Need For Lateral Retinacular Release Research Articles

Preoperative Radiological Parameters Predicting the Need for Lateral Retinacular Release in Total Knee Arthroplasty

BackgroundProper patellar tracking is essential for well-functioning total knee arthroplasty (TKA). Besides implanting components in the correct position and rotation, balancing parapatellar soft tissues is also important in aiding normal patellar tracking. Patellar maltracking during TKA can be improved by lateral retinacular release (LRR). MethodsWe studied the incidence of LRR in consecutive primary TKA with nonresurfaced patella and posterior-stabilized implant design. We analyzed data from 250 consecutive primary TKAs (212 patients) from January 2016 to May 2016. We evaluated the preoperative radiological parameters like patellar tilt, patellar shift, patellar morphology, Insall-Salvati ratio, femoro-tibial angle, distal femoral valgus angle, and proximal tibia varus angle which predict the need for LRR during TKA. We used multivariate regression analysis to find the association of individual radiological parameters and the LRR. ResultsThe need for LRR is significantly associated with preoperative radiological parameters like patellar shift and patellar tilt (P < .001). Compared to the nonreleased group, the adjusted odds of LRR were greater for morphological parameters like Wiberg type 3 patella (odds ratio [OR] 17.45, 95% confidence interval [CI] 7.21-42.20), lateral facet thinning (OR 4.38, 95% CI 2.37-8.07), lateral patellofemoral arthritis (OR 14.36, 95% CI 6.82-30.23), and coronal valgus deformity (OR 4.95, 95% CI 1.60-10.68). ConclusionPreoperative assessment of these radiological parameters in the axial view implies a high chance of tight lateral retinacular structures. This helps in identifying patients who have a higher likelihood for patellar maltracking during TKA. Appropriate LRR helps to provide better patellar tracking post TKA.

Soft Tissue Releases in Total Knee Arthroplasty for Valgus Deformities

BackgroundPrimary total knee arthroplasty (TKA) for valgus knee deformities can be challenging. Soft tissue releases are often necessary to achieve a well-balanced knee. We reviewed the frequency of soft tissue releases including lateral retinacular release (LRR) as it pertains to preoperative limb alignment. Postoperatively, we evaluated limb alignment, knee range of motion, and complications. MethodsFrom 2010 to 2016, 214 primary TKAs with valgus deformity were performed by a single surgeon. One hundred eighty-one patients had an average follow-up of 24 months. For these patients, clinical data including preoperative and postoperative range of motion, complications, and revision rates were collected. Soft tissue releases, preoperative and postoperative limb axis deviation, and level of prosthetic constraint were recorded in all patients regardless of length of follow-up. ResultsThere were 33 knees (15%) that required 1 release, 69 knees (32%) required 2 releases, 81 knees (38%) required 3 releases, and 31 knees (14%) that required 4 or more releases. The average preoperative mechanical axis was 9.4°, and the average postoperative mechanical axis was 0.13°. There were 85 knees (40%) that required an LRR. Increased severity of preoperative deformity correlated with the need for more soft tissue release, but did not correlate with the need for LRR. No knees were revised for instability. No patella complications resulted from LRR. ConclusionSelective soft tissue release for primary valgus TKA was effective without increasing prosthetic constraint. Severe deformities required more soft tissue releases. LRR can be frequently used with minimal complications.

The mid-vastus approach: a compromise between the medial parapatellar approach and the minimally invasive approach in total knee arthroplasty

Objectives The study was conducted to evaluate midvastus approach in total knee arthroplasty. Background The medial parapatellar approach, originally described by Von Langenbeck in 1879, remained as the work horse in total knee replacement surgery. The major problems in this technique are reduction of patellar blood flow, extensor mechanism imbalance, and the need for lateral retinacular release in some cases. The vastus medialis approach appeared as an alternative to the traditional medial parapatellar incision, with which to minimize the risks of extensor mechanism imbalance. When using this approach, no special instruments, as in the case of minimally invasive surgery, is needed. The same benefits could be achieved, such as proper visualization during surgery and shorter operative time. Patients and methods This is a prospective study of 29 primary knee arthroplasties performed using the midvastus approach without patellar eversion in Suez Canal University Hospital between May 2008 and June 2010. Mobile-bearing cruciate-substituting total knee prosthesis was used in all cases. Results Operative data showed no increase in the operative time with no significant increase in the blood loss. No lateral retinacular release was needed. The bone defects can be treated easily through this approach. No serious complications were encountered in patients, except in one case in which infected prosthesis was observed. Conclusion The approach is universal and can be recommended for all patients (except for revision cases and in cases of severe deformities). The results are better in this approach compared with the standard approach, with earlier return to start straight leg raising, faster pain relief, and shorter hospital stay.

Effect of Total Knee Prosthesis Design on Patellar Tracking and Need for Lateral Retinacular Release

Intraoperative lateral retinacular release (LRR) during primary total knee arthroplasty (TKA) is discouraged, except when LRR is necessary to centralize patellofemoral tracking. This study compares the LRR rates in four designs of total knee implants and correlates how changes in prosthesis design affect LRR rates. 2881 primary TKAs performed by one surgeon using a single surgical technique were reviewed. After controlling for all variables, LRR rates dropped from 71.6% to 19.5% to 9.7% to 2.7% with each design change (P<.0001). Differences in varus/valgus alignment and male/female proportions were compared in each group and the differences did not correlate with LRR rates. This study concludes that changes and improvements in knee implant designs play a significant role in decreasing lateral retinacular release rates in TKA.

Paper 105: 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 during a postoperative period of 5.3 years. Fifty-five knees in 39 patients were retrospectively evaluated by radiography for postoperative patellar alignment. This study included four men and 35 women with a mean follow-up time of 5.3 years (range: 2.5 to 8.4). All procedures utilized identical surgical technique; through a midline skin incision and medial parapatellar arthrotomy, the patella was fully everted. We adjusted the rotation of the femoral component until it was parallel to the surgical epicondylar axis. Using the posterior femoral condyles as references, we inserted the femoral components with 3° to 5° of external rotation to the posterior condylar axis according to preoperative CT scans. Tibial components were set using the medial third of the tibial tuberosity as a reference. All patellae were resurfaced with three-peg offset-dome all-polyethylene patellar component. Patellar alignment was assessed by measuring the lateral tilt and lateral displacement in skyline views taken with the knees at approximately 60° of flexion. Patellar alignment was evaluated one month after surgery, and at final follow-up. Changes in patellar lateral tilt angle and lateral displacement in the postoperative period were calculated using data obtained one month after surgery and at final follow-up. We did not observe severe malalignment of the femorotibial joint, patellar bone fracture, prosthesis failure, or any other clinical complications after TKA in any cases. The mean patellar lateral tilt angle was -0.7° (range: −13.7 to 7.0°) one month after surgery and −0.4° (range: −11.4 to 11.6°) at final follow-up. The mean patellar lateral displacement was 1.1mm (−2.7 to 6.6mm) one month after surgery and 0.9mm (−3.7 to 5.8mm) at final follow-up. We observed a negative correlation between the patellar resection angle and lateral tilt one month after surgery (p<0.0001) and between the patellar resection angle and patellar lateral displacement one month after surgery (p=0.0003). Lateral retinacular release was required for thirteen knees. In these cases, the resection angle was significantly smaller than that seen in knees without lateral retinacular release (p=0.0012). These results demonstrate that a smaller resection angle correlated with an increased frequency of lateral retinacular release. The change in patellar lateral tilt angle after 5.3 years was 0.3° (range: −7.2 to 7.0°), while the change in patellar lateral displacement was −0.3 mm (range: −5.2 to 3.7 mm). These changes did not significantly correlate with patellar alignment at any time point, resection angle, resection thickness, lateral retinacular release, or clinical results. The postoperative femorotibial alignment, however, exhibited a statistically significant correlation with the changes in lateral tilt angle (p=0.020). A more varus postoperative alignment correlated with increased lateral tilt of the patella in the postoperative period. We observed a satisfactory patellar alignment after a postoperative period of 5.3 years. The patellar resection angle had a significant effect on postoperative patellar alignment. Our findings suggest that leaving a thicker patellar remnant on the medial side can decrease postoperative lateral tilt and the resulting need for lateral retinacular release. Postoperative changes in patellar alignment were very small; none of the knees demonstrated complications of the patellofemoral joints. In this study, we observed the tendency that a postoperative varus alignment leads to patellar lateral tilt. Surgeons should pay scrupulous attention to femorotibial alignment during total knee arthroplasty to decrease patellofemoral complications and femorotibial problems.

Combining different rotational alignment axes with navigation may reduce the need for lateral retinacular release in total knee arthroplasty

The aim of the study was to compare femoropatellar alignment and the incidence of lateral retinacular release (LRR) in total knee arthroplasty (TKA) in which the rotational alignment of the femoral component was determined using a combination of different rotational alignment axes and navigation or a single reference axis in the standard procedure. We assessed 66 patients undergoing TKA in whom the rotation of the femoral component was determined on the posterior condylar axis in standard procedures (group A) and 65 patients in whom it was determined by combining the posterior condylar axis, anteroposterior axis and epicondylar axis in navigated procedures (group B). The mean age was 68 and 69 years in groups A and B, respectively. Patellar tracking was assessed after deflation of the tourniquet and LRR performed in the presence of maltracking. Visual analogue scale (VAS), Knee Society Score (KSS), Lonner patellar score and patellar tilt were recorded. LRR was carried out in 18 cases (27 %) in group A and in four (6 %) in group B (p = 0.003). The KSS and VAS were improved significantly compared to the preoperative status, but with no significant differences between the two groups. The patellar score showed a greater improvement in the navigated compared to the standard group at the four week follow-up. Patella tilt improved significantly in both groups. The complication rate was similar in the two groups. Combining different rotational alignment axes with navigation significantly reduces patellar maltracking and the need for LRR compared to the standard procedure in which the posterior condylar axis is used as single anatomical reference.

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 5.3years. 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.

Should the ‘no thumb technique’ be the golden standard for evaluating patellar tracking in total knee arthroplasty?

We checked intraoperative patellar tracking with both ‘towel clip technique’ and the ‘no thumb technique’ on 97 patients (167 knees) who underwent primary total knee arthroplasty to decide whether to do or not to do lateral retinacular release. Patellar tracking was assessed under pneumatic tourniquet with the no thumb technique first and re-evaluated with the towel clip technique. The tracking was graded as total contact, good contact, lateral contact and subluxation. The knees graded as total or good contact with the no thumb technique were classified into group A; those graded lateral contact or subluxation by the no thumb technique but total or good contact by the towel clip technique were classified into group B; and those graded lateral contact or subluxation by both techniques were classified into group C; in which lateral releases were performed. One hundred three, 53 and 11 knees were classified into groups A, B and C respectively. Of the 167 knees, 64 (38.3%) showed poor tracking (lateral contact or subluxation) with the no thumb technique alone. Re-evaluation of these knees with the towel clip technique significantly reduced the number with poor tracking to 11 (6.6%) knees requiring lateral retinacular release ( p < 0.05). The patients were followed up for 1 year without any patella-related complications occurring. Assessment of the patellar tracking using only the no thumb technique may overestimate the need for lateral retinacular release. The use of the no thumb technique as a screening test, and re-evaluation with the towel clip technique may reduce unnecessary lateral retinacular release.

Early results of total knee arthroplasty performed through the midvastus approach

The aim of this study was to evaluate the early results of total knee arthroplasty (TKA) performed through the midvastus approach. This retrospective study included 48 knees of 42 patients (29 females, 13 males; mean age 69 years; range 54 to 82 years) who underwent TKA for grade 4 knee osteoarthritis. All TKA operations were performed by the same orthopedic surgeon through the midvastus approach. Preoperatively, 40 patients (95.2%) had primary osteoarthritis, and two patients (4.8%) had rheumatoid arthritis. In all cases, a posterior stabilized cemented prosthesis with a fixed insert was used. Patellar resurfacing was performed in seven knees (14.6%). All the knees were rated according to the Knee Society knee and function scores before surgery and at the final follow-up. Postoperative radiographic evaluations were performed on anteroposterior and lateral radiographs according to the Knee Society TKA Roentgenographic Evaluation and Scoring System. The mean follow-up period was 26 months (range 12 to 49 months). The mean knee score significantly improved from 49.0+/-9.3 preoperatively to 87.5+/-9.9 postoperatively (p=0.000). The corresponding increase in the knee function score was from 48.8+/-9.9 to 79.6+/-14.0 (p=0.000). The mean increases in the knee and function scores were 38.5 and 30.8 points, respectively. The knee and function scores were excellent or good in 46 knees (95.8%) and 42 knees (87.5%), respectively. The mean knee flexion significantly increased by 28.6 degrees , from 84.3+/-14.7 degrees preoperatively to 112.9+/-11.9 degrees postoperatively (p=0.000). Among patients with bilateral osteoarthritis, the knee function scores were significantly higher in patients who had undergone bilateral versus unilateral TKA (90.0+/-11.5 and 78.8+/-10.8, respectively; p=0.007). None of the patients had patellar tracking abnormality intraoperatively; thus, there was no need for lateral retinacular release. Postoperative clinical and radiographic assessments showed no signs of instability or loosing. Clinical and radiographic loosening of the patella and osteolysis were not observed in patients who had undergone patellar replacement. No changes were observed in the tracking and position of the protheses. Neurovascular injury did not occur. One patient who developed early infection of the knee that required a two-stage revision was assessed as failure. In our study, lateral retinacular release was not needed due to achievement of proper patellar tracking in TKA operations with the midvastus approach, and satisfactory clinical and radiographic results were obtained.

The Effect of Stuffing the Patellofemoral Compartment on the Outcome of Total Knee Arthroplasty

The effect of so-called stuffing of the patellofemoral compartment at the time of total knee arthroplasty (that is, increasing the anterior patellar displacement, the anteroposterior femoral size, or the combined anteroposterior patellofemoral size) has not been well studied. The purpose of the present study was to evaluate the effect of stuffing the patellofemoral compartment on the outcome of primary total knee arthroplasty. A retrospective review of 1100 primary total knee arthroplasties that had been performed in 1997 and 1998 was conducted. Eight hundred and thirty arthroplasties (75.5%) met the diagnostic and minimum two-year follow-up criteria for inclusion in this report. Radiographic measurements were made to determine preoperative and postoperative anterior patellar displacement, anteroposterior femoral size, combined anteroposterior patellofemoral size, anterior femoral offset, and posterior femoral offset. Regression analysis was performed to determine the effects of changes in these variables on the range of motion, the Knee Society Knee Score, the Knee Society Function Score, the Knee Society Pain Score, and the rate of lateral retinacular release. Preoperative to postoperative changes in anterior patellar displacement, anteroposterior femoral size, combined anteroposterior patellofemoral size, anterior femoral offset, and posterior femoral offset had no clinically meaningful effect on the range of motion of the knee or on any of the Knee Society scores. Increases in anterior patellar displacement were associated with a lower probability of the need for a lateral retinacular release. Increases in measured anteroposterior femoral size were associated with a higher probability of the need for lateral release. Even when combined, however, these relationships explained only 10.1% of the observed variance in the need for lateral retinacular release. Moreover, analyses indicated that patient gender, large as opposed to medium patellar size, and absolute femoral component size influenced the likelihood of lateral release more than did anterior patellar displacement and measured anteroposterior femoral size. Our findings do not support the widely held belief that stuffing of the patellofemoral joint results in adverse outcomes after total knee arthroplasty. Furthermore, the need for lateral release appears to be multifactorial and likely involves a more complex set of factors. Thus, without evidence of other identifiable causes of failure, we do not recommend revision for the treatment of pain of an overstuffed knee joint.

The Effect of Stuffing the Patellofemoral Compartment on the Outcome of Total Knee Arthroplasty

Background: The effect of so-called stuffing of the patellofemoral compartment at the time of total knee arthroplasty (that is, increasing the anterior patellar displacement, the anteroposterior femoral size, or the combined anteroposterior patellofemoral size) has not been well studied. The purpose of the present study was to evaluate the effect of stuffing the patellofemoral compartment on the outcome of primary total knee arthroplasty. Methods: A retrospective review of 1100 primary total knee arthroplasties that had been performed in 1997 and 1998 was conducted. Eight hundred and thirty arthroplasties (75.5%) met the diagnostic and minimum two-year follow-up criteria for inclusion in this report. Radiographic measurements were made to determine preoperative and postoperative anterior patellar displacement, anteroposterior femoral size, combined anteroposterior patellofemoral size, anterior femoral offset, and posterior femoral offset. Regression analysis was performed to determine the effects of changes in these variables on the range of motion, the Knee Society Knee Score, the Knee Society Function Score, the Knee Society Pain Score, and the rate of lateral retinacular release. Results: Preoperative to postoperative changes in anterior patellar displacement, anteroposterior femoral size, combined anteroposterior patellofemoral size, anterior femoral offset, and posterior femoral offset had no clinically meaningful effect on the range of motion of the knee or on any of the Knee Society scores. Increases in anterior patellar displacement were associated with a lower probability of the need for a lateral retinacular release. Increases in measured anteroposterior femoral size were associated with a higher probability of the need for lateral release. Even when combined, however, these relationships explained only 10.1% of the observed variance in the need for lateral retinacular release. Moreover, analyses indicated that patient gender, large as opposed to medium patellar size, and absolute femoral component size influenced the likelihood of lateral release more than did anterior patellar displacement and measured anteroposterior femoral size. Conclusions: Our findings do not support the widely held belief that stuffing of the patellofemoral joint results in adverse outcomes after total knee arthroplasty. Furthermore, the need for lateral release appears to be multifactorial and likely involves a more complex set of factors. Thus, without evidence of other identifiable causes of failure, we do not recommend revision for the treatment of pain of an overstuffed knee joint. Level of Evidence: Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.

Comparison of the Vastus-Splitting and Median Parapatellar Approaches for Primary Total Knee Arthroplasty: A Prospective, Randomized Study

A vastus-splitting approach for total knee arthroplasty has been advocated to preserve function of the extensor mechanism and to decrease the prevalence of lateral release. Critics have claimed that there is greater blood loss and compromised exposure in large patients who are managed with this approach. The purpose of the present study was to compare vastus-splitting and median parapatellar approaches for primary total knee arthroplasty. Forty-two consecutive patients (fifty-one knees) undergoing primary total knee arthroplasty were randomized to treatment with a median parapatellar or vastus-splitting approach. The interval of the vastus muscle split was marked with radiopaque vascular clips. Surgical data, functional parameters, and preoperative and postoperative electromyograms were assessed. Early (six-month) and intermediateterm (five-year) follow-up showed no differences in functional parameters, tourniquet time, or the frequency of patellar resurfacing. Significantly more lateral releases (p < 0.01) and greater blood loss (p = 0.03) occurred in the median parapatellar group. Nine (43%) of twenty-one knees in the vastus-splitting group had abnormal electromyographic findings at six months postoperatively, whereas all patients in the median parapatellar group had normal findings. Seven knees with abnormal electromyographic findings at six months had normal findings when restudied at five years; in each of these knees, the vastus split had been developed bluntly. The other two knees with abnormal findings at six months had had sharp dissection for the muscle split. Both of these knees had chronic changes, one with changes indicative of reinnervation and the other with ongoing denervation, but neither demonstrated functional compromise. The vastus-splitting approach offers a viable alternative to the median parapatellar approach for primary total knee arthroplasty that reduces the need for lateral retinacular release without impairment of quadriceps function. Electromyographic abnormalities in the quadriceps muscle have no functional consequence and most likely represent reversible neurapraxic injury that may be avoided by blunt dissection in the vastus medialis muscle.

Total Knee Arthroplasty in Valgus Knees Using a Lateral Approach

We investigated the results of the use of the lateral approach in knees with fixed valgus deformity undergoing total knee arthroplasty (TKA) and compared them with the more commonly used midvastus approach at a minimum 2 years of follow-up. Fifty-five valgus knees in 48 patients underwent TKA via a lateral approach. Twenty-five knees in 24 patients formed our control (midvastus) group. Clinical and radiographic Knee Society scores were measured preoperatively, at 2 to 3 months postoperatively, and at latest follow-up. Only 3 (5.5%) knees of the study group required a constrained prosthesis. In postoperative scores, a significant (P = .003) difference in favor of the midvastus group was present for the early functional score only. In 7 (29.2%) of the control group, a lateral retinacular release was required. The lateral approach allows for the use of minimally constrained implants and provides excellent results and optimal patellar tracking, without the need for lateral retinacular release, in the valgus knee undergoing TKA.

A Clinical Comparison of Patellar Tracking Using the Transepicondylar Axis and the Posterior Condylar Axis

Two different methods for femoral component rotation in total knee arthroplasty (TKA) were compared with regard to the need for lateral retinacular release and 3-year follow-up knee society scores of both patellofemoral function and 3-year radiographs of the patella. The posterior condylar axis was used in 1322 consecutive primary TKAs, and the transepicondylar axis (TEA) was used in 1059 consecutive primary TKA. A significant decrease in lateral retinacular release was observed from 56.9% (752 knees) using the posterior condylar axis down to 12.3% (130 knees) using the TEA. No significant differences in knee society scores were observed between the 2 groups with regard to stair climbing, pain, patella radiographs, or range of motion. Routine use of the TEA is recommended for determining femoral component rotation in TKA.

COMPARISON OF THE VASTUS-SPLITTING AND MEDIAN PARAPATELLAR APPROACHES FOR PRIMARY TOTAL KNEE ARTHROPLASTY

Background: A vastus-splitting approach for total knee arthroplasty has been advocated to preserve function of the extensor mechanism and to decrease the prevalence of lateral release. Critics have claimed that there is greater blood loss and compromised exposure in large patients who are managed with this approach. The purpose of the present study was to compare vastus-splitting and median parapatellar approaches for primary total knee arthroplasty. Methods: Forty-two consecutive patients (fifty-one knees) undergoing primary total knee arthroplasty were randomized to treatment with a median parapatellar or vastus-splitting approach. The interval of the vastus muscle split was marked with radiopaque vascular clips. Surgical data, functional parameters, and preoperative and postoperative electromyograms were assessed. Results: Early (six-month) and intermediate-term (five-year) follow-up showed no differences in functional parameters, tourniquet time, or the frequency of patellar resurfacing. Significantly more lateral releases (p < 0.01) and greater blood loss (p = 0.03) occurred in the median parapatellar group. Nine (43%) of twenty-one knees in the vastus-splitting group had abnormal electromyographic findings at six months postoperatively, whereas all patients in the median parapatellar group had normal findings. Seven knees with abnormal electromyographic findings at six months had normal findings when restudied at five years; in each of these knees, the vastus split had been developed bluntly. The other two knees with abnormal findings at six months had had sharp dissection for the muscle split. Both of these knees had chronic changes, one with changes indicative of reinnervation and the other with ongoing denervation, but neither demonstrated functional compromise. Conclusions: The vastus-splitting approach offers a viable alternative to the median parapatellar approach for primary total knee arthroplasty that reduces the need for lateral retinacular release without impairment of quadriceps function. Electromyographic abnormalities in the quadriceps muscle have no functional consequence and most likely represent reversible neurapraxic injury that may be avoided by blunt dissection in the vastus medialis muscle. Level of Evidence: Therapeutic Level I. See Instructions to Authors for a complete description of levels of evidence.

Comparison of the Vastus-Splitting and Median Parapatellar Approaches for Primary Total Knee Arthroplasty: A Prospective, Randomized Study

A vastus-splitting approach for total knee arthroplasty has been advocated to preserve function of the extensor mechanism and to decrease the prevalence of lateral release. Critics have claimed that there is greater blood loss and compromised exposure in large patients who are managed with this approach. The purpose of the present study was to compare vastus-splitting and median parapatellar approaches for primary total knee arthroplasty. Forty-two consecutive patients (fifty-one knees) undergoing primary total knee arthroplasty were randomized to treatment with a median parapatellar or vastus-splitting approach. The interval of the vastus muscle split was marked with radiopaque vascular clips. Surgical data, functional parameters, and preoperative and postoperative electromyograms were assessed. Early (six-month) and intermediate-term (five-year) follow-up showed no differences in functional parameters, tourniquet time, or the frequency of patellar resurfacing. Significantly more lateral releases (p < 0.01) and greater blood loss (p = 0.03) occurred in the median parapatellar group. Nine (43%) of twenty-one knees in the vastus-splitting group had abnormal electromyographic findings at six months postoperatively, whereas all patients in the median parapatellar group had normal findings. Seven knees with abnormal electromyographic findings at six months had normal findings when restudied at five years; in each of these knees, the vastus split had been developed bluntly. The other two knees with abnormal findings at six months had had sharp dissection for the muscle split. Both of these knees had chronic changes, one with changes indicative of reinnervation and the other with ongoing denervation, but neither demonstrated functional compromise. The vastus-splitting approach offers a viable alternative to the median parapatellar approach for primary total knee arthroplasty that reduces the need for lateral retinacular release without impairment of quadriceps function. Electromyographic abnormalities in the quadriceps muscle have no functional consequence and most likely represent reversible neurapraxic injury that may be avoided by blunt dissection in the vastus medialis muscle.

Subvastus Approach for Total Knee Arthroplasty

The indications for the subvastus approach in total knee arthroplasty are the same for a medial parapatellar approach in the appropriately selected patient. The subvastus approach does not violate the quadriceps mechanism, reduces the need for lateral retinacular release, preserves the patella blood supply, and, with our modifications, can be used in most cases.