Optimal patellar alignment with minimally invasive approaches in total knee arthroplasty after a minimum five year follow-up

Purpose

Patellofemoral syndrome is still a common complication after total knee arthroplasty (TKA). However, the effects of specific surgical approaches on patellar tracking and alignment remain incompletely understood. In this study, we compared patellar alignment in patients who underwent TKA via three different techniques.

Methods

A total of 96 patients who completed a minimum follow-up of five years were involved in three groups: 30 patients were treated with the traditional medial parapatellar approach (MPP group), 35 patients were treated with the mini-medial parapatellar approach (MMP group) and 31 were treated with a quadriceps-sparing approach (QS group). Radiographic data for patellar alignment and clinical results were compared.

Results

Patellar tilt and patellar displacement at the final follow-up evaluation differed significantly among the three groups [P?<?0.01, analysis of variance (ANOVA)]. The MMP and QS groups exhibited more proper patellar alignment than the MPP group. The clinical results did not differ significantly among the groups (P?>?0.05, ANOVA). In addition, there were no correlations between postoperative patellar alignment and clinical scores.

Conclusions

The results of this study indicate that TKA performed using minimally invasive approaches yields superior patellar alignment compared to the traditional MPP approach.

     

Navigation-assisted less invasive total knee arthroplasty compared with conventional total knee arthroplasty: a randomized prospective trial

The purpose of this study was to evaluate the hypothesis that a less invasive (LIS) surgical technique using a navigation system would promote rapid recovery and improve alignment compared with conventional technique in total knee arthroplasty (TKA). This study compared 49 navigation-assisted LIS TKAs with 53 conventionally performed TKAs using a medial parapatellar arthrotomy with patellar eversion. Navigation-assisted LIS TKA used a shorter skin incision, a midvastus approach without patella eversion, and a navigation system. Navigation-assisted LIS TKA had better pain scores, shorter times to achieve 90 degrees flexion and straight leg raise, and a smaller extension lag during the very early postoperative period. However, there were no differences between the groups 2 weeks postoperatively. There were no differences in mean prosthetic alignment between the 2 groups, but the navigation-assisted LIS group had fewer "outliers" than the conventionally performed TKA group.     

Quadriceps-sparing, minimal-incision total knee arthroplasty: a comparative study

Our study was conducted to compare radiographic alignments and functional outcomes with 2 approaches to minimal-incision total knee arthroplasty (TKA): the minimal-incision medial parapatellar (MP) approach and the quadriceps-sparing (QS) approach with side-cutting instruments. Sixty patients (80 knees) with primary osteoarthritis were randomly assigned to receive MP or QS TKA. Postoperative alignment of the femoral component was significantly less valgus, and postoperative alignment of the tibial component was significantly more varus with the QS approach than with the MP approach. One tibial outlier and 3 femoral outliers were observed with QS TKA. The overall postoperative hip-knee-ankle axis was more varus, and surgical time was longer with QS TKA. Short-term isokinetic peak muscle torque, postoperative pain, and functional outcomes did not differ between the approaches.     

A midvastus muscle-splitting approach for total knee arthroplasty

This study presents a modification of the medial parapatellar surgical approach for total knee arthroplasty. This approach separates the vastus mediatis muscle in the direction of its fibers beginning at the superior pole of the patella. One hundred eighteen consecutive total knee arthroplasty cases, performed by a single surgeon, were randomized prospectively to receive a medial parapatellar or midvastus muscle-splitting surgical approach. The frequency of lateral retinacular releases was recorded, patellar tilt and translation were measured, and quadriceps strength was tested. The midvastus muscle-splitting approach provided excellent exposure to all knees. Patellar stability and quadriceps strength were equivalent for the two approaches. It is concluded that the midvastus muscle-splitting approach is an efficacious alternative to the medial parapatellar approach for primary total knee arthroplasties.     

Osteonecrosis of bipartite patella following total knee arthroplasty without lateral release

We present a case of osteonecrosis of bipartite patella occurring after total knee arthroplasty using medial parapatellar approach without lateral retinacular release in osteoarthritic knee of a 66 year-old-male. The surgery was performed using traditional technique with medial parapatellar approach and patella was resurfaced. Patella was everted during surgery. There was no event during follow-up period after surgery. Range of motion of the knee was 135° without flexion contracture. Eight months after the surgery, patella was fragmented and resorbed on the radiographs which was consistent with osteonecrosis. The patient showed extension limitation of 30° with no pain. Patellar osteonecrosis has been rarely reported after total knee arthroplasty with lateral retinacular release. However, there was no report of patellar osteonecrosis after total knee arthroplasty without lateral retinacular release. Caution should be taken about patellar osteonecrosis in case of bipartite patella even though lateral retinaculum is preserved during total knee arthroplasty.     

Surgical accuracy with the mini-subvastus total knee arthroplasty a computer tomography scan analysis of postoperative implant alignment

A total of 50 total knee arthroplasty (TKA) patients, 25 traditional and 25 minimally invasive surgical (MIS), underwent computed tomography scans to determine if a loss of accuracy in implant alignment occurred when a surgeon switched from a traditional medial parapatellar arthrotomy to a mini-subvastus surgical technique. Surgical accuracy was determined by comparing the computed tomography measured implant alignment with the surgical alignment goals. There was no loss in accuracy in the implantation of the tibial component with the mini-subvastus technique. The mean variance for the tibial coronal alignment was 1.03 degrees for the traditional TKA and 1.00 degrees for the MIS TKA (P = .183). Similarly, there was no difference in the mean variance for the posterior tibial slope (P = .054). Femoral coronal alignment was less accurate with the MIS procedure, mean variance of 1.04 degrees and 1.71 degrees for the traditional and MIS TKA, respectively (P = .045). Instrumentation and surgical technique concerns that led to this loss in accuracy were determined.     

Minimally invasive total knee arthroplasty

Currently, minimally invasive total knee arthroplasty is defined as an incision length of < 14 cm. However, the length of the incision is not the primary influence on potential postoperative benefits to the patient and should not be the only characteristic of the minimally invasive approach for knee arthroplasty. Some other factors that should also be included in this definition are: 1. The amount of soft-tissue dissection (including muscle, ligament, and capsular damage). 2. Patellar retraction or eversion. 3. Tibiofemoral dislocation. Minimally invasive surgery should not be considered to be a cosmetic procedure but rather one that addresses patients' concerns with regard to postoperative pain and slow rehabilitation. Standard total knee arthroplasties provide pain relief, but returning to activities of daily living remains a challenge for some individuals, who may take several weeks to recover. Several studies have demonstrated long-term success (at more than ten years) of standard total knee arthroplasties. However, many patients remain unsatisfied with the results of the surgery. In a study of functional limitations of patients with a Knee Society score of > or = 90 points after total knee arthroplasty, only 35% of patients stated that they had no limitations. This finding was highlighted in a study by Dickstein et al., in which one-third of the elderly patients who underwent knee replacement were unhappy with the outcome at six and twelve months postoperatively. Although many surgeons utilize objective functional scoring systems to evaluate outcome, it is likely that the criteria for a successful result of total knee arthroplasty differ between the patient and the surgeon. This was evident in a report by Bullens et al., who concluded that surgeons are more satisfied with the results of total knee arthroplasty than are their patients. Trousdale et al. showed that, in addition to concerns about long-term functional outcome, patients' major concerns were postoperative pain and the time required for recovery. Patients undergoing total knee arthroplasty have specific functional goals, such as climbing stairs, squatting, kneeling, and returning to some level of low-impact sports after surgery. Our clinical investigations demonstrated that the minimally invasive surgical approach reduces hospital stays, decreases postoperative pain, and decreases rehabilitation needs as well as enables patients to return to normal function more quickly. It is important for surgeons to take an evolutionary, rather than a revolutionary, approach when performing minimally invasive total knee arthroplasty. The surgeon should downsize incisions progressively to prevent severe damage to the quadriceps mechanism. Extensive open exposure, prolonged patellar eversion, and dislocation of the tibiofemoral joint should evolve into a vastus medialis muscle split with patellar subluxation, retraction but not dislocation of the patella, and avoidance of gross dislocation of the tibiofemoral joint. Developing the techniques of minimally invasive total knee arthroplasty may be difficult and time-consuming, but patient benefits and satisfaction should outweigh the extra effort required. These changes require well-designed clinical studies to further document their effectiveness.     

A comparison of patellar vascularity between the medial parapatellar and subvastus approaches in total knee arthroplasty

A complication of total knee arthroplasty is patellar avascular necrosis. Surgical approaches for total knee arthroplasty include the medial parapatellar approach (MPa) and, less commonly, the subvastus approach (SVa). The argument that SVa retains better patellar vascularity than the MPa was investigated on 20 participants, (SVa, n = 10; MPa, n = 10) 18 months postoperatively. Outcomes were a radionuclide bone imaging technique, a new bone vascularity scale, and an anterior knee pain numerical assessment scale. Results indicated no significant difference between groups on imaging (P = .935), the components of the bone vascularity scale, or anterior knee pain (P > .999). The SVa appears to offer no benefit over the MPa in terms of patellar vascularity or anterior knee pain.     

Patellar blood flow during knee arthroplasty surgical exposure: Intraoperative monitoring by laser doppler flowmetry.

Patellofemoral complications following knee arthroplasty are a well-known problem. Patellar ischemia has been suspected to be causative for fracture, anterior knee pain, and patella component failure. The purpose of this study was to assess the influence of knee arthroplasty surgical dissection on patellar blood flow. Patellar blood flow was measured by means of intraosseous laser Doppler flowmetry (LDF) in 10 patients undergoing total knee arthroplasty by a standard medial parapatellar approach. The initial blood flow was 121.6 +/- 114.7 AU. The signal significantly decreased by 71% (p = 0.0051) when the knee was flexed and lost the pulsatile signal pattern in 80%. After arthrotomy, the signal was 100.1 +/- 120.3 AU in extension. The lowest signal was found in flexion and eversion of the patella (mean, 18 +/- 10.7 AU) and all signals lost pulsatility. As compared to the initial values, completion of the soft tissue dissection did not lead to a significant change of the blood flow signal (121.3 +/- 104.8; p = 0.6835). Flexion of the knee joint markedly reduced patellar perfusion. Standard medial parapatellar approach did not significantly change patellar blood flow. This study does not support the theory of postoperative patellar ischemia as a cause of anterior knee pain or patellofemoral problems.     

Minimally invasive total knee arthroplasty using the contralateral knee as a control group: a case-control study

The primary purpose of this study was to compare clinical and functional results of bilateral total knee arthroplasties in which a conventional total knee replacement was initially performed on one knee and a minimally invasive total knee replacement was later performed on the contralateral side. Operative factors, clinical and radiographic outcomes, and quadriceps muscle strength were evaluated in twenty-five patients (50 total knee arthroplasties). Twenty-one of the 25 patients preferred the minimally invasive approach. Knee society objective scores and range-of-motion were significantly greater in the minimally invasive group. Isokinetic testing demonstrated statistically improved quadriceps muscle strength in the minimally invasive technique group compared to the standard approach at both 12 weeks and one year postoperatively. Radiographic analysis did not reveal differences in alignment variables between the two approaches. The results of this study suggest that minimally invasive total knee arthroplasty offers superior short-term as well as possible long-term results.     

Progressive quadriceps incision during minimally invasive surgery for total knee arthroplasty: the effect on early postoperative ambulation

A prospective series of 114 consecutive minimally invasive surgeries for total knee arthroplasty was performed using the quadriceps-sparing approach at the beginning. Intraoperatively, when the knee was in 45 degrees to 60 degrees of flexion, lateral patella subluxation was evaluated. A progressive quadriceps tendon incision with a 1-cm increment was applied if the patella could not be completely slid. The mean follow-up time was 24 months. There were 3 groups according to the length of quadriceps incision: group A (17 knees) had no or 1-cm quadriceps incision; group B (60 knees) had 2-cm incision; and group C (37 knees) had 3-cm incision. The average operative time, blood loss, pain score, preoperative range of motion and postoperative range of motion at 2 weeks, 6 weeks, 12 weeks, and 3 months were not significantly different among groups. Patient ability for early ambulation (sitting, knee straightening, standing, and walking) was indifferent between groups A and B; however, this was significantly delayed in group C. In conclusion, minimally invasive surgery for total knee arthroplasty with 2-cm quadriceps incision or strict quadriceps-sparing approach provided no difference on early ambulation.     

Total knee arthroplasty in the valgus knee using a standard medial approach

Total knee arthroplasty in the valgus knee poses specific problems to the surgeon, such as the presence of ligament tightness on the lateral side. It has been claimed in the past that approaching the knee from the lateral side through a lateral parapatellar arthrotomy may therefore be a more logical and easier technique than the standard medial approach used conventionally. Many surgeons however do not wish to change their routine practice and therefore wish to stick to the classical medial approach they are used to, even in the presence of an underlying valgus deformity. In this paper, we therefore report the technical considerations that one should take into account when addressing the valgus knee through a standard medial approach. These include tightness of the lateral soft tissues, stretching of the medial collateral ligament, lateral bowing of the femoral shaft, and a tendency for lateralized patellar tracking. A review of 125 consecutive valgus knees treated at our institution through a standard medial approach while using these principles, has demonstrated an excellent operative outcome in the majority of cases.     

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.     

Surgical approaches in mini-incision total knee arthroplasty

Mini-incision total knee arthroplasty can be accomplished through versions of exposures used in standard total knee arthroplasty. Modifications of the medial parapatellar, subvastus, and midvastus approaches are presented, and potential advantages and disadvantages of each approach are reviewed. When making the transition to smaller incisions and arthrotomies, the medial parapatellar seems to be the most versatile. The ability to do a total knee arthroplasty through a mini incision, and ultimately the success of the procedure, will depend on appropriate patient selection.     

Association of increased knee flexion and patella clunk syndrome after mini-subvastus total knee arthroplasty

This study reviewed 747 consecutive posterior stabilized total knee arthroplasty (TKA) to explain the increased incidence of patella clunk syndrome that occurred when the surgeon switched from a medial parapatellar arthrotomy to a mini-subvastus (MIS) TKA technique. The incidence of patella clunk syndrome increased with increased postoperative knee flexion. Six weeks after surgery, knees that developed patella clunk had a mean flexion of 124 degrees vs 117 degrees for knees that did not develop this syndrome (P = .016). As the MIS approach resulted in increased knee flexion, this approach was indirectly associated with the increased incidence of patella clunk. Knee flexion at 6 weeks postoperatively was 117 degrees for the MIS knees vs 108 degrees for traditional medial parapatellar arthrotomy knees (P < .001). The effect of increased knee flexion achieved with the MIS approach, which resulted in an increase in patella clunk, was mitigated by using a new posterior stabilized femoral component designed to minimize soft tissue entrapment.     

Component alignment after minimally invasive total knee arthroplasty: results of the first 100 cases performed

It has been suggested that minimally invasive total knee arthroplasties increase the risk of component malalignment. Results during the period of initial learning curve on component malalignment are relatively unknown but should be addressed. This study reports the component alignment data of the first 100 minimally invasive total knee arthroplasties performed by a single surgeon from the very start of a community-based practice immediately after fellowship training. The results indicate that the initial learning curve produces results comparable to reported results of standard total knee arthroplasties.     

Minimally invasive Oxford medial unicompartmental knee arthroplasty

We present the peak outcome results of the Oxford medial unicompartmental arthroplasty through a minimally invasive surgical incision. This prospective study included 78 Oxford medial unicompartmental knee replacements in 68 patients. At the 2 year review the patients achieved a mean Oxford Knee Score of 38.3. This was not significantly different to the 2 year results of the phase 2 Oxford knee carried out using a standard parapatellar approach when patients achieved a mean OKS of 36.0. Four unicompartmental knee replacements required revision for unexplained pain, deep infection, aseptic loosening and bearing dislocation. Minimally invasive joint replacement is attractive to both patients and surgeons, but is technically demanding with complications inherent to limited access.     

Subvastus and medial parapatellar approaches in total knee arthroplasty

This retrospective study compared the outcome of two consecutive groups of patients having primary total knee arthroplasty. The arthroplasties were performed in the first group (169 arthroplasties in 143 patients) from 1988 to 1992 using a medial parapatellar approach, and in the second group (167 arthroplasties in 148 patients) from 1992 to 1996 using a subvastus approach. The patient outcomes were evaluated at 6 months, and were based on clinical and radiographic measures, occurrence of intraoperative lateral retinacular release, and incidence of postoperative patellar subluxation. There were no significant differences between the two groups for range of motion, Knee Society knee and function scores, and stair climbing ability. The patella tracked centrally in significantly more knees with the subvastus approach (139 of 167 knees, 83%) than with the parapatellar approach (107 of 169 knees, 63%). There were significantly fewer knees in the subvastus group requiring a lateral retinacular release (62 of 167 knees, 37%), compared with the parapatellar group (113 of 169 knees, 67%). The authors concluded that the subvastus approach led to improved patellar tracking and stability. Although the surgical and rehabilitative protocols were identical for both groups, the results may have been affected by changing circumstances during the 9-year period of the study.     

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.     

The effect of surgical approaches and tourniquet application on patellofemoral tracking in total knee arthroplasty

The purpose of this study was to assess the influences of surgical approaches and tourniquet application on the lateral retinacular tension (LRT). Single-setting bilateral total knee arthroplasty was performed in 10 patients, and the medial parapatellar and midvastus approaches were randomly performed on each knee using tourniquet application. The LRT was measured using the buckle transducer before and after each approach. Next, the tourniquet was deflated and the measurement was repeated. After the parapatellar approach, LRT was significantly decreased. Conversely, no significant change was seen after the midvastus approach with the tourniquet inflated. However, in the midvastus approach, LRT was significantly decreased after tourniquet deflation. We concluded that both the parapatellar and midvastus approaches influence patellar tracking and LRT.