Time dependent changes in patellar tracking with medial parapatellar and midvastus approaches

Midvastus Versus Medial Parapatellar Approach in Simultaneous Bilateral Total Knee Arthroplasty

BACKGROUND

The purpose of this study was to compare the postoperative outcomes over a period of 3 years in patients who underwent bilateral total knee arthroplasty (TKA) using midvastus (MV) versus medial parapatellar (MPP) approaches.

METHODS

In this retrospective study, 2 propensity-matched cohorts of patients who underwent simultaneous bilateral TKA via MV (n = 100) and MPP (n = 100) approaches from January 2017 to December 2018 were compared. Surgical parameters compared were surgery time and the incidence of lateral retinacular release (LRR). Clinical parameters including the visual analog score for pain, time for straight leg raise (SLR), range of motion, the Knee Society Score, and the Feller patellar score were assessed in the early postoperative and follow-up periods up to 3 years. Radiographs were evaluated for alignment, patellar tilt, and displacement.

RESULTS

LRR was performed on 17 knees (8.5%) in the MPP group and 4 knees (2%) in the MV group which was significant (P = .03). The time to SLR was significantly lower in the MV group. There was no statistically significant difference in the length of hospital stay between the groups. The visual analog score, range of motion, and Knee Society Score were better in the MV group within 1 month (P < .05), but no statistically significant differences were found later. Patellar scores, radiographic patellar tilt, and displacements were similar at all follow-up periods.

CONCLUSION

In our study, the MV approach had faster SLR, less LRR, and better pain and function scores in the first few weeks after TKA. However, its effect on different patient outcomes has not been sustained at 1 month and further follow-up points. We recommend that surgeons use the surgical approach with which they are most familiar.

How to optimize patellar tracking in knee arthroplasty?

Good patellar tracking is needed for functionally successful total knee arthroplasty (TKA), and depends on several factors. The aim of the present Instructional Lecture is to identify the main factors and how to control them so as to optimize patellar tracking: more or less "patella-friendly" prosthetic trochlea design, requiring precise assessment and choice of model; patellar component design; type of tibial implant; surgical approach and management of peripatellar structures, and any lateral release; distal and posterior femoral bone cuts, determining femorotibial alignment, femoral component rotation and patellar height; tibial implant rotation with respect to the anterior tibial tubercle; patellar cut characteristics in resurfacing. In case of instability or patellar maltracking despite correct implant positioning, there are 2 main surgical techniques: medial patellofemoral ligament reconstruction, and anterior tibial tubercle medialization. To obtain optimal patellar tracking, correction of other factors should be associated: trochlear component design, distal and posterior femoral bone cuts, tibial implant positioning, patellar component shape and positioning, etc.

Intraoperative patellar maltracking and postoperative radiographic patellar malalignment were more frequent in cases of complete medial collateral ligament release in cruciate-retaining total knee arthroplasty

BACKGROUND

Patellar maltracking after total knee arthroplasty (TKA) can lead to significant patellofemoral complications such as anterior knee pain, increased component wear, and a higher risk of component loosening, patellar fracture, and instability. This study was to investigate the preoperative and operative variables that significantly affect patellar tracking after cruciate-retaining TKA.

METHODS

We studied 142 knee joints in patients who had undergone TKA: the knees were dichotomized based on postoperative patellar tracking, which was evaluated on patellar skyline, axial-projection radiographs: group 1, normal patellar tracking (lateral tilt ≤ 10° and displacement ≤ 3 mm) and group 2, patellar maltracking (lateral tilt > 10° or displacement > 3 mm). The patients' demographic data and clinical and radiographic measurements obtained before and after surgery were compared between the two groups.

RESULTS

Preoperative lateral patellar displacement was greater (4.1 ± 2.6 mm vs. 6.0 ± 3.5 mm), as was the frequency of medial collateral ligament (MCL) release (3/67 vs. 24/75) in group 2 than in group 1 (p < 0.001 and p < 0.001, respectively). The distal femur was cut in a greater degree of valgus in group 1 than in group 2. (6.3 ± 0.8° vs. 6.0 ± 0.8°) (p = 0.034).

CONCLUSIONS

Complete release of the MCL during surgery was associated with patellar maltracking (logistic regression: p = 0.005, odds ratio = 20.592). Surgeons should attend to patellar tracking during surgery in medially tight knees.

LEVEL OF EVIDENCE

Retrospective comparative study, level III.

Does the type of surgical approach affect the clinical outcome of total knee arthroplasty?

Background

The aim of the study was to investigate the issue of medial midvastus (MMV) vs. medial parapatellar (MPP) approaches in total knee arthroplasty (TKA). It was hypothesized that the two surgical approaches would produce significantly different results with respect to patient-reported knee score outcome (hypothesis 1), short-term postoperative range of motion (ROM) (hypothesis 2), long-term postoperative ROM (hypothesis 3) and prosthesis survival (hypothesis 4).

Methods

A retrospective comparative study design was applied. Data sets were obtained from the state arthroplasty registry. The Western Ontario and McMaster Universities osteoarthritis index (WOMAC) data were analyzed from preoperative and 1 year postoperatively. The ROM data were analyzed for the time points preoperative, postoperative days 4 and 10 and 1 year.

Results

Available were 627 cases (407 MMV vs. 220 MPP) and 1 year postoperatively there were no significant differences between groups regarding the WOMAC scores (hypothesis 1). Early postoperatively on days 4 and 10 after TKA there were no differences between groups (p = 0.305 and p = 0.383, respectively, hypothesis 2). Likewise, ROM did not significantly differ between the groups 1 year after TKA (p = 0.338, hypothesis 3). The 5‑year prosthesis survival did not differ between the groups and showed 94.46% (95% confidence interval, CI 90.69–96.73%) in the MMV group and 94.33% (95% CI 89.96–96.83%) in the MPP group (p = 0.664, hypothesis 4).

Conclusion

Both surgical approaches produce equivalent clinical results in terms of early postoperative ROM, late postoperative ROM and 1‑year WOMAC. The same prosthesis survival rates can be expected.

The effect of tourniquets on patellofemoral joint congruity during total knee arthroplasty

BACKGROUND

Incongruity of the patellofemoral joint after total knee arthroplasty (TKA) causes anterior knee pain. Intraoperative congruity tests are necessary to avoid unnecessary lateral retinacular release, and the usage of tourniquets may influence these results. The purpose of this study was to examine the effect of tourniquets on patellofemoral joint congruity during TKA.

MATERIALS AND METHODS

Two hundreds and seventeen knees were examined after TKA. Skyline radiographs at 60° and 90° flexion were taken immediately after wound closure before and after tourniquet deflation to compare changes in patellar tilt angle.

RESULTS

In the patellar tilt angle at 60° flexion, lateral tilt was observed in 18 knees. Tourniquet deflation changed the patellar tilt angle by a mean -0.7° ± 1.2° (p = 0.030). Medial tilt was observed in 10 knees. Tourniquet deflation changed the patellar tilt angle by 0.9° ± 0.7° (p = 0.004). Tourniquet deflation improved the degree of lateral and medial patellar tilt. In the patellar tilt angle at 90° flexion, lateral tilt was observed in 118 knees. Tourniquet deflation changed the patellar tilt angle by a mean -1.1° ± 1.2° (p < 0.001). Medial tilt was observed in 71 knees. Tourniquet deflation changed the patellar tilt angle by 0.5° ± 1.0° (p < 0.001). Tourniquet deflation improved the degree of lateral and medial patellar tilt.

CONCLUSIONS

Tourniquet deflation improved patellofemoral congruity in a statistically significant way, but only to a small extent, indicating low clinical significance. Therefore, intraoperative congruity tests performed with tourniquets in place are reliable.

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.

Surgical approaches in total knee arthroplasty: a meta-analysis comparing the midvastus and subvastus to the medial peripatellar approach

Subvastus, midvastus and medial parapatellar approaches are the most popular approaches in total knee arthroplasty (TKA). However, the superior approach in TKA still remains controversial. We therefore conducted a meta-analysis to quantitatively compare the midvastus and subvastus approaches to the medial parapatellar approach in TKA. A total of 32 randomized controlled trials (RCTs) with 2451 TKAs in 2129 patients were included in this study. The meta-analysis suggested that, when compared with the medial parapatellar approach, the midvastus approach showed better outcomes in pain and knee range of motion at postoperative 1-2weeks but also was associated with longer operative time; the subvastus approach showed better outcomes in knee range of motion at postoperative 1week, straight leg raise and lateral retinacular release.

Minimally invasive midvastus versus standard parapatellar approach in total knee arthroplasty: a meta-analysis of randomized controlled trials

Objective

Minimally invasive midvastus approach (mini-midvastus) has been widely used in total knee arthroplasty (TKA). However, the clinical effects still remains controversial. This meta-analysis was based on randomized controlled trials (RCTs) aiming to quantitatively analyze the clinical efficacy of mini-midvastus versus standard parapatellar approach in TKA.

Methods

This meta-analysis was performed according to the PRISMA guidelines. A literature search for the eligible RCTs was carried out in the databases of PubMed, the Cochrane library, EMBASE and Web of Science. Two independent reviewers independently completed the study selection, data extraction, and the assessment of methodological quality. Meta-analysis was conducted by the RevMan 5.2 software.

Results

A total of 18 RCTs (937 patients with 1093 TKAs) published from 2007 to 2013 were included. The meta-analysis suggested that the mini-midvastus approach significantly improved knee range of motion (ROM) and decreased visual analog score (VAS) at postoperative 1–2 weeks (p<0.05), and there were no statistical differences in terms of knee society score (KSS) (6 weeks to 1 year), VAS (6 weeks to 6 months), ROM (6 weeks to 6 months), lateral retinacular release, blood loss, straight leg raise, hospital stay and postoperative complications between the mini-midvastus and standard parapatellar approach (p>0.05). However, the operative time was significantly longer when performing the mini-midvastus group than the parapartellar approach (p<0.05).

Conclusion

This meta-analysis found that compared with the standard parapatellar approach, the mini-midvastus approach had early advantages in the VAS and ROM, but had the disadvantage in the operative time.

Level of Evidence

Therapeutic study Level I.

Patellar tracking and anterior knee pain are similar after medial parapatellar and midvastus approaches in minimally invasive TKA

BACKGROUND

Since the medial parapatellar (MPP) approach in conventional TKA can cause patellar maltracking and anterior knee pain, some orthopaedic surgeons use the midvastus (MV) approach instead of the MPP approach to reduce patellar maltracking. Minimally invasive surgical (MIS) TKA has been developed to limit the damage to the surrounding muscle and reduce the necessity of patellar eversion during surgery. Thus, MIS TKA might be associated with proper patellar tracking and a low incidence of anterior knee pain. However, this presumption has not been confirmed.

QUESTIONS/PURPOSES

We asked whether the incidence of patellar maltracking and anterior knee pain differed with the MV and MPP in association with MIS TKA.

METHODS

We prospectively followed 59 patients (60 knees) treated with 60 primary cemented MIS TKAs from August 2009 to September 2010. We randomized the patients into two groups: 30 who had a limited MPP approach and 30 who had a mini-MV approach. We recorded the occurrence of anterior knee pain, patellar tilting, and subluxation. The minimum followup was 12 months (mean, 18.03 months; range, 12.00-25.08 months).

RESULTS

We found no differences in anterior knee pain (two of 30, 7% versus two of 30, 7%), mean patellar tilt (3.4º ± 2.9º versus 3.0 ± 2.3º), and mean patellar subluxation (1.5 ± 1.1 mm versus 1.1 ± 0.7 mm) between the limited MPP and mini-MV groups, respectively.

CONCLUSIONS

MIS TKA using either the MPP or MV approach has a low incidence of patellar maltracking and anterior knee pain.

Comparing the mid-vastus and medial parapatellar approaches in total knee arthroplasty: a meta-analysis of short term outcomes

PURPOSE

Proponents of a mid-vastus (MV) approach for primary total knee arthroplasties (TKA) stress its importance in preserving function of the extensor mechanism with earlier rehabilitation and decreased prevalence of lateral release. We conducted a meta-analysis of randomised and quasi-randomised controlled trials to compare functional outcomes of the standard medial parapatellar (PP) and mid-vastus (MV) approaches in primary knee arthroplasties.

METHODS

The study was conducted according to the guidelines described in the Cochrane Handbook for Systematic Reviews of Interventions. Methodological features were rated independently by two reviewers.

RESULTS

We included 18 studies involving 1040 patients with mean age of 69 (SD ± 2.7) for the MV and 68.8 (SD ± 2.8) for the PP group. Using a MV approach led to significant improvement in flexion (mean difference (MD) 8.88, 95% confidence interval (CI) 4.50 to 13.25, P<0.01) and visual analogue scale score (MD -1.72 95% CI -2.08 to -1.36, P<0.01) in the first week postoperatively and reduced the number of required lateral releases (risk difference -0.16 95% CI -0.30 to -0.01, P=0.03) with no increase in complication rates.

CONCLUSION

We conclude that the MV approach may provide an alternative to the standard PP approach with earlier rehabilitation and decreased lateral release rates in primary TKA and no increase in complication rates.

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.

Changes in patellar alignment after total knee arthroplasty

Although the results of total knee arthroplasty continue to improve, problems related to the patellofemoral joint remain significant. This study examined the factors affecting patellar alignment after total knee arthroplasty and subsequent changes in 56 knees during a postoperative period of 5.3 years. None of the knees examined displayed any clinical complications of the patellofemoral joint; no revision surgeries were necessary, with acceptable patellar alignment on average. The patellar resection angle had a strong influence on patellar alignment. Thinning of the patellar remnant on the medial side can increase postoperative lateral tilt, which leads to a need for lateral retinacular release. Although the changes in patellar alignment were minimal, the tendency that postoperative varus alignment resulted in patellar lateral tilt was observed. As postoperative femorotibial misalignment can lead to patellofemoral problems after total knee arthroplasty, surgeons need to pay scrupulous attention to femorotibial alignment and proper patellar preparation to decrease patellofemoral complications.

The effect of patellar thickness changes on patellar tilt in total knee arthroplasty

We hypothesized that changes in patellar thickness following patellar resurfacing affect patellar tilt in total knee arthroplasty (TKA) patients. The study enrolled 272 TKAs and categorized them into four groups according to change in patellar thickness: (A) thinner by 1 mm or more, (B) equal or thinner by less than 1 mm, (C) thicker by 1 mm or less, and (D) thicker by more than 1 mm. Patellar tilt angle was measured postoperatively using Merchant radiography. There were no significant differences in postoperative patellar tilt among groups A, B, and C (n.s). However, the postoperative patellar tilting angle of group D was significantly higher than that of all other groups (P < 0.05). Postoperative patellar tilt increased when the postoperative patella was >1 mm thicker than the preoperative patella.