Clinical outcomes after high-flex versus conventional total knee arthroplasty

Long-Term Assessment of Highly Cross-Linked and Compression-Molded Polyethylene Inserts for Posterior Cruciate-Substituting TKA in Young Patients: A Concise Follow-up of a Previous Report

The purpose of the present study was to determine the long-term clinical and radiographic results, survival rate, prevalence of osteolysis, and prevalence of fracture of the tibial polyethylene insert following total knee arthroplasty (TKA). Three hundred patients (600 knees) were included in this follow-up study. The mean age of the patients (and standard deviation) was 60.3 ± 4.3 years, and the mean duration of follow-up was 13.2 years (range, 12 to 14 years). Revision of the TKA prosthesis was performed in 7 knees (2.3%) with a compression-molded polyethylene (CPE) tibial insert and 6 knees (2%) with a highly cross-linked polyethylene (HXLPE) tibial insert. The rate of survival at 14 years was 97.7% (95% confidence interval [CI], 94%-100%) in the CPE group and 98% (95% CI, 94%-100%) in the HXLPE group with reoperation for any reason as the end point. The rate of survival at 14 years was 98% (95% CI, 94%-100%) in both groups with reoperation for mechanical failure as the end point. No knee had osteolysis or fracture of the tibial polyethylene insert. There were no between-group differences. LEVEL OF EVIDENCE:: Therapeutic Level I. See Instruction for Authors for a complete description of levels of evidence.

Comparison of Revision Rates Due to Aseptic Loosening between High-Flex and Conventional Knee Prostheses

Purpose

The purpose was to evaluate and compare the revision rate due to aseptic loosening between a high-flex prosthesis and a conventional prosthesis.

Materials and Methods

Two thousand seventy-eight knees (1,377 patients) with at least 2 years of follow-up after total knee arthroplasty were reviewed. Two types of implants were selected (LPS-Flex and LPS, Zimmer) to compare revision and survival rates and sites of loosened prosthesis component.

Results

The revision rate of the LPS-Flex (4.9%) was significantly higher than that of the conventional prosthesis (0.6%) (p<0.001). The 5-, 10-, and 15-year survival rates were 98.9%, 96.2% and 92.0%, respectively, for the LPS-Flex and 99.8%, 98.5% and 93.5%, respectively, for the LPS. The survival rate of the high-flex prosthesis was significantly lower than that of the conventional prosthesis, especially in the mid-term period (range, 5 to 10 years; p=0.002). The loosening rate of the femoral component was significantly higher in the LPS-Flex prosthesis (p=0.001).

Conclusions

The LPS-Flex had a higher revision rate due to aseptic loosening than the LPS prosthesis in the large population series with a long follow-up. The LPS-Flex should be used carefully considering the risk of femoral component aseptic loosening in the mid-term (range, 5 to 10 years) follow-up period after initial operation.

Antibiotic Prophylaxis and DAIR Treatment in Primary Total Hip and Knee Arthroplasty, A National Survey in The Netherlands

BACKGROUND

To prevent postoperative infection the use of systemic antibiotic prophylaxis is common ground. Type of antibiotic used and duration of prophylaxis are subject to debate. In case of suspected early periprosthetic infection a debridement, antibiotics and implant retention (DAIR) procedure is treatment of first choice. This study evaluated the antibiotic prophylaxis and DAIR treatment protocols nationwide as well as reporting of these DAIR procedures to the national joint registry.

METHODS

All institutions that performed total hip or knee arthroplasty were contacted to complete a 16-question online survey. Questions included availability of a protocol, type and duration of antibiotic prophylaxis used and tendency to register infectious complications in the Dutch Arthroplasty Register.

RESULTS

All ninety-nine consulted institutions responded to this survey. All but one institutions have a standardized hospital based protocol for antibiotic prophylaxis in primary total hip or knee arthroplasty. Cefazolin was antibiotic prophylaxis of choice in ninety-four institutions for both primary hip and knee arthroplasty. In ten institutions one preoperative gift of antibiotic prophylaxis was administered. A protocol describing treatment when suspecting early periprosthetic joint infection was present in seventy-one institutions. When performing a DAIR procedure modular parts were exchanged in seventy institutions in case of a hip prosthesis and in eighty-one institutions in case of a knee prosthesis. Sixty-three institutions register DAIR procedures in the Dutch Arthroplasty Register.

INTERPRETATION

In contradiction to the results of a recent study in Great Britain, we have found only little variety in availability of protocols and in the type of antibiotic used as prophylaxis in primary total hip and knee arthroplasty in The Netherlands. Not every institution has a protocol for treatment in suspicion of early infection. Although mobile parts are exchanged in the majority of cases, there appears to be an underreporting of DAIR procedures in the Dutch Arthroplasty Register.

Single-stage total knee arthroplasty and osteotomy as treatment of secondary osteoarthritis with severe coronal deviation of joint surface due to extra-articular deformity

PURPOSE

Severe extra-articular deformities can be treated with single-stage total knee replacement (TKA) and osteotomy. Aim of this study was to examine the patient-reported outcome measures (PROMs) and the complications after single-stage TKA and osteotomy. We hypothesized patients achieve good outcome after single-stage TKA and osteotomy, which is comparable to outcome after primary TKA without deformity.

METHODS

Twenty-one patients with severe extra-articular deformity who underwent single-stage TKA and deformity-correcting osteotomy were reviewed and invited to fill in PROMs including the Oxford Knee Score, the Short Form-12, a Visual Analogue Scale for pain, and questions about satisfaction and quality of life.

RESULTS

The mean follow-up period was 64 months. Ten patients were treated with TKA and supracondylar femoral osteotomy. Although PROMs showed good results (mean quality of life score was 85 out of 100), two patients had a revision of the osteotomy due to non-union. Eleven patients were treated with TKA and high tibial osteotomy. Patients were satisfied with the results (mean quality of life score was 81 out of 100). Two patients developed infection requiring debridement, resulting in one arthrodesis and one gastrocnemius transfer for wound closure.

CONCLUSION

In general, patients were satisfied with the postoperative result. Outcome was comparable to patients after primary TKA in the literature. However, serious complications need to be taken into account.

LEVEL OF EVIDENCE

III.

Clinical outcome of increased flexion gap after total knee arthroplasty. Can controlled gap imbalance improve knee flexion?

PURPOSE

Increased range of motion (ROM) while maintaining joint stability is the goal of modern total knee arthroplasty (TKA). A biomechanical study has shown that small increases in flexion gap result in decreased tibiofemoral force beyond 90° flexion. The purpose of this paper was to investigate clinical implications of controlled increased flexion gap.

METHODS

Four hundred and four TKAs were allocated into one of two groups and analysed retrospectively. In the first group (n = 352), flexion gap exceeded extension gap by 2.5 mm, while in the second group (n = 52) flexion gap was equal to the extension gap. The procedures were performed from 2008 to 2012. The patients were reviewed 12 months postoperatively. Objective clinical results were assessed for ROM, mediolateral and sagittal stability. Patient-reported outcome measures were the WOMAC score and the Forgotten Joint Score (FJS-12).

RESULTS

After categorizing postoperative flexion into three groups (poor < 90°, satisfactory 91°-119°, good ≥ 120°) significantly more patients in group 1 achieved satisfactory or good ROM (p = 0.006). Group 1 also showed a significantly higher mean FJS-12 (group 1: 73, group 2: 61, p = 0.02). The mean WOMAC score was 11 in the first and 14 in the second group (n.s.). Increase in flexion gap did not influence knee stability.

CONCLUSIONS

The clinical relevance of this study is that a controlled flexion gap increase of 2.5 mm may have a positive effect on postoperative flexion and patient satisfaction after TKA. Neither knee stability in the coronal and sagittal planes nor complications were influenced by a controlled increase in flexion gap.

LEVEL OF EVIDENCE

III.

A Comparison of 5 Models of Total Knee Arthroplasty in Young Patients

BACKGROUND

Several different total knee implants were introduced in an attempt to potentially improve outcomes of total knee arthroplasty in young patients. The object of this study was to compare the clinical outcomes of 5 models of total knee implants.

METHODS

We compared 172 patients who received posterior substituting knee implants with an average 13.2-year follow-up, 182 patients who received high-flex knees with an average 11.8-year follow-up, 190 patients who received mobile-bearing knees with an average 13.9-year follow-up, 170 patients who received gender-specific knees with an average 10.8-year follow-up, and 192 patients who received oxidized zirconium knees with an average 13.5-year follow-up. There were 186 men and 720 women (mean age, 53.3 years; range, 40-60). The mean follow-up was 12.6 years.

RESULTS

We found similar postoperative Knee Society knee and function scores (P = .693 and P = .698, respectively), postoperative Western Ontario MacMaster Universities Osteoarthritis Index score (P = .523), University of California, Los Angeles activity score (P = .651) and range of knee motion (P = .417), radiographic results (P > .05), revision rates (P = .241), and survivorship (P = .981) of the implants.

CONCLUSIONS

Range of knee motion, prevalence of polyethylene wear, osteolysis, revision rates, and survivorship of 5 models of total knee arthroplasties were similar. We believe that good designs with a good quality of polyethylene and defined surgical techniques provided good clinical and radiographic outcomes of these 5 models of total knee arthroplasties at this length of follow-up.