Quadriceps sparing total knee replacement. The initial experience with results at two to four years

Minimally invasive surgery total knee arthroplasty is less popular, but the prosthesis designed specifically for MIS provides good survival and PROMs with a minimum follow-up of 10 years

BACKGROUND

The concept of minimally invasive surgery (MIS) was introduced in total knee arthroplasty (TKA) in the late 1990s. The number of MIS TKAs has clearly decreased in recent years. An implant designed specifically for MIS TKA has been used all over the world, but there are no reports of long-term postoperative results. The purpose of this study was to characterize long-term clinical results with a minimum follow-up of 10 years.

METHODS

This retrospective study included 109 consecutive patients with 143 NexGen CR-Flex prostheses, which are MIS tibial component prostheses designed specifically for MIS TKA. Twelve-year survival analysis was performed using Kaplan-Meier method. Revision surgery for any reason was the endpoint. Long-term clinical and radiographic results of 74 knees (55%) in 60 patients with more than 10 years of follow-up were analyzed.

RESULTS

The cumulative survival rate of the single-radius posterior-stabilized TKA of 74 knees was 94.7% (95% confidence interval, 90-99%) at 12 years after surgery. Seven knees (9%) required additional surgery during the 10-year follow-up because of periprosthetic infections. Mean postoperative Knee Society knee score and functional score were 91 and 74 points, respectively. There were no cases of prosthesis breakage, polyethylene wear, or aseptic loosening of the prosthesis.

CONCLUSION

The prosthesis designed specifically for MIS TKA is associated with good survival and clinical results with a minimum follow-up of 10 years, even though MIS TKA has become less popular.

LEVEL OF EVIDENCE

III.

Quadriceps-sparing versus traditional medial parapatellar approaches for total knee arthroplasty: a meta-analysis

Background

There is still controversy regarding whether Quadriceps-sparing (QS) approach for total knee arthroplasty (TKA) lead to better earlier recovery as well as compromising low limb alignment and prosthesis position compared with conventional medial parapatellar (MP) approach. To overcome the shortcomings and inaccuracies of single studies, the clinical outcomes and radiographic assessments of QS approach and MP approach were evaluated through meta-analysis.

Methods

We performed this meta-analysis according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. A literature search was conducted in the PubMed, EMBase, Cochrane Collaboration Library and Web of Science databases. Our search strategy followed the requirements of the Cochrane Library Handbook. The study selection, data extraction and assessment of methodological quality were independently completed by four authors. And subgroup analysis and publication bias were also performed in the study.

Results

Eight prospective randomized controlled trials (RCTs) and eight retrospective studies were identified. Overall meta-analysis and subgroup meta-analysis of RCTs identified the QS approach mainly was associated with increased Knee Society function score beyond 24 months postoperatively (weighted mean difference [WMD] 1.78, P = 0.0004) (WMD 1.86, P = 0.0002), and improved range of motion 1–2 weeks postoperatively (WMD 5.84, P < 0.00001) (WMD 4.87, P = 0.002). Besides, lower visual analogue scale on postoperative day 1 (WMD -0.91, P = 0.02), shorter hospital stay (WMD -0.88, P = 0.02) and shorter incision (extension) (WMD -4.62, P < 0.00001) were indicated in overall meta-analysis. However, surgical and tourniquet time was significantly longer in QS group by both overall and subgroup meta-analysis.

Conclusions

QS approach may accelerate early recovery without increasing the risk of malalignment of low limb and malposition of prosthesis.

Minimally invasive total knee replacement: techniques and results

In this review, we outlined the definition of minimally invasive surgery (MIS) in total knee replacement (TKR) and described the different surgical approaches reported in the literature. Afterwards, we went through the most recent studies assessing MIS TKR. Next, we searched for potential limitations of MIS knee replacement and tried to answer the following questions: Are there selective criteria and specific patient selection for MIS knee surgery? If there are, then what are they? After all, a discussion and conclusion completed this article. There is certainly room for MIS or at least less invasive surgery for appropriate selected patients. Nonetheless, there are differences between approaches. Mini-medial parapatellar is easy to master, quick to perform and potentially extendable, whereas mini-subvastus and mini-midvastus are trickier and require more caution related to risk of haematoma and vastus medialis oblique (VMO) nerve damage. Current evidence on the safety and efficacy of mini-incision surgery for TKR does not appear fully adequate for the procedure to be used without special arrangements for consent and for audit or continuing research. There is an argument that a sudden jump from standard TKR to MIS TKR, especially without computer assistance such as navigation, patient-specific instrumentation or robotic, may breach a surgeon's duty of care towards patients because it exposes patients to unnecessary risks. As a final point, more evidence is required on the long-term safety and efficacy of this procedure which will give objective shed light on real benefits of MIS TKR.

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.

Comparison of Quadriceps-Sparing and Medial Parapatellar Approaches in Total Knee Arthroplasty: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

The quadriceps-sparing (QS) technique for total knee arthroplasty (TKA) was introduced to improve outcomes associated with the medial parapatellar (MP) approach. There is no clear consensus on what advantages, if any, QS provides.

METHODS

We performed a meta-analysis of randomized controlled trials (RCTs) comparing the QS and MP techniques. PubMed, Ovid, and Scopus were assessed for relevant literature. Long-term (primary) outcomes and short-term (secondary) outcomes from 8 RCTs (579 TKAs) were analyzed using OpenMetaAnalyst (2016).

RESULTS

The QS approach did not demonstrate clinically significant advantages, but was associated with statistically and clinically significant increases in the primary outcomes of femoral (odds ratio [OR] 4.92, P = .005), tibial (OR 4.34, P = .01), and mechanical axis outliers (OR 4.77, P = .004). Secondary outcome assessments demonstrated increased surgical (mean differences [MD] 19.54, P < .001) and tourniquet time (MD 23.30, P < .001) for QS. Although statistically significant advantages for QS were identified in Knee Society Function scores at 1.5-3 months (MD 2.31, P = .004) and 2 years (MD 1.86, P < .001), these were not clinically significant (fell below the 6-point minimal clinically important difference).

CONCLUSION

The QS approach to TKA fails to demonstrate clinically significant advantages, but shows increased malalignment. This increased incidence of implant malalignment may predispose QS patients to early prosthesis failure. Because the QS approach may increases the risk of malalignment while providing no clear benefit compared to MP, we recommend against the routine use of the QS TKA approach.

Clinical Considerations for the Use Lower Extremity Arthroplasty in the Elderly

There is an increase in the aging population that has led to a surge of reported cases of osteoarthritis and a greater demand for lower extremity arthroplasty. This article aims to review the current treatment options and expectations when considering lower extremity arthroplasty in the elderly patient with an emphasis on the following subjects: (1) updated clinical guidelines for the management of osteoarthritis in the lower extremity, (2) comorbidities and risk factors in the surgical patient, (3) preoperative evaluation and optimization of the surgical patient, (4) surgical approach and implant selection, and (5) rehabilitation and life after lower extremity arthroplasty.

Malalignment and malposition of quadriceps-sparing approach in primary total knee arthroplasty: a systematic review and meta-analysis

Background

Quadriceps-sparing (QS) approach is considered to be the most minimally invasive surgery for total knee arthroplasty (TKA). We perform this meta-analysis to evaluate whether malalignment and malposition are more biased towards the QS approach compared to the traditional medial parapatellar (MP) approach, which is still controversial.

Methods

According to the PRISMA guidelines, a comprehensive search was conducted in the databases of PubMed, the Cochrane library, and Embase. Relevant measures were extracted independently by two investigators.

Results

Five randomized controlled trials (RCTs) and eight retrospective studies including a total of 1261 cases were identified. The QS approach was associated with more outliers of hip-knee-ankle (HKA) angle (p = 0.03), coronal tibial component angle (p = 0.03), and femoral notch (p = 0.05). However, the differences of the outlier of the coronal femoral component angle between the two groups were not statistically significant.

Conclusions

This meta-analysis indicates that the QS approach is related to the high risk of malalignment and malposition. However, different studies reported different indicators resulting in small samples for analyzing the radiological outcomes. In addition, both of the relatively long learning curve and the present instruments might increase the risk of malalignment and malposition of the QS approach, which needs further study and improvement.

Minimally invasive surgery (MIS) for total knee replacement; medium term results with minimum five year follow-up

BACKGROUND

MIS TKA has been shown to offer a reduced in-patient stay, but no clinical difference at two years. Whilst there may be a benefit from earlier discharge, we need to ensure that there are no detrimental effects in the medium and long-term following MIS-TKA. To report the mid-term result from a prospective randomised controlled trial (RCT) comparing MIS-TKA with standard approach for TKA.

METHODS

Using knee score questionnaires, we collected patient reported outcome measures (PROMs) regarding pain and function. Sixty-six patients (from an eligible cohort of 83 patients) completed the mid-term postal follow-up.

RESULTS

There was no significant difference between groups for change in score from pre-operative to final follow-up in all three PROMs. Mean MIS and standard group improvement was: AKSS 53 and 51 (p=0.7644), OKS 15 and 16 (p=0.2341) or WOMAC 15 and 15 (p=0.9900) respectively. Both groups showed improvement in pain and function with no significant difference between groups. There was no difference between groups for revision due to malalignment at a mean six year follow-up.

CONCLUSIONS

In addition to the early benefits regarding hospital stay and complications, we have found that at a mean of six years there was no increase in malalignment, pain or function with MIS techniques.

10-Year patient satisfaction compared between computer-assisted navigation and conventional techniques in minimally invasive surgery total knee arthroplasty

BACKGROUND

Both minimally invasive surgery (MIS) and computer-assisted surgery (CAS) in total knee arthroplasty have been scientifically linked with surgical benefits. However, the long-term results of these techniques are still controversial. Most surgeons assessed the surgical outcomes with regard to knee alignment and range of motion, but these factors may not reflect subjective variables, namely patient satisfaction.

PURPOSE

To compare satisfaction and functional outcomes between two technical procedures in MIS total knee arthroplasty, namely computer-assisted MIS and conventional MIS procedure, operated on a sample group of patients after 10 years.

METHODS

Seventy cases of posterior-stabilized total knee prostheses were implanted using a computer-assisted system and were compared to 74 cases of matched total knee prostheses of the same implant using conventional technique. Both groups underwent arthrotomy by 2 cm limited quadriceps exposure minimally invasive surgery (2 cm Quad MIS). At an average of 10 years after surgery, self-administered patient satisfaction and WOMAC scales were administered and analyzed.

RESULTS

Demographic data of both groups including sex, age, preoperative WOMAC and post-operative duration were not statistically different. Post-operative WOMAC for the computer-assisted group was 38.94 ± 5.68, while the conventional one stood at 37.89 ± 6.22. The median of self-administered patient satisfaction scales of the computer-assisted group was 100 (min37.5-max100), while the conventional one was 100 (min25-max100). p Value was 0.889. There was one re-operative case in the conventional MIS group due to peri-prosthetic infection which was treated with debridement, polyethylene exchanged and intravenous antibiotics.

CONCLUSIONS

The 10-year outcomes of computer-assisted MIS total knee arthroplasty are not superior to that of the conventional MIS technique in function and patient satisfaction. 10 years may not be enough to show the difference between these two techniques.

Minimally invasive navigation-assisted versus conventional total knee arthroplasty: a meta-analysis

PURPOSE

It is unclear whether the minimally invasive navigation-assisted (MINA) or conventional (CONv) approach for primary total knee arthroplasty (TKA) leads to better clinical and radiographic outcomes. This meta-analysis compared the clinical and radiographic outcomes of the MINA and CONv approaches after primary TKA. It was hypothesized that there was no difference in clinical and radiographic outcomes between the two surgical approaches for primary TKA.

METHODS

This meta-analysis reviewed all studies that compared surgical time, incision length, flexion range of motion (ROM), Knee Society Score ( KSS), coronal mechanical axis (CMA), and coronal femoral component angle (CFCA) with various measurement tools, from direct interview to plain radiography, between the MINA and CONv approaches.

RESULTS

Five studies met the inclusion/exclusion criteria for the meta-analysis. The findings of this study suggest that surgical time (95 % CI -18.51 to 39.09; n.s.), KSS (95 % CI -8.55 to 30.84; n.s.), CMA (95 % CI -1.01 to 0.54; n.s.), and CFCA (95 % CI -0.91 to 2.97; n.s.) were similar between the two surgical approaches, whereas incision length (95 % CI -5.18 to -3.69; P < 0.001) was significantly shorter in the MINA approach and flexion ROM (95 % CI 14.26-19.01; P < 0.001) was significantly greater in the MINA approach.

CONCLUSIONS

There were no significant differences in clinical and radiographic outcomes, including surgical time, KSS, CMA, and CFCA, in patients who underwent MINA and CONv approach for primary TKA, but the MINA approach resulted in a slightly shorter incision length and increased flexion ROM than the CONv approach. Therefore, if particular attention has to be paid to patient's selection with appropriate counselling and surgeon's experience, MINA approach can provide early clinical benefit when compared with CONv approach. Besides, orthopaedic surgeons need to master the MINA and CONv approaches because both approaches have similar clinical and radiographic outcomes.

LEVEL OF EVIDENCE

Therapeutic study, Level II.

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.

Minimally invasive knee arthroplasty: An overview

Minimally invasive surgery (MIS) for arthroplasty of the knee began with surgery for unicondylar knee arthroplasty (UKA). Partial knee replacements were designed in the 1970s and were amenable to a more limited exposure. In the 1990s Repicci popularized the MIS for UKA. Surgeons began to apply his concepts to total knee arthroplasty. Four MIS surgical techniques were developed: quadriceps sparing, mini-mid vastus, mini-subvastus, and mini-medial parapatellar. The quadriceps sparing technique is the most limited one and is also the most difficult. However, it is the least invasive and allows rapid recovery. The mini-midvastus is the most common technique because it affords slightly better exposure and can be extended. The mini-subvastus technique entirely avoids incising the quadriceps extensor mechanism but is time consuming and difficult in the obese and in the muscular male patient. The mini-parapatellar technique is most familiar to surgeons and represents a good starting point for surgeons who are learning the techniques. The surgeries are easier with smaller instruments but can be performed with standard ones. The techniques are accurate and do lead to a more rapid recovery, with less pain, less blood loss, and greater motion if they are appropriately performed.

Comparison of the quadriceps-sparing and subvastus approaches versus the standard parapatellar approach in total knee arthroplasty: a meta-analysis of randomized controlled trials

Background

The quadriceps-sparing and subvastus approaches are two of the most commonly used minimally-invasive approaches in total knee arthroplasty (TKA). However, the conclusion among studies still remains controversial. The purpose of this meta-analysis was to compare the clinical efficacy of the subvastus and quadriceps-sparing approaches with the standard parapatellar approach in TKA.

Methods

Randomized controlled trials (RCTs) comparing the quadriceps-sparing or subvastus approach with the standard parapatellar approach was identified in the databases of PubMed, the Cochrane library, EMBASE and Web of Science up to July 2014. Two authors extracted the following data: the basic characteristics of patients, the methodological quality and clinical outcomes from the included RCTs independently. RevMan 5.2.7 software was used for meta-analysis.

Results

A total of 19 RCTs (1578 patients) were included for meta-analysis. The results suggested that the quadriceps-sparing approach showed better outcomes in knee society score (KSS) and visual analog score (VAS), but this approach required a longer operative time than the standard parapatellar approach. There were no differences in total complications, wound infection, deep vein thrombosis, blood loss and hospital stay between the quadriceps-sparing and standard approaches. The subvastus approach showed better outcomes in VAS, knee range of motion (ROM), straight leg raise and lateral retinacular release than the standard parapatellar approach. There were no differences in KSS, total complication, wound infection, deep vein thrombosis, blood loss and hospital stay between the quadriceps-sparing and standard approaches.

Conclusions

The current evidence showed that, when compared with the standard parapatellar approach, the quadriceps-sparing approach was associated with better outcomes in KSS and VAS but required a longer operative time, and the subvastus approach was associated with better outcomes in VAS, ROM, straight leg raise and lateral retinacular release.

Are There Any Clinical and Radiographic Differences Between Quadriceps-sparing and Mini-medial Parapatellar Approaches in Total Knee Arthroplasty After a Minimum 5 Years of Follow-up?

BACKGROUND

Although the early clinical outcomes of total knee arthroplasty (TKA) using minimally invasive surgery techniques have been widely described, data on the mid- to long-term outcomes are limited. We designed a retrospective study to compare the two most common TKA techniques - The modified quadriceps-sparing (m-QS) approach and the mini-medial parapatellar (MMP) approach - In terms of the clinical and radiographic parameters, over a minimum follow-up period of 5 years.

METHODS

The m-QS approach was used in 31 knees and the MMP approach, in 36 knees. Knees in both groups were compared for component position and alignment, knee alignment, length of the skin incision, range of motion, Visual Analog Scale score, muscle torques, Knee Society Score, Western Ontario and McMaster Universities Osteoarthritis Index, and number of complications.

RESULTS

There were no major intergroup differences in any of the clinical and radiographic outcomes assessed at the final follow-up examination.

CONCLUSIONS

On the basis of numbers studied, the m-QS group, which requires more technique, showed equivalent results with the MMP group in the postoperative 5 years. Preservation of the extensor mechanism in the m-QS approach could not ensure any improvement in the clinical outcomes during the mid-term follow-up duration.

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

Total knee arthroplasty performed with either a mini-subvastus or a standard approach: a prospective randomized controlled study with a minimum follow-up of 2 years

BACKGROUND

There is currently a trend toward minimally invasive total knee arthroplasty (TKA) to decrease the morbidity related to the standard approach. The aim of our study was to clarify whether the mini-subvastus surgical had an advantage over the standard in term of pain level, blood loss, and postoperative recovery, whether the mini-subvastus surgical was prone to radiographic malalignment, prolonged operative time, and increased complications.

METHODS

In a prospective randomized study, we compared the clinical and radiological results of primary TKA using a mini-subvastus approach or a standard approach in 68 patients. The mini-subvastus approach was used on 35 patients (group I) and the standard approach on 33 patients (group II).

RESULTS

The mean follow-up was 28 months (range 24-36 months). Patients in group I had less blood loss and better visual analogue scale score at 1 day postoperatively. They achieved active straight leg raise earlier and underwent less lateral retinacular releases. The mean Knee Society function score, Oxford knee score, and range of movement were significantly better in group I up to 9 months after surgery (all, p < 0.05). However, there were no significant differences in these parameters between the groups at final follow-up. Reduced access and visibility in group I prolonged tourniquet time by an average of 22 min and resulted in five technical errors on radiographic evaluation.

CONCLUSIONS

Patients can receive marked but temporary benefits from the mini-subvastus technique, with a definite cost: that of component malposition and prolongation of operative time.

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.

Comparison of the clinical and radiological outcomes of three minimally invasive techniques for total knee replacement at two years

Minimally invasive total knee replacement (MIS-TKR) has been reported to have better early recovery than conventional TKR. Quadriceps-sparing (QS) TKR is the least invasive MIS procedure, but it is technically demanding with higher reported rates of complications and outliers. This study was designed to compare the early clinical and radiological outcomes of TKR performed by an experienced surgeon using the QS approach with or without navigational assistance (NA), or using a mini-medial parapatellar (MP) approach. In all, 100 patients completed a minimum two-year follow-up: 30 in the NA-QS group, 35 in the QS group, and 35 in the MP group. There were no significant differences in clinical outcome in terms of ability to perform a straight-leg raise at 24 hours (p = 0.700), knee score (p = 0.952), functional score (p = 0.229) and range of movement (p = 0.732) among the groups. The number of outliers for all three radiological parameters of mechanical axis, frontal femoral component alignment and frontal tibial component alignment was significantly lower in the NA-QS group than in the QS group (p = 0.008), but no outlier was found in the MP group. In conclusion, even after the surgeon completed a substantial number of cases before the commencement of this study, the supplementary intra-operative use of computer-assisted navigation with QS-TKR still gave inferior radiological results and longer operating time, with a similar outcome at two years when compared with a MP approach.

Mini-midvastus versus mini-medial parapatellar approach in total knee arthroplasty: a prospective, randomized study

INTRODUCTION

To date, no English literature has evaluated the short-term results of the mini-medial parapatellar approach compared with the mini-midvastus approach. This prospective, randomized study was performed to compare the short-term results of total knee arthroplasty using either a mini-midvastus or a mini-medial parapatellar approach.

PATIENTS AND METHODS

We reported the clinical and radiological results of 89 patients who had primary total knee arthroplasties with minimally invasive techniques using either a mini-midvastus or a mini-medial parapatellar approach. The mini-midvastus approach was used on 45 patients (group I) and a mini-medial parapatellar approach on 44 patients (group II). Skin incision length, tourniquet time, incidence of lateral retinacular release, total blood loss, straight leg raising time, visual analogy scale score, alignment of the knee, component position, and complication of each group were examined. Knee Society scores, range of motion were compared at 7 days, 6 weeks, 3 months, and 6 months postoperatively.

RESULTS

The mean tourniquet time was 68 min in group I, significantly longer than 56 min for group II. However, comparisons of postoperative knee scores and function scores between both approaches did not yield a significant difference in outcome. No significant difference was found with respect to total blood loss, visual analogy scale score, straight-leg-raising test, range of motion or radiographic findings.

CONCLUSION

Based on these results, we believe that the early results are similar between mini-midvastus and mini-medial parapatellar approach, ultimately the selection of the surgical approach will depend on the surgeon's experience and preference.

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.

What is the role of minimally invasive surgery in a fast track hip and knee replacement pathway?

INTRODUCTION

Minimally invasive hip and knee replacement surgery (MIS) continues to receive coverage in both the popular press and scientific literature. The cited benefits include a smaller scar, less soft tissue trauma, faster recovery, reduced hospital stay, decreased blood loss and reduced post-operative pain. These outcomes are highly desirable and consistent with the aims of fast track hip and knee pathways. This paper evaluates the literature and discusses whether performing MIS over conventional surgical techniques offers advantages in a fast track hip and knee pathway.

METHODS

An English language literature search was performed using the MEDLINE and PubMed databases. Case series, randomised controlled trials and systematic reviews were included in the review.

RESULTS

The reported improvements in recovery brought about by MIS must be considered multifactorial. In combination with improved clinical pathways, MIS can be associated with quicker recovery and shorter length of hospital stay.

CONCLUSIONS

There is insufficient evidence to indicate that surgical technique alone makes a significant difference to recovery or reduces soft tissue trauma. No consensus on whether to use MIS techniques in fast track hip and knee replacement pathways can therefore be drawn. This is especially important given that the complication rates of MIS in the low to medium volume surgeon appear unacceptably high compared with standard approaches. It is also too early to assess the long-term effects of MIS on implant survival.

Comparison of quadriceps-sparing minimally invasive and medial parapatellar total knee arthroplasty: a 2-year follow-up study

BACKGROUND/PURPOSE

Quadriceps-sparing minimally invasive total knee arthroplasty (TKA) has been proposed to limit surgical dissection without compromising surgical outcome. We conducted a prospective and randomized study to compare the outcomes of patients who underwent quadriceps-sparing TKA with the outcomes of those who underwent standard medial parapatellar TKA, after a 2-year follow-up period.

METHODS

Eighty primary TKA procedures that were to be performed in 60 osteoarthritis patients were randomly assigned to either a quadriceps-sparing (40 knees) or a standard medial parapatellar (40 knees) group. All surgeries were designed to set the prosthesis with a femoral component alignment of 7° valgus and a tibial component alignment that was perpendicular to the tibial shaft. Surgical time and tourniquet time were recorded. Outcome variables included knee function, as defined by a hospital for special surgery knee score; quadriceps muscle strength, which was measured by an isokinetic dynamometer; pain, as indicated on a visual analog scale; prosthetic position, which was measured on plain radiograph; and range of motion.

RESULTS

Patients who underwent the 38 quadriceps-sparing and 37 standard TKA procedures completed the 2-year follow-up period without any infection or revision. The mean surgical time and tourniquet time were significantly longer in the quadriceps-sparing group. The mean peak quadriceps muscle strength, hamstring muscle strength, normalized muscle balance (hamstring/quadriceps ratio), pain score, function score, and range of motion were comparable in both groups at 2 months and 2 years. In the quadriceps-sparing group, both the femoral and the tibial components were significantly more varus-deviated from the expected position.

CONCLUSIONS

Patients undergoing quadriceps-sparing and standard medial parapatellar TKA had comparable outcomes for quadriceps muscle strength, hamstring-quadriceps balance, and knee function; however, the quadriceps-sparing TKA was more time consuming surgically and resulted in a less accurate prosthesis position.

Early recovery after fast-track Oxford unicompartmental knee arthroplasty. 35 patients with minimal invasive surgery

BACKGROUND AND PURPOSE

After total knee arthroplasty with conventional surgical approach, more than half of the quadriceps extension strength is lost in the first postoperative month. Unicompartmental knee arthroplasty (UKA) operated with minimally invasive surgery (MIS) results in less operative trauma. We investigated changes in leg-extension power (LEP) in the first month after MIS Oxford UKA and its relation to pain, knee motion, functional performance, and knee function.

PATIENTS AND METHODS

In 35 consecutive Oxford UKA patients, LEP was measured 1 week before and 1 month after surgery together with knee motion, knee swelling, the 30-second chair-stand test, and Oxford knee score. Assessment of knee pain at rest and walking was done using a visual analog scale.

RESULTS

30 patients were discharged on the day after surgery, and 5 on the second day after surgery. LEP and functional performance reached the preoperative level after 1 month. Only slight postoperative knee swelling was observed with rapid restoration of knee flexion and function. A high level of pain during the first postoperative night and day fell considerably thereafter. None of the patients needed physiotherapy supervision in the first month after discharge.

INTERPRETATION

Fast-track MIS Oxford UKA with discharge on the day after surgery is safe and leads to early recovery of knee motion and strength even when no physiotherapy is used.

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).

The effectiveness of minimally invasive total knee arthroplasty to preserve quadriceps strength: a randomized controlled trial

We performed a single-center, randomized, double-blind study to compare muscle strength in patients who had undergone primary total knee arthroplasty (TKA), performed using either a minimally invasive or a conventional surgical technique. We evaluated 30 knees in healthy age-matched subjects, 22 knees after conventional TKA (conventional group), and 23 knees after minimally invasive surgery TKA (MIS group). The Hospital for Special Surgery (HSS) score, Oxford knee score (OKS), and isokinetic (60º/s) muscle strength were evaluated the day before surgery and 3, 6, and 12 months after surgery. HSS and OKS improved significantly over time during follow-up (p<0.001), but there was no significant difference between the groups (p>0.05). The extensor peak torque (EPT) and flexor peak torque (FPT) improved significantly over time (p<0.001) and EPT was greater in the MIS group than in the conventional group during the follow-up period (p<0.05). There was no difference in FPT and the hamstring-to-quadriceps ratio between the groups. Although MIS patients had a significant deficit in extensor strength following TKA, compared with healthy controls, this approach offers a significant improvement in extensor muscle strength over conventional surgery. These results suggest that the MIS approach results in better outcomes with regard to maintaining extensor strength than the conventional surgical approach.

Muscle damage during minimally invasive surgical total knee arthroplasty traditional versus optimized subvastus approach

Decreased muscle damage is reported as an advantage of minimally invasive surgical (MIS) approaches in total knee arthroplasty (TKA). The purpose of this study was to evaluate the anatomy of vastus medialis obliquus (VMO) tendon at its patellar insertion as well as to determine the amount and location of muscle damage comparing traditional subvastus approach and optimized subvastus approach. TKAs were performed in ten human cadavers (20 knees). In each specimen, one knee underwent the traditional subvastus approach and the contralateral knee the optimized subvastus approach. The risk of tearing and damaging the VMO muscle during the traditional subvastus approach is significantly higher (70% of the cases) compared to the optimized technique (30%). The amount of damage to the VMO muscle using the traditional subvastus approach was: 80% of the muscle's width in two cases, 60% in three cases, and 30% in two. The damage created by the optimized subvastus approach occurred along the edge of the tendon and the first fibers of the VMO muscle close to the muscle-tendon junction (less than 20% of muscle's width). Clinical studies are needed to determine the functional implications of these findings.

Soft tissue balance measurement in minimal incision surgery compared to conventional total knee arthroplasty

PURPOSES

Minimal incision surgery (MIS) total knee arthroplasty (TKA) is widely promoted as a possible improvement over conventional TKA, and accurate implantations have recently been reported using navigation systems. However, soft tissue balance during MIS-TKA remains challenging. Therefore, in this report, joint gap (component gap) and ligament balance (varus angle) were assessed during MIS-TKA using a tensor, which enables soft tissue balance assessment with a reduced patellofemoral joint and femoral component in place.

METHODS

Results were compared to those of conventional TKA. Posterior stabilized TKA were performed in 50 knees (25 knees: MIS-TKA using quadriceps-sparing approach; 25 knees: conventional TKA using medial parapatellar approach) with varus osteoarthritis. Component gap and varus angle were measured using the tensor with a reduced patellofemoral joint at 0, 10, 45, 90, and 135°.

RESULTS

Whereas the component gap in MIS-TKA was significantly larger through the entire arc of flexion compared with conventional TKA, the pattern of joint looseness showed no difference between the two procedures. The varus angle in MIS-TKA was significantly larger than that in conventional TKA at 0, 90, and 135° of knee flexion.

CONCLUSIONS

MIS-TKA may lead to ligament imbalance due to the difficulties induced by a limited working space. Understanding this pattern allows surgeons to be able to adjust the soft tissue balance more accurately and thereby expect a better post-operative outcome even in MIS-TKA.

Clinical and radiographic outcomes of minimally invasive total knee arthroplasty through a lateral approach

PURPOSE

With increasing confidence and surgical experience, minimally invasive surgery (MIS) in total knee arthroplasty (TKA) is now being applied to more complicated cases. The present study assessed the feasibility of MIS-TKA using a lateral approach for valgus knees.

METHODS

Subjects comprised 26 patients with valgus knees who underwent MIS-TKA using a lateral subvastus approach. Five cases required a 1-cm snip of vastus lateralis obliquus, to shift the patella medially without eversion. Clinical scores and radiographic parameters of lateral MIS-TKA were examined and compared with those of 26 medial MIS-TKAs matched for preoperative patient characteristics.

RESULTS

The lateral MIS-TKA group showed slightly longer operative time and larger skin incision than the medial MIS-TKA group. Nevertheless, myoglobin index and pain on a visual analog scale on postoperative day 7 were significantly lower in the lateral MIS-TKA group than in the medial MIS-TKA group. Postoperative improvement of clinical scores was quite comparable between lateral and medial MIS-TKA groups. Radiographic assessment revealed that tibiofemoral mechanical axis aligned within ±3° from ideal in 24 of 26 patients after lateral MIS-TKA. MIS technique-related complications occurred in only 1 patient presenting with subsidence of the tibial component, due to malpositioning of the tibial component.

CONCLUSION

From the perspectives of postoperative pain, clinical scores, radiographic accuracy, and postoperative complication rate, lateral MIS-TKA achieved comparable or superior results to medial MIS-TKA. This technique may offer a promising technical option that can be utilized for most patients with valgus knee deformity.

Early functional outcome after subvastus or parapatellar approach in knee arthroplasty is comparable

PURPOSE

In total knee arthroplasty, tissue-sparing techniques are considered more important, as functional gain could become more advantageous when early mobilization is commenced. The parapatellar approach is most often used, whereas the subvastus approach is a suitable alternative. Presently, it is unknown, according to true objective measurements, which of the two is most advantageous.

METHODS

In this prospective randomized double-blind, short-term trial measurements (KSS, WOMAC, PDI, VAS, ability to perform) were obtained at day 1, day 3, 1 week, 6 weeks, and 3 months.

RESULTS

The subvastus group (n=20) showed only significantly less extension lag direct postoperative (P=0.04) compared with the parapatellar group (n=20). Other scores were not significantly different. The Dynaport®knee test, an objective performance-based tool, could not demonstrate significant differences. A blunt anatomical dissection was carried out in both observational and histological to support findings. A dense innervation of the distal vastus medialis was found. This is at risk employing the subvastus approach. Both approaches harm the suprapatellar bursa. The vastus medialis sheath must be detached distally to open the knee joint. No true separate vastus medialis obliquus could be identified.

CONCLUSION

Comparable to literature, only mild advantage employing the subvastus approach was found, but only early postoperative and not objectively. As this approach is also not suitable in every case, we will continue to use the parapatellar approach.

Patella Eversion Reduces Early Knee Range of Motion and Muscle Torque Recovery after Total Knee Arthroplasty: Comparison between Minimally Invasive Total Knee Arthroplasty and Conventional Total Knee Arthroplasty

We hypothesized that patella eversion during total knee arthroplasty (TKA) reduces early return of active knee extension and flexion, quadriceps muscle strength, and postoperative pain. In 100 conventional TKA knees and 100 minimally invasive TKA (MIS TKA) knees, we compared knee range of motion (ROM), postoperative pain, and quadriceps muscle strength at 1 day, 4 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 12 weeks, 1 year, and 5 years after surgery. The differences of surgical approach between MIS TKA and conventional TKA of this study are length of skin incision with subcutaneal flap and patella eversion. In MIS TKA, skin incision is shorter than conventional TKA. Furthermore, patella is not everted in MIS TKA procedure. There were no significant differences in preoperative factors. Postoperative improvement of ROM, postoperative muscle strength recovery, and postoperative improvement of visual analog scale were faster in patients with MIS TKA when compared to that in patients with conventional TKA. On the other hand, no significant difference was observed in complication, 5-year clinical results of subjective knee function score, and the postoperative component angle and lower leg alignment. These results indicate that patella eversion may affect muscle strength recovery and postoperative pain.

Mini-subvastus versus a standard approach in total knee arthroplasty: a prospective, randomized, controlled study

This prospective randomized study compared the clinical and radiological results of primary total knee arthropasty (TKA) using a mini-subvastus approach (group I; n = 35) or a standard approach (group II; n = 33). A posterior-stabilized prosthesis was used in both groups by the same surgeon. Mean follow-up was 18 months (range 14 - 26 months). Patients in group I lost less blood and experienced less pain 1 day post-operatively. They achieved an active straight leg raise earlier and underwent less lateral retinacular releases. Functional outcome and the range of knee movements were significantly better in group I up to 9 months post-operatively, but there was no significant difference between the groups at 1 year post-operatively or at final follow-up. Reduced access and visibility in group I prolonged the operation time and resulted in five technical errors on radiographic evaluation. Based on these results, the authors currently only use the mini-subvastus approach for minimally invasive TKA in selected cases.

Accuracy of implant positioning for minimally invasive total knee arthroplasty in patients with severe varus deformity

Minimally invasive surgery (MIS) in total knee arthroplasty (TKA) reportedly yields decreased patient morbidity and a rapid return of function, but how much deformity can be accepted for MIS-TKA remains unclear. This study investigated 238 knees from 218 consecutive patients who underwent MIS-TKA. Patients were divided into groups with tibiofemoral mechanical axis (TFM) 195 degrees or greater and TFM less than 195 degrees, then clinical and radiographic results were compared. Similar improvements in knee score at 3 months postoperatively were obtained in the both groups, whereas radiographic accuracy of the coronal alignment in the TFM >or=195 degrees group was inferior to that in TFM <195 degrees group. Postoperative TFM was significantly worsened in patients with lateral bowing angle of the femoral shaft (LBFS) 4 degrees or greater, and 53% of patients in the TFM >or=195 degrees group displayed LBFS 4 degrees or greater, explaining the inferior radiographic accuracy in this group compared with the TFM <195 degrees group. These results indicate that use of MIS techniques decreases radiographic accuracy, particularly in patients with severe genu varum and increased LBFS.

Method for quantifying patient expectations and early recovery after total knee arthroplasty

Many components of a surgeon's total knee arthroplasty (TKA) treatment regimen affect the rate of recovery, such as patient selection, preoperative education, surgical technique, pain management, and postoperative rehabilitation. Therefore, accurate counseling requires that the surgeon quantifies patient expectations and early recovery of the treatment regimen with a method that minimizes interviewer bias. Preoperatively and 4 to 5 weeks after TKA, 285 patients (306 consecutive primary TKAs) responded to a survey consisting of customized questions, the Oxford score, the SF-12, and Knee Society scores on a handheld data acquisition device. The average response to each question on the 4- to 5-week postoperative survey defined patient expectations, and the change in a response between the 4- to 5-week postoperative and the preoperative survey determined whether the surgical intervention improved the patient. At 4 to 5 weeks postoperatively, 80% of patients walked without a cane, 54% drove a car, 88% thought the treated knee was functioning better than before surgery, 93.5% thought the treated knee was normal or nearly normal, and 98% thought the alignment of their limb was "just right." By 4 to 5 weeks, patients experienced less pain and showed significant improvements in 11 of 12 activities queried by the Oxford score, SF-12 physical score, Knee function score, Knee Society score, and knee extension. Flexion was significantly less at 4 to 5 weeks, and the SF-12 mental score was not significantly different. Average hospital stay was 2 nights, with 98% discharged home. Surgeons should consider a method that minimizes interviewer bias to quantify patient expectations and rate of recovery of their specific treatment regimen, and then use this information to counsel their patients to avoid disappointment after TKA.

Improving accuracy of total knee component cementation: description of a simple technique

Background

Total knee arthroplasty represents a common orthopedic surgical procedure. Achieving proper alignment of its components with the predrilled patellar and tibial peg holes prior to polymerization of the bone cement can be challenging.

Technique

After establishing the femoral, patellar and tibial bone cuts, the cancellous bone around the tibial keel, as well as the peg holes for the patella and femoral components are marked with methylene blue using a cotton swab stick. If bone cement is then placed onto the cut and marked bone edges, the methylene blue leaches through the bone cement and clearly outlines the tibial keel and predrilled femoral and patellar peg holes. This allows excellent visualization of the bone preparations for each component, ensuring safe and prompt positioning of TKA components while minimizing intraoperative difficulties with component alignment while the cement hardens.

Conclusion

The presented technical note helps to improve the accuracy and ease of insertion when the components of total knee arthroplasty are impacted to their final position.

Minimally invasive total knee arthroplasty: a systematic review

The concept of minimally invasive total knee arthroplasty surgery evolved to reduce quadriceps muscle strength loss and improve clinical outcome following total knee replacement. We performed a systematic review of the published literature on Minimally Invasive Total Knee Arthroplasty (MITKA) and analyzed the reported surgical outcomes. Twenty-eight studies published from January 2003 to June 2008 that met the inclusion criteria were evaluated using the modified Coleman Methodology Score (CMS). At a mean CMS of 60, most studies reporting on outcome of MITKA are of moderate scientific quality. Patients undergoing MITKA tend to have decreased postoperative pain, rapid recovery of quadriceps function, reduced blood loss, improved range of motion (mostly reported as a short-term gain) and shorter hospital stay compared with patients undergoing standard total knee arthroplasty. These benefits, however, need to be balanced against the incidence of increased tourniquet time and increased incidence of component malalignment in the MITKA group. So far, the evidence based knowledge regarding results of MITKA comes from prospective studies of moderate quality with short follow up periods. Multicenter studies with longer follow-ups are needed to justify the long-term advantages of MITKA over standard total knee arthroplasty.

Comparison of the early results of minimally invasive vs standard approaches to total knee arthroplasty: a prospective, randomized study

A prospective, randomized study was performed to compare early clinical and radiographic outcomes of total knee arthroplasty using either standard or minimally invasive surgical approaches. Fifty-nine patients were randomized into 3 groups: a standard median parapatellar incision (n = 19), a "mini mid-vastus" (n = 20), or a "quad sparing" group (n = 20). The procedures were performed by a single surgeon using similar perioperative protocols at 1 hospital. Postoperatively, the quad sparing group demonstrated some statistically significant (P < .05) improvement in week 2 and greater but not in weeks 1 and 6 compared to the other groups. No significant differences occurred regarding postoperative complications or radiographic alignment of the implants. In conclusion, our study demonstrated that the quad sparing group had some improved early results without compromising safety or efficacy.

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

A consecutive series of revision total knee arthroplasty (TKA) performed at 3 centers by 5 surgeons for a 3-year period was reviewed. Revisions performed for infection and rerevisions were excluded. Review of clinical and radiographic data determined incision type, sex, age, time to revision, and primary diagnosis at time of revision. Two-hundred thirty-seven first-time revision TKAs were performed, of which 44 (18.6%) had been a minimal incision surgery (MIS) primary TKA and 193 (81.4%) had been a standard primary TKA. Patients with MIS were younger (62.1 vs 66.2 years, P = .02). Most striking was the difference in time to revision, which was significantly shorter for the MIS group (14.8 vs 80 months, P < .001). Minimal incision surgery TKA accounted for a substantial percentage of revision TKA in recent years at these centers. The high prevalence of MIS failures occurring within 24 months is disturbing and warrants further investigation.

Accuracy of side-cutting implantation instruments for total knee arthroplasty

A new generation of implantation instruments were developed for quadriceps sparing surgical approaches during total knee arthroplasty (TKA). There is little information on the accuracy of the bone cuts performed with the side-cutting technique. A total of 100 patients were randomized to undergo computer-assisted TKA or non-navigated TKA using a mini-subvastus surgical approach and side-cutting implant instrumentation. The radiographic parameters, clinical outcomes and knee scores were evaluated 3 months postoperative. The mechanical axis of the limb was within 3 degrees varus/valgus in 76% of the patients who had navigated procedures versus 66% of patients who had conventional surgery. The tibial slope showed a rate of inaccuracy of 3 degrees or less for 78% of the patients in the navigated total knee arthroplasty group versus 66% of the patients in the conventional group. Clinical outcomes and knee scores were similar in both groups. The navigation technique could not compensate for shortcomings of the implantation instruments.

[Quadsparing approach in total knee arthroplasty]

OBJECTIVE

Approach to the knee joint for total knee arthroplasty (TKA) with gentle soft-tissue handling.

INDICATIONS

Primary TKA with range of motion>or=100 degrees, leg axis up to 10 degrees varus or valgus, body weight<100 kg.

CONTRAINDICATIONS

Contracted knees, leg axis>10 degrees varus or valgus, obesity, previous knee surgery except arthroscopic procedures, rheumatoid arthritis.

SURGICAL TECHNIQUE

Anterior midline incision. Soft-tissue preparation and capsule incision start at the upper tip of the patella and are continued distally along the medial patellar border ending at the tibial tuberosity. After opening of the joint, the patella is dislocated laterally without everting it. Exposure of the articular surface using a "mobile window". Preparation and insertion of the TKA components using special instruments. Wound closure in layers.

POSTOPERATIVE MANAGEMENT

Mobilization on crutches with full weight bearing starting on the day of surgery. Daily medical training therapy. Passive motion therapy continued twice a day. Low-dose heparin s.c. for 35 days after surgery.

RESULTS

In a prospective randomized clinical study, 50 patients with a quadsparing (QS) approach were observed up to 3 months after surgery. In three patients, the use of large femoral components required an extended approach. During the hospital stay knee flexion was significantly greater in patients with the QS approach than in patients with the standard procedure (midvastus approach). There were no differences in implant positioning, Knee Society Score and complication rate between both groups. Use of the QS approach prolonged the duration of surgery by 25 min.

Avaliação isocinética em pacientes submetidos à artroplastia total de joelho

OBJETIVOS: Tem-se afirmado que a via de acesso minimamente invasiva na artroplastia total de joelho (ATJ) por não agredir o músculo quadríceps femoral permite reabilitação mais precoce. A fim de verificar a influência da preservação do aparelho extensor no ato cirúrgico, avaliou-se a força da musculatura extensora e flexora do joelho em pacientes submetidos à ATJ por duas vias de acesso diferentes. MATERIAIS E MÉTODOS: Este estudo comparou, no período de janeiro de 2005 a julho de 2006, os valores de torque máximo e de trabalho total obtidos por dinamometria isocinética aos seis meses de pós-operatório. Foram avaliados 12 indivíduos submetidos a ATJ por via de acesso minimamente invasiva e 8 indivíduos submetidos a ATJ por via de acesso transquadricipital. RESULTADOS: A análise estatística dos valores de torque máximo e de trabalho total absolutos e corrigidos pelo peso corporal não demonstrou diferença entre os dois grupos. CONCLUSÃO: Não há diferença de força da musculatura extensora e flexora do joelho aos seis meses de cirurgia.

Analysis of factors affecting operating time, postoperative complications, and length of stay for total knee arthroplasty: nationwide web-based survey

BACKGROUND

This study aimed to clarify the impact of various factors on the operating time, postoperative complications, and length of stay (LOS) after total knee arthroplasty (TKA).

METHODS

We identified 3577 TKAs performed in 345 hospitals in Japan from November 2006 to March 2007. We examined the patient characteristics, surgical procedure details, hospital and surgeon volumes, and outcome variables (operating time, postoperative complications, LOS).

RESULTS

The average operating time was 127 +/- 47 min. The rate of postoperative complications was 9.8%. The average LOS was 35.1 +/- 15.9 days. In multivariate regression analyses, the average operating times were significantly shorter at hospitals with > or = 50 cases per year compared to hospitals with < 10 cases per year and for surgeons with > or =100 total cases compared to surgeons with < 100 total cases. A longer operating time was associated with revision surgery and use of computer navigation. Significant predictors of postoperative complications were age, body mass index, and cerebrovascular disease. Shorter LOS was associated with higher hospital volume and use of a clinical pathway, whereas age, cardiovascular disease, and revision surgery increased the length of stay.

CONCLUSIONS

Postoperative complications following TKA mainly depended on patient-based factors and were not significantly affected by the surgeon's experience.

Quadriceps muscle function in primary total knee arthroplasty

Patient expectations after primary total knee arthroplasty (TKA) continue to increase as the arthroplasty population becomes younger. Patients desire more than just pain relief, function, and the ability to return to higher level activities after TKA. Quadriceps muscle function and strength are critical determinants of this outcome. Many factors, including patient specific issues, surgical technique, and implant design, affect this function after TKA. This article will review our current understanding of quadriceps muscle function after TKA and the factors under the surgeon's control to achieve the best outcome.

Total knee replacement performed with either a mini-midvastus or a standard approach: a prospective randomised clinical and radiological trial

We report the clinical and radiological results of a two- to three-year prospective randomised study which was designed to compare a minimally-invasive technique with a standard technique in total knee replacement and was undertaken between January 2004 and May 2007. The mini-midvastus approach was used on 50 patients (group A) and a standard approach on 50 patients (group B). The mean follow-up in both groups was 23 months (24 to 35). The functional outcome was better in group A up to nine months after operation, as shown by statistically significant differences in the mean function score, mean total score and the mean Oxford knee score (all, p = 0.05). Patients in group A had statistically significant greater early flexion (p = 0.04) and reached their greatest mean knee flexion of 126.5 degrees (95 degrees to 135 degrees ) 21 days after operation. However, at final follow-up there was no significant difference in the mean maximum flexion between the groups (p = 0.08). Technical errors were identified in six patients from group A (12%) on radiological evaluation. Based on these results, the authors currently use minimally-invasive techniques in total knee replacement in selected cases only.

Current state and future of joint replacements in the hip and knee

Joint replacements of the hip and knee are among the most clinically successful operations. According to figures compiled by the American Academy of Orthopaedic Surgeons, the number of primary total hip replacements performed in the USA was 220,000 in 2003. This was 38% more than in 1996 and this number is expected to rise to 572,000 (plus another 97,000 revisions) by 2030. The number of primary total knee replacements performed in 2003 was approximately 418,000 and is expected to rise exponentially with the increasing numbers of baby boomers and the aging population. Current research focuses not only on extending implant longevity, but also on improving function to meet the increased demands of today's patients, who are likely to be younger and more active than their predecessors two decades ago. Potential advancements in arthroplasty surgery include new, more wear-resistant bearing surfaces, porous metals to enhance osseointegration and replace lost bone stock, a clearer understanding of the biological processes associated with periprosthetic osteolysis, minimally invasive surgery and computer assisted surgery. Long-term studies are needed to establish the efficacy of these new technologies.