Minimal incision surgery as a risk factor for early failure of total knee arthroplasty

Journey-Deuce bicompartmental knee arthroplasty with the addition of computer navigation achieves good clinical outcomes and implant survival at 10 years

PURPOSE

To report 10-year outcomes and survivorship in patients undergoing bicompartmental knee arthroplasty (BCKA) using the Journey-Deuce prosthesis in a consecutive prospective case series.

METHODS

Between November 2006 and November 2009, 41 patients with a mean age of 69.6 years (range 51-86) underwent 51 bicompartmental knee arthroplasties with the Journey-Deuce knee prosthesis. All patients presented with symptomatic medial and patellofemoral compartment osteoarthritis, with intact cruciate ligaments and a preserved lateral compartment on plain radiographs and Magnetic Resonance Imaging. Clinical assessment was undertaken pre-surgery and at 1, 2, 5 and 10 years post-surgery using the Oxford Knee Score (OKS), EuroQol Group 5-Dimension self-reported questionnaire (EQ-5D) and maximal active range of motion (ROM).

RESULTS

30 patients (37 knees) were followed-up at a mean time of 11.4 years (SD 1.1; range 10.5-14.0). Eight patients (ten knees) were deceased and three could not be contacted at final review. No major component revision was performed. Pre-operative OKS 25.4 (SD 5.2; range 15-40), knee flexion 116.4° (SD 10.3°; range 100°-140°) and EQ-5D 70.5 (SD 19.9; range 25-95). 10-year OKS 43.5 (SD 4.1; range 32-48), knee flexion 127.3° (SD 11.1°; range 105°-144°) and EQ-5D 77.4 (SD 9.3; range 60-100). The OKS (p < 0.0001), EQ-5D (p = 0.024) and active knee flexion ROM (p < 0.0001) all significantly improved from pre-surgery to 1-year post-surgery, with no further significant changes in these scores between any post-operative time period up until 10 years. 32% (7/22) of tibial and 45% (10/22) of femoral components showed progressive radiolucencies between 2 and 5-year and 10-year follow-up.

CONCLUSIONS

This is the largest cohort of patients having undergone BCKA (with the Journey-Deuce prosthesis) with longest follow-up described in the literature. At 10 years, patients presented with significantly improved clinical outcomes, comparable to other surgical arthroplasty options. No major component revision was performed. Progressive radiolucencies were noted in 32% of tibial and 45% of femoral components without corresponding clinical signs of loosening.

LEVEL OF EVIDENCE

Level III.

Outcomes of total knee replacement with the use of a NexGen MIS Tibial Component (Mini-keel) : a systematic review

NexGen MIS Tibial Component (Mini-keel) is a tibial component specially developed for minimally invasive surgery in total knee replacement (TKR), and the size limitations of its design and the modular system could affect tibial fixation strength, however, this has not been precisely evaluated thus far. This study aimed to systematically review the literature describing the outcome following TKR with the use of a Mini-keel. Electronic searches of databases were undertaken in July 2019 by two experienced orthopaedic surgeons according to the PRISMA guidelines for literature describing the outcomes of TKR with the use of a Mini-keel. Quality of studies was assessed using the Joanna Briggs Institute Critical Appraisal Checklist. The initial search found a total of 623 studies from all the databases. Seven studies met all the inclusion criteria and were eligible for critical appraisal and quality assessment. In total, 2,198 cases were included in the systematic review. Thirty-five revision cases due to aseptic loosening were found from the systematic review. Two studies were negative about using a Mini-keel and three studies were positive about it, while the other two studies did not judge the quality of a Mini-keel. There have been conflicting conclusions among studies for the use of a Mini-keel. There remains a paucity of prospective cohort studies between TKRs with the use of a Mini-keel and those with the use of a conventional implant, which makes it difficult to determine the usefulness and reliability of this implant.

Comparative Efficacy of the Different Surgical Approaches in Total Knee Arthroplasty: A Systematic-Review and Network Meta-Analysis

BACKGROUND

Several surgical approaches including midvastus, subvastus, mini-parapatellar, quadriceps-sparring (QS) and parapatellar are currently used to perform total knee arthroplasty (TKA). Since none of published study exhibited a simultaneous comparison of all of them, a network meta-analysis has been conducted to compare the most widely used knee surgical approaches regarding the improvement of functional outcomes and the range of motion (ROM).

METHODS

Randomised controlled trials (RCTs) comparing TKA approaches were searched in electronic databases, major orthopedics journals, and oral communications, ClinicalTrials.gov and WHO International Clinical Trials Registry Platform until May 1st, 2020. Two reviewers independently selected trials and extracted data. The primary outcomes were functional scores at 6 months post-surgeryevaluated by KSS and WOMAC, and the ROM.

RESULTS

Sixty RCTs involving 5042 patients with 5107 TKA were included. No significant differences between different approaches were found for the KSS assessment or the WOMAC at 6 months. The mean of ROM at 6 months post-surgery were higher in the subvastus group than in all the others surgical approaches. The difference of ROM with subvastus approach was 7.3° (95% CI -14.1 to -0.1) with the midvastus approach, 11.1° (95% CI -18.7 to -2.8) with mini-parapatellar, 8.9° (95% CI -14.2 to -3.1) with standard parapatellar, and 9.2° (95% CI -16.1 to -1.8) with QS.

CONCLUSION

No differences were found in functional outcomes over short or medium terms but subvastus seemed to increase the ROM at 6 months post-surgery. Until or unless future studies can demonstrate a long-term benefit, based on these results all studied surgical approaches to perform a TKA are equal.

LEVEL OF EVIDENCE

Network meta-analysis. Level 1.

Analysis of learning curve of minimally invasive total knee arthroplasty: A single surgeon's experience with 4017 cases over a 9-year period

BACKGROUND

To evaluate a single surgeon's experience with minimally invasive total knee arthroplasty (MIS-TKA) and report the 9-year learning curve and trends in clinical outcomes based on assessment of surgical skills, radiographic alignments, and patient's function scores.

METHODS

This retrospective study included a total of 4107 knees from 3403 patients undergoing bilateral or unilateral MIS-TKA between March 2004 and February 2013. MIS-TKA was performed through a modified mini-midvastus approach. Postsurgical care regime was standardized for all patients. Data of consecutive 3-month intervals were collected and compared for changes of trends in outcomes over time, including tourniquet time, intraoperative complications, radiographic alignment, the Knee Society Score (KSS), and functional scores.

RESULTS

Significant increase in the number of cases undergoing MIS-TKA per 3-month interval over the study period was observed. As surgeon's experience increased over time, tourniquet time was decreased from an average of 70 minutes to approximately 35 minutes. A total of 65 (1.68%) intraoperative complications were recorded and the frequencies were in a significant decreasing trend. The rate of malalignment was in a decreasing trend and steady desired alignment (6°) was achieved at the 15th three-month interval. KSS and function scores increased from 87.4 to 91.5 and 92.6 to 96.8, respectively.

CONCLUSION

Although a surgeon may become competent with MIS-TKA and achieved the preliminary learning curve within one year, experience accumulation continuously improved technical proficiency in MIS-TKA. This study confirmed significant improvements in surgical skills, postoperative alignment, and patients' function over time.

Accuracy of medial-side cutting guide compared to anterior cutting guide in distal femoral osteotomy of total knee arthroplasty

INTRODUCTION

Minimally invasive surgery (MIS) in total knee arthroplasty has the benefits of less postoperative pain and a faster recovery time. An MIS instrument was designed to help surgeons perform this procedure under reduced visualization conditions. A medial cutting guide of the distal femur is used to cut the distal femoral bone without patella subluxation. This study aimed to compare the accuracy of the distal femoral bone cut between the medial and standard anterior cutting guides.

MATERIALS AND METHODS

Two orthopedic surgeons, who specialize in total knee arthroplasty and are familiar with both of these cutting guides, performed the procedures. Forty-eight synthetic saw bones were used, and five-degree valgus medial and anterior cutting guides were randomly assigned to the surgeons. After the osteotomies were performed, the synthetic saw bones were investigated via plain radiographs. Two independent radiologists measured the medial distal femoral angle (MDFA) and the posterior distal femoral angle (PDFA).

RESULTS

The MDFA in the medial cutting group was statistically significantly different from that of the anterior cutting group (94.18° ± 1.47° vs. 94.98° ± 1.14°, P = 0.041). However, the PDFA was not different between the two groups. Likewise, the number of outliers was not different between the groups when a ± 2° error was defined as an outlier (P = 0.609 for MDFA and P = 0.359 for PDFA). Moreover, a high degree of reliability was found in both MDFA and PDFA measurements (intraclass correlation coefficients = 0.813 and 0.824, respectively).

CONCLUSIONS

In this experimental study, the MIS medial cutting guide was less accurate than the standard cutting guide in the distal femoral cut.

Minimally invasive versus conventional approaches in total knee replacement/arthroplasty: A review of the literature

Background

Life expectancy lengthening and aging of population resulted in dramatically increase of patients with osteoarthritis. Total knee arthroplasty is widely used as the gold standard in order to relieve pain, correct deformity and restore function. A contemporary and controversial topic, is that of minimally invasive surgery for TKA. The minimally invasive approaches are based on the concept that they don't violate the extensor mechanism, resulting in earlier functional recovery, shorter hospital stay and enhanced patients' overall satisfaction. The most commonly used MIS approaches in TKA are the subvastus, midvastus and the quadriceps sparing. There is a debate regarding the efficacy and safety of these methods.

Objective

In this article we will review the current literature (randomized controlled trials and systematic reviews/meta-analyses) on MIS compared to traditional approach and analyse their clinical safety, efficacy and long-term results.

Design

Comparison of well-designed studies have tried to demonstrate the advantages/disadvantages, the clinical results and the complications of the MIS approaches compared to the MPP approach.

Results

MIS approaches seem to provide advantages in the immediate post-operative period accompanied by increased reports of complications. Consequently, further investigation based on large well-designed studies with long-term results are warranted to further clarify MIS effectiveness/safety.

Mid-term survivorship of cruciate-retaining versus posterior-stabilized total knee arthroplasty using modular mini-keel tibial implants

Background

Reports of diverse outcomes in modular mini-keel tibial componentry for total knee arthroplasty (TKA) have raised concerns about early aseptic loosening. Cruciate-retaining (CR) prostheses, using mini-keel implants, have yet to be reported and compared to posterior-stabilizing (PS) designs.

Methods

A retrospective, case-matched study of 91 consecutive TKAs (n = 46 CR; n = 45 PS prostheses), using modular mini-keel tibial componentry with a 45-mm drop down stem extension, was conducted. The Knee Society Score functional survey, radiographic analysis including alignment and periprosthetic radiolucency, TKA prosthesis longevity, and surgical complications were reported and compared between CR and PS groups.

Results

The Knee Society Score at 5-year follow-up averaged 81.67 ± 11.97 and 80.12 ± 14.16 in the CR and PS groups, respectively (p = 0.29). The femorotibial angle averaged 5.85° ± 2.62° and 5.85° ± 3.27° valgus in the CR and PS groups, respectively (p = 0.60). The average tibial component angle was 0.46° ± 1.6° and 0.61° ± 1.3° varus in the CR and PS groups, respectively (p = 0.30); posterior inclination averaged 2.28° ± 2.36° and 1.93° ± 2.72° in the CR and PS groups, respectively (p = 0.51). Radiolucency was noted in 17 zones of the CR group and in 9 zones of the PS group (p = 0.24). Three TKAs required further surgery: one locking plate fixation for a periprosthetic tibial fracture (PS group) and two revision TKAs (one CR infection and one PS fracture).

Conclusion

Modular mini-keel tibial components showed good reliability and results with both CR and PS prostheses in minimally invasive surgery TKA.

Comparison of Mini-Midvastus and Conventional Total Knee Arthroplasty with Clinical and Radiographic Evaluation: A Prospective Randomized Clinical Trial with 5-Year Follow-up

BACKGROUND

The main objective of this prospective randomized study was to compare the clinical and radiographic outcomes of the mini-midvastus (MMV) approach with the conventional approach for total knee arthroplasty at the 5-year follow-up.

METHODS

Ninety-seven patients (100 knees) with osteoarthritis were assigned to the MMV group or to a group receiving conventional total knee arthroplasty. Intraoperative and postoperative clinical data were collected. At 6 weeks and at 1, 2, and 5 years postoperatively, the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Oxford Knee Score (OKS), the Knee Society Score (KSS), and the Short Form (SF)-12 were completed. Radiographs of the knee were made preoperatively and at 1 day and 1 and 5 years postoperatively. Computed tomography (CT) scans were performed 2 years postoperatively.

RESULTS

In the MMV group, the mean skin incision was 2.5 cm shorter (p < 0.001) and the mean duration of the operation was 6 minutes longer than in the conventional total knee arthroplasty group (p < 0.05). Eight patients in the conventional group had a lateral parapatellar retinacular release compared with 1 in the MMV group; the difference was significant (p = 0.01). Three intraoperative complications, including 2 small lateral femoral condylar fractures and 1 partial patellar tendon laceration, occurred in the MMV group. Seven patients in the MMV group had postoperative blisters; all of them had a relatively large femoral component and 4 of them were large men. The radiographs and CT scans of the prostheses showed no significant differences between the MMV and conventional groups except for the posterior slope of the tibial component. In addition, no significance differences were detected between the groups with respect to the KOOS, OKS, KSS, and SF-12 scores determined at the 6-week and the 1, 2, and 5-year follow-up evaluations.

CONCLUSIONS

In the rehabilitation period and at the short and mid-term follow-up, no relevant clinical and radiographic differences were found between the MMV and the conventional approach for total knee arthroplasty, making the advantage of MMV total knee arthroplasty cosmetic. We discourage the use of the MMV approach in large male patients because of the increased number of intraoperative complications and skin blisters postoperatively.

LEVEL OF EVIDENCE

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

Quality of cementation in conventional versus minimally invasive total knee arthroplasty

PURPOSE

To review the immediate postoperative radiographs of 108 patients following conventional or minimally invasive total knee arthroplasty (TKA) to assess the quality of cementation in terms of cement voids and retained cement.

METHODS

Records of 20 male and 88 female consecutive patients aged 50 to 83 (mean, 67.5) years who underwent conventional TKA (n=56) or computer-assisted minimally invasive TKA (n=52) for osteoarthritis by a single senior surgeon were reviewed. Immediate postoperative radiographs were assessed by a single blinded assessor for the quality of cementation in terms of cement void and retained cement in different zones of the femoral, tibial, and patellar components along the prosthesis-bone interface using the Knee Society total knee arthroplasty roentgenographic evaluation and scoring system.

RESULTS

The 2 groups were comparable in terms of baseline demographics as well as cement void and retained cement on the femoral, tibial, and patellar components, except that in the minimally invasive group, cement void beneath the anterior flange of the femoral component was wider (0.32 vs. 0 mm, p=0.001), and retained cement in the posterior or lateral aspects of the tibial component was more common (50.0% vs. 28.6%, p=0.018).

CONCLUSION

Minimally invasive TKA resulted in a wider cement void beneath the anterior flange of the femoral component and a higher rate of retained cement around the tibial component.

Radiologic Outcomes According to Varus Deformity in Minimally Invasive Surgery Total Knee Arthroplasty

PURPOSE

To identify the accuracy of postoperative implant alignment in minimally invasive surgery total knee arthroplasty (MIS-TKA), based on the degree of varus deformity.

MATERIALS AND METHODS

The research examined 627 cases of MIS-TKA from November 2005 to December 2007. The cases were categorized according to the preoperative degree of varus deformity in the knee joint in order to compare the postoperative alignment of the implant: less than 5° varus (Group 1, 351 cases), 5° to less than 10° varus (Group 2, 189 cases), 10° to less than 15° varus (Group 3, 59 cases), and 15° varus or more (Group 4, 28 cases).

RESULTS

On average, the alignment of the tibial implant was 0.2±1.4°, 0.1±1.3°, 0.1±1.6°, and 0.3±1.7° varus, and the tibiofemoral alignment was 5.2±1.9degrees, 4.7±1.9°, 4.9±1.9°, and 5.1±2.0° valgus for Groups 1, 2, 3, and 4, respectively, in the preoperative stage, indicating no difference between the groups (p>0.05). With respect to the accuracy of the tibial implant alignment, 98.1%, 97.6%, 87.5%, and 86.7% of Groups 1, 2, 3, and 4, respectively, had 0±3° varus angulation, demonstrating a reduced level of accuracy in Groups 3 and 4 (p<0.0001). There was no difference in terms of tibiofemoral alignment, with 83.9%, 82.9%, 85.4%, and 86.7% of each group, respectively, showing 6±3° valgus angulation (p>0.05).

CONCLUSION

Satisfactory component alignment was achieved in minimally invasive surgery in total knee arthroplasty, regardless of the degree of varus deformity.

Effect of smoking and soft tissue release on risk of revision after total knee arthroplasty: a case- control study

Background

Increasing utilization of primary total knee arthroplasty (TKA) is projected to expand demand for revision TKA. Revision TKAs are procedurally complex and incur high costs on our financially constrained healthcare system. The purpose of this study was to use a case-control design to identify factors predisposing to revision TKA, particularly demographic, clinical and perioperative technical factors.

Methods

We conducted a case control study to investigate patient, surgical and perioperative factors associated with greater risk of revision TKA. We included patients who received TKA at a tertiary center between 1996 and 2009. Cases (patients that had primary and revision TKA) were matched to controls (patients with primary TKA that was not revised) in a 1:2 ratio and risk of revision examined using conditional logistic regression.

Results

We identified 146 cases and 290 controls. Patient factors independently associated with revision included male sex (OR 1.73; 95 % CI 1.06-2.81) and smoking (OR 2.87; 1.33-6.19). Older age was associated with decreased risk (OR 0.83 per 5-year increment; 95 % CI 0.75-0.92). Lateral release was the only technical factor associated with revision (OR 1.92; 1.07-3.43).

Conclusions

In this case control study younger patient age, male gender, soft tissue release and active smoking status were associated with increased revision risk. Although we do not know whether the risk of smoking arises from short- or long-term exposure, smoking cessation prior to TKA should be considered as an intervention for decreasing revision risk.

A comparison of registration errors with imageless computer navigation during MIS total knee arthroplasty versus standard incision total knee arthroplasty: a cadaveric study

Optimal component alignment in total knee arthroplasty has been associated with better functional outcome as well as improved implant longevity. The ability to align components optimally during minimally invasive (MIS) total knee replacement (TKR) has been a cause of concern. Computer navigation is a useful aid in achieving the desired alignment although it is limited by the error during the manual registration of landmarks. Our study aims to compare the registration process error between a standard and a MIS surgical approach. We hypothesized that performing the registration error via an MIS approach would increase the registration process error. Five fresh frozen lower limbs were routinely prepared and draped. The registration process was performed through an MIS approach. This was then extended to the standard approach and the registration was performed again. Two surgeons performed the registration process five times with each approach. Performing the registration process through the MIS approach was not associated with higher error compared to the standard approach in the alignment parameters of interest. This rejects our hypothesis. Image-free navigated MIS TKR does not appear to carry higher risk of component malalignment due to the registration process error. Navigation can be used during MIS TKR to improve alignment without reduced accuracy due to the approach.

A meta-analysis of minimally invasive and conventional medial parapatella approaches for primary total knee arthroplasty

PURPOSE

Minimally invasive surgical (MIS) approaches for total knee arthroplasty (TKA) have become increasingly popular for doctors and patients. They have argued that it decreases post-operative pain, accelerates functional recovery and increases patient satisfaction due to less injury. However, critics are concerned about TKA's possible effects on component position and with complications, considering the procedure's limited exposure. The purpose of this study was to summarise the best evidence in comparing the clinical and radiological outcomes between MIS and a conventional approach in TKA.

METHODS

Electronic databases were systematically searched to identify relevant randomised controlled trials (RCTs). Our search strategy followed the requirements of the Cochrane Library Handbook. Methodological quality was assessed, and data were extracted independently by two authors.

RESULTS

Thirty studies, including 2,536 TKAs, were reviewed: 1,259 minimally invasive and 1,277 conventional exposure TKAs. The results showed that while the MIS group had longer operation times and tourniquet times, it had superior outcomes in KSS (objective and total), range of motion, flexion range of motion, flexion 90° day, straight leg-raising day, total blood loss and decrease in haemoglobin. However, wound-healing problems occurred more frequently in the MIS group. There were no statistically significant differences in other clinical or radiological outcomes between the MIS and conventional groups in TKA.

CONCLUSION

The preliminary results indicate that the MIS approach provides an alternative to the conventional approach, with earlier rehabilitation but no malpositioning or severe complications. Wound-healing problems can be treated easily and effectively, and the risk also decreases as surgeons become more experienced, and more user-friendly instruments are invented. Potential benefits in medium- and long-term outcomes require larger, multicentre and well-conducted RCTs to confirm.

LEVEL OF EVIDENCE

Therapeutic study, Level II.

Mini-midvastus total knee arthroplasty in patients with severe varus deformity

Patients with severe varus deformity of the knee (≥15° varus) usually are not considered good candidates for minimally invasive total knee arthroplasty (TKA). The goal of this study was to retrospectively investigate outcomes in patients with severe varus deformity after minimally invasive TKA. A study group of 52 patients with a tibiofemoral mechanical axis of 195° or greater was compared with a matched control group of 55 patients with a tibiofemoral mechanical axis of less than 195°. Clinical and radiographic evaluations according to the American Knee Society rating system were obtained preoperatively and postoperatively, and postoperative patient satisfaction in the 2 groups was compared. All patients were followed at a mean of 3 years (range, 2-5 years). Preoperatively, clinical knee and function scores and range of motion were inferior in the study group compared with the control group (P<.001). However, at the latest follow-up, both groups of patients were satisfied with the clinical results, and no significant differences were found in the knee and function scores (P>.05). Radiographic evaluation showed no differences in the mechanical axis, femoral component valgus angle, and tibial component valgus angle, and all outliers of the radiographic parameters between the 2 groups postoperatively (P >.05). The study results showed that mini-midvastus TKA did not result in more inaccurate implant positioning in patients with severe varus deformity of the knee. The clinical outcome in the group with severe varus was comparable to that in the group with less severe varus

Results of the Oxford Phase 3 mobile bearing medial unicompartmental knee arthroplasty from an independent center: 467 knees at a mean 6-year follow-up: analysis of predictors of failure

A retrospective review of 467 Oxford UKAs was performed in 387 patients. Thirty-eight knees (8.1%) were revised to TKA at a mean of 49 months, most commonly for lateral compartment OA (47%). The 5-year cumulative survival using revision to TKA was 98.5%. Revisions required short stems in 26% and augments in 21% of cases. The mobile bearing dislocation rate was 0.64%. Correction of ≥3-5° from the preoperative alignment in a valgus direction was predictive of revision to TKA (P<.0001). Multivariate analysis revealed female gender (P=.002) also was associated with an increased risk of revision. Careful attention to the degree of mechanical axis correction with an overall maintained varus alignment may reduce revision rates for mobile bearing UKA.

Minimum 5-year Follow-up Results of Minimally Invasive Total Knee Arthroplasty Using Mini-Keel Modular Tibial Implant

Purpose

To evaluate the minimum 5-year mid-term clinical and radiological results of minimally invasive surgery total knee arthroplasty (MIS-TKA) using a mini-keel modular tibia component.

Materials and Methods

We retrospectively evaluated 254 patients (361 cases) who underwent MIS-TKA between 2005 and 2006. The latest clinical and radiological assessments were done in 168 cases that had been followed on an outpatient basis for more than 5 postoperative years. Clinical results were assessed using the Hospital for Special Surgery (HSS) score and Knee Society score. Radiological evaluation included measurements of knee alignment.

Results

The average postoperative knee range of motion and HSS score were 134.3°±12.4° and 92.7°±7.0°, respectively. The average postoperative femorotibial angle and tibial component alignment angle were 5.2°±1.7° valgus and 90.2°±1.6°, respectively. The average tibial component posterior inclination was 4.8°±2.1°. The percentage of cases with tibial component alignment angle of 90°±3° was 96.1%, and that with the femorotibial angle of 6°±3° valgus was 94.0%. Radiolucent lines were observed in 20 cases (12.0%): around the femur, tibia, and patella in 14 cases, 10 cases, and 1 case, respectively. However, they were less than 2 mm and non-progressive in all cases. The survival rate was 99.4% and there was no implant-related revision.

Conclusions

MIS-TKA using a mini-keel modular tibial plate showed satisfactory results, a high survival rate, and excellent clinical and radiological results in the mid-term follow-up.

Minimally invasive total knee arthroplasty; a pragmatic randomised controlled trial reporting outcomes up to 2 year follow up

BACKGROUND

We present a prospective, randomised, multi-surgeon, controlled trial comparing minimally invasive (MIS) and standard approach total knee arthroplasty (TKA).

METHODS

Participants underwent unilateral TKA. Patients were randomised to Bristol, quadriceps sparing MIS or standard medial parapatellar approaches. Length of stay with secondary outcome measures including knee range of movement, Oxford Knee Score (OKS), Western Ontario and McMaster Universities Arthritis Index (WOMAC) and American Knee Society Score (KSS) up to 2 years. Radiographic and post operative assessment was blinded.

RESULTS

86 patients (92 knees) participated in the study. Mean operative time between MIS and control groups was 95.5 (95% CI 90.0-101.0) and 94.8 (95% CI 88.2-101.4) minutes respectively. Mean readiness for discharge was shorter in the MIS group 4.5±1.5 (95% CI, 4.1-4.9) days versus 5.9±2.7 (95% CI, 5.1-6.7) days amongst controls (p=0.004). Patients in the MIS group had fewer complications (p=0.003). One patient developed a deep vein thrombosis (DVT) and one required revision surgery, both in the control group. 83 patients completed follow up to 2 years (40 MIS, 43 controls). Range of movement and other outcome measures improved up to 1 year post-operatively with no statistically significant differences between MIS and controls. We found no evidence of radiographic loosening in either group at the 2 year follow up.

CONCLUSIONS

MIS offers reduced length of stay and fewer complications for patients following TKR without evidence of component mal-alignment. Our findings of fewer systemic complications in MIS TKR patients warrant further future study.

LEVEL OF EVIDENCE

Level 1.

Web-based information on minimally invasive total knee arthroplasty

PURPOSE

To evaluate information available on the internet regarding minimally invasive total knee arthroplasty (TKA).

METHODS

The 3 most popular search engines (Google, Yahoo, and MSN) were used to search the keyword 'minimally invasive knee replacement'. The top 50 websites from each search engine were evaluated for authorship and contents; duplicate websites were not double-counted.

RESULTS

Of the 150 websites, 51% were authored by a hospital/university, 26% by private medical groups, 14% were news stories, and 9% were from orthopaedic industry sources. 73% offered the opportunity to make an appointment. 18% described the surgical technique, whereas only 9% explained patient eligibility. 25% described the risks, whereas only 3% made reference to peer-reviewed publications. >82% made specific claims regarding the advantages of minimally invasive surgery.

CONCLUSION

Most websites providing minimally invasive TKA information were insufficient in terms of explaining surgical technique, patient eligibility, and assoicated risks.

Faster recovery after minimally invasive surgery in total knee arthroplasty

PURPOSE

The aim of the study was to identify whether less soft tissue and muscle damage during surgery will allow faster recovery after total knee arthroplasty in comparison with the conventional technique. A limited medial parapatellar approach without tibial medial collateral ligament (MCL) desinsertion was compared with the conventional parapatellar approach.

METHODS

Three hundred patients were randomized either into the minimally invasive group (MIS group) or into the conventional group (CON group). The evaluation was based on the Knee Society Score, range of motion, blood loss, period of hospitalization and postoperative hemoglobin level.

RESULTS

The MIS group showed faster recovery with immediate postoperative full weight-bearing and shorter length of stay (5 vs 10 days). Comparable Knee Society Scores (87.5 vs 88), function scores (90) and alignment (5.5° vs 5.2°) between the CON and MIS group were observed at a follow-up of 24 months. No increase in operative times (52 vs 51 min tourniquet time) or no complications were observed. Reduced blood loss was observed in the MIS group (590 vs 989 ml).

CONCLUSION

The MCL sparing limited medial parapatellar approach allows good surgical exposure, easy extension proximally if necessary, contained closure after surgery with less bleeding, faster recovery, full weight-bearing without aid and most importantly no radiological malalignment.

LEVEL OF EVIDENCE

Therapeutic study, Level II.

Minimally invasive and computer-assisted total knee arthroplasty versus conventional technique: a prospective, randomized study

We conducted a prospective, randomized study to compare the short-term results of minimally invasive and computer-assisted total knee arthroplasty (MICA-TKA) with those of conventional total knee arthroplasty (C-TKA) for 12-month follow-up. A total of 87 subjects who met the inclusion and exclusion criteria of the study were prospectively randomized consecutively into two groups: the C-TKA group (Group A, n = 44) and the MICA-TKA technique (Group B, n = 43). All the operations were performed by the same senior surgeon. Before surgery and at follow-up, patients were evaluated by the same observer. Tourniquet time as well as total blood loss was compared. Knee Society scores (KSSs), Knee Society functional scores (KSFSs), range of motion (ROM), and radiographic results were assessed and reported preoperatively and at 12-month follow-up. Of these patients, 82 (Group A 42; Group B 40) were available for 12-month evaluation. The two groups were found to be similar in terms of coronal mechanical axis. Similarly, the femoral rotational profile revealed that the prosthesis in Group A was implanted with similar internal rotation to Group B. The average blood loss in patients of Group B was significantly reduced as compared to patients of Group A. No significant difference was detected in terms of tourniquet time. Clinical results in Group B, with regard to ROMs and KSSs, as well as KSFSs were significantly superior to that in Group A. Based on the results obtained from this study, it is demonstrated that MICA-TKA leads to a similarly accurate restoration of leg alignment and component orientation compared to the C-TKA. Moreover, MICA-TKA produces superior clinical results to that of C-TKA. However, there is clearly a need for additional high-quality clinical trials with long-term follow-up to confirm the clinical benefits of MICA-TKA.

Why are total knees failing today? Etiology of total knee revision in 2010 and 2011

Revision knee data from six joint arthroplasty centers were compiled for 2010 and 2011 to determine mechanism of failure and time to failure. Aseptic loosening was the predominant mechanism of failure (31.2%), followed by instability (18.7%), infection (16.2%), polyethylene wear (10.0%), arthrofibrosis (6.9%), and malalignment (6.6%). Mean time to failure was 5.9 years (range 10 days to 31 years). 35.3% of all revisions occurred less than 2 years after the index arthroplasty, 60.2% in the first 5 years. In contrast to previous reports, polyethylene wear is not a leading failure mechanism and rarely presents before 15 years. Implant performance is not a predominant factor of knee failure. Early failure mechanisms are primarily surgeon-dependent.

The John Insall award: no benefit of minimally invasive TKA on gait and strength outcomes: a randomized controlled trial

BACKGROUND

While some clinical reports suggest minimally invasive surgical (MIS) techniques improve recovery and reduce pain in the first months after TKA, it is unclear whether it improves gait and thigh muscle strength.

QUESTIONS/PURPOSES

We hypothesized TKA performed through a mini-subvastus approach would improve subjective and objective and subjective function compared to a standard medial parapatellar approach 2 months after surgery.

METHODS

We randomized 40 patients into two groups using either the mini-subvastus approach or standard medial parapatellar approach. Patients were evaluated preoperatively and 2 months after surgery. We assessed subjective functional outcome and quality of life (QOL) using routine questionnaires (SF-12, Knee Society Score [KSS], Knee Injury and Osteoarthritis Outcome Score [KOOS], UCLA activity, patient milestone diary of activities). We determined isometric strength of the thigh muscles and assessed gait with a three-dimensional (3-D) analysis during level walking and stair climbing.

RESULTS

We observed improvements from preoperatively to 2 months postoperatively in functional scores, QOL, and knee kinematic and kinetic gait parameters during level and stair walking. Isometric quadriceps strength increased in both groups, although remaining lower when compared to sound limbs. We found no differences between the groups in KSS, SF-12, KOOS, UCLA activity, patient milestone diary of activities, isometric quadriceps strength, or 3-D gait parameters, except a marginally higher speed of stair ascent in the MIS group.

CONCLUSIONS

Our observations suggest an MIS approach does not confer a substantial advantage in early function after TKA.

LEVEL OF EVIDENCE

Level I, therapeutic study. See Instructions to Authors for a complete description of levels of evidence.

Computer-assisted total knee arthroplasty is currently of no proven clinical benefit: a systematic review

BACKGROUND

Navigated total knee arthroplasty (TKA) may improve coronal alignment outliers; however, it is unclear whether navigated TKA improves the long-term clinical results of TKA.

QUESTIONS/PURPOSES

Does the literature contain evidence of better long-term function and lower revision rates with navigated TKA compared with conventional TKA?

METHODS

A systematic literature review was conducted of navigated TKA reviewing articles related to coronal alignment, clinical knee and function scores, cost, patient satisfaction, component rotation, anteroposterior and mediolateral stability, complications, and longer-term reports.

RESULTS

Coronal plane alignment is improved with navigated TKA with fewer radiographic outliers. We found limited evidence of improvements in any other variable, and function was not improved. The duration of surgery is increased and there are unique complications related to navigated TKA. The long-term benefits of additional increase in accuracy of alignment are not supported by any current evidence.

CONCLUSIONS

The findings in reports of navigated TKA should be interpreted with caution. There are few short- and medium- and no long-term studies demonstrating improved clinical outcomes using navigated TKA. Despite substantial research, contradictory findings coupled with reservations about the cost and efficacy of the technology have contributed to the failure of computer navigation to become the accepted standard in TKA. Longer-term studies demonstrating improved function, lower revision rates, and acceptable costs are required before navigated TKA may be widely adopted. In the future, with improvements in study design, methodology, imaging, navigation technology, newer functional outcome tools, and longer-term followup studies, we suspect that navigated TKA may demonstrate yet unrecognized benefits.

A prospective randomised study of minimally invasive midvastus total knee arthroplasty compared with standard total knee arthroplasty

INTRODUCTION

Proposed advantages of minimally invasive surgery include shorter hospital stay, less blood loss, and a greater range of motion but potential concerns are raised about both prolonged learning curves and a compromise in exposure leading to implant malposition.

PATIENTS AND METHODS

This powered study evaluates the outcomes of 80 patients randomised to have mini-midvastus (MMV) approach or standard medial parapatellar (MPP) approach. Rehabilitation protocols and discharge criteria were standardised. Patients were discharged home directly, capable of safe independent care. Validated outcome measures were recorded post-operatively at intervals up to 1 year. Independent, blinded review of post-operative x-rays was obtained.

RESULTS

Length of stay was similar in the MMV and MPP groups (median 3.73 days vs. 3.75 days). No statistically significant differences were detected in either the demographic data or any intra-operative variable apart from blood loss and incision length. No statistically significant difference in clinical outcome measures (Oxford/Knee Society Scores) or radiographic analysis was observed.

CONCLUSION

The MMV approach does not appear to confer any clinically significant benefit apart from a smaller surgical scar, compared to the MPP surgical technique. Level of evidence I: randomised control trial. R.E.C. 040301.

Is computer-assisted surgery in total knee arthroplasty as accurate as it can be?

Three hundred and eighty computer-assisted total knee arthroplasty cases were reviewed for accuracy of mechanical alignment. The 331 patients in the first set, designated Group A, showed a consistent valgus error of 1° from neutral alignment. It was hypothesized that a manual 1° varus correction during femur resection would yield a significantly greater level of accuracy in the second set of 49 patients, designated Group B. A mechanical alignment of ±3° was achieved in 91% of the uncalibrated Group A patients, which was significantly lower (p = 0.035) than the rate of 98% achieved in the calibrated Group B. Further statistical analysis of the data showed the time expenditure was not significantly changed once a new target value was recalibrated. By quantifying mean errors of measures at an early timeframe, enhanced accuracy in CAS can be achieved.

A meta-analysis of randomised controlled trials comparing the clinical and radiological outcomes following minimally invasive to conventional exposure for total knee arthroplasty

Proponents of minimally invasive total knee arthroplasty (TKA) state accelerated patient recovery and increased patient satisfaction as advantages. However, retractors state a greater incidence of iatrogenic nerve injury, implant mal-positioning and increased rates of revision. This study compares the clinical and radiological outcomes of minimally invasive and conventional exposure TKA using a meta-analysis. A search of published and unpublished literature was performed. Eighteen studies including 1582 TKAs were reviewed: 822 minimally invasive versus 760 conventional exposure TKAs. The findings of this study suggest that whilst incision length was significantly smaller in MIS (p=0.001), and flexion range of motion was significantly greater following MIS (p=0.01), there was no statistically significant differences in all other clinical or radiological outcomes between MIS or conventional approach TKA surgery (p>0.05).

[Total knee arthroplasty for rheumatoid arthritis]

A total of 150,000 primary total knee arthroplasties are performed in Germany each year. There is only a limited amount of evidence-based data available on possible surgery-related differences between osteoarthritis (OA) and rheumatoid arthritis (RA) of the knee joint. The following review summarizes the recent literature on total knee arthroplasty with a focus on special features of RA patients.

Is minimally invasive total knee arthroplasty associated with lower costs than traditional TKA?

BACKGROUND

Studies of minimally invasive surgery (MIS) approaches to TKA have shown decreased postoperative pain, earlier return to function, and shorter lengths of stay in the hospital. However, it is unclear whether these differences translate into decreased costs or charges associated with care.

QUESTIONS/PURPOSES

We asked whether a minimally invasive approach to TKA is associated with lower inpatient charges and direct inpatient costs than the traditional approach.

PATIENTS AND METHODS

We retrospectively reviewed one high-volume arthroplasty surgeon's first 100 minimally invasive TKAs with the last 50 traditional TKAs with respect to all perioperative inpatient medical and billing records. Total charges minus implants (which were excluded across groups), total direct costs, and individual cost centers were analyzed.

RESULTS

The mean nonimplant total charge was less for patients receiving a minimally invasive TKA than a traditional TKA ($13,505 versus $14,552). With the numbers available, there was a trend for lower mean direct cost for minimally invasive TKA ($6156) versus traditional TKA ($6410).

CONCLUSIONS

The total inpatient charges associated with a minimally invasive TKA were less than those associated with a traditional TKA; however, the magnitude of the difference (7.2%) was modest, and there was no reduction in direct hospital costs. Other studies will need to determine whether any economic benefits associated with minimally invasive TKA accrue after discharge. The decision regarding whether to perform minimally invasive TKA should be made on clinical grounds, as the medical-economic case on the inpatient side is not compelling.

Complications after minimally invasive total knee arthroplasty as compared with traditional incision techniques: a meta-analysis

The primary objective of our meta-analysis was to compare the incidence of complications between minimally invasive surgery and standard total knee arthroplasty (TKA) approaches. We reviewed randomized controlled trials comparing minimally invasive TKA to standard TKA. After testing for publication bias and heterogeneity, the data were aggregated by random effects modeling. Our primary outcome was the number of complications. Our secondary outcomes were alignment outliers, Knee Society Function scores, and Knee Society Knee scores. The combined odds ratios for complications for the minimally invasive surgery group and alignment outliers were 1.58 (95% confidence interval, 1.01-2.47; P < .05) and 0.79 (95% confidence interval, 0.34-1.82; P = .58), respectively. The standard difference in means for Knee Society scores was no different between groups. Minimally invasive knee surgery should be approached with caution.

Anterolateral approach with tibial tubercle osteotomy versus standard medial approach for primary total knee arthroplasty: does it matter?

Background

The purpose of this prospective consecutive multicenter study was to investigate whether the type of surgical approach (medial parapatellar (MPA) or lateral parapatellar with tibial tubercle osteotomy (TubOT)) influences the early clinical and radiological outcomes of primary total knee arthroplasty (TKA).

Methods

Ligament balancing primary TKA with a rotating platform was performed in 143 knees (m:w = 1:1.6; mean age 69 ± 8 years). The TKA was done by a lateral parapatellar subvastus approach with stepcut osteotomy of the tibial tubercle (53%; n = 76, group A) or medial parapatellar approach (47%; n = 67, group B). The outcome was assessed at 1 and 2 years postoperatively by the American Knee Society score (KSS) and the knee society total knee arthroplasty roentgenographic evaluation and scoring system (TKA-RESS). The patient's pain level and satisfaction was noted by a visual analogue scale (VAS). Data were analyzed by an independent statistician with a level of significance of p < 0.05. The Wilcoxon two sample test (two-sided) was used to investigate differences of patients between group A and B pre- and postoperatively. The paired t-test was used to evaluate differences over course of time within each group. For comparison of radiological alignment a Chi²-test was performed.

Results

Although having a lower degree of preoperative flexion (112° ± 15° versus 115° ± 15°) patients in group A showed a significantly (p = 0.027) higher degree of flexion (118° ± 10°) at their last follow-up than patients in group B (114° ± 10°). Patients in group A showed a significantly better mean VAS pain (p = 0.0001) and satisfaction (p = 0.0058) at 2 years follow-up. The pain free walking distance was significantly (p = 0.036) longer for group A than group B. Patients treated with a lateral approach were significantly more stable in terms of valgus stress (p = 0.049). The Knee society score was significantly (p = 0.0009) higher at two years follow up in group A compared to group B. The postoperative mechanical alignment and positioning of the prosthesis were not significantly different. Patients in group B presented with significantly (p = 0.0017) more tibial radiolucencies (> 2 mm) at their last follow-up than patients in group A. There was no prosthesis related revision in either group. The revision rate in group A (4%) was higher than in group B (1.5%), which was mainly due to two cases of traumatic secondary displacement of the tibial tubercle and need for refixation.

Conclusions

The TubOT led to slightly better functional results and less pain two years after primary TKA. It is however not clear if the improved outcome can outweigh the longer operation time and higher risk of early complications and revisions. Long-term studies are necessary to show whether there is any difference in prosthesis longevity between both types of approach.

Does minimally invasive surgery improve short-term recovery in total knee arthroplasty?

BACKGROUND

Concerns have been raised regarding minimally invasive surgery (MIS) and its possible effect on postoperative functional recovery, complications, and survival rate after TKA.

QUESTIONS/PURPOSES

We specifically asked whether MIS TKA would be associated with (1) increased operative time, (2) reduced blood loss, (3) shortened hospital stay, (4) faster recovery of ROM, (5) higher knee scores, (6) inferior component positioning, and (7) increased complications.

METHODS

We performed a systematic literature search of randomized controlled trials between minimally invasive and standard approaches in TKA that compared operative time, blood loss, ROM, knee scores, component positioning, and complications. We conducted a systematic review and meta-analysis of 13 trials published from 2007 to 2009 of MIS versus standard TKA.

RESULTS

Patients in the MIS group had longer operating times (10-19 minutes). Mean Knee Society scores were better after MIS than after the standard procedure at 6 and 12 weeks postoperatively, but not after 6 months. Improvement in ROM occurred more rapidly in the MIS group 6 days after TKA but later improvements are not clearly documented. We identified no differences between minimally invasive and standard approaches regarding the short-term overall complications and alignment of femoral and tibial components. However, wound healing problems and infections occurred more frequently in the MIS group.

CONCLUSIONS

MIS leads to faster recovery than conventional surgery with similar rates of component malalignment but is associated with more frequent delayed wound healing and infections. Potential benefits in long-term survival rate and functional improvement require additional investigation. Level of Evidence Level II, therapeutic study (systematic review). See the Guidelines for Authors for a complete description of levels of evidence.