were used in the UKA group, resulting in a longer operative duration.

Conclusion

Revision of HTO and UKA achieve similar post-operative PROMs and satisfaction. Revision of UKA more frequently requires revision components with increased operation duration but fewer complications requiring re-operation compared with revision of HTO. Cite this article: Bone Joint J 2017;99-B:1329–34.