Evaluation of patellar retinacular tension during total knee arthroplasty. Special emphasis on lateral retinacular release

Sensor-Assisted Total Knee Arthroplasty: A Narrative Review

Wireless intraoperative load sensors have been used to improve the quality of soft-tissue balancing during total knee arthroplasty(TKA). Recent studies using the sensors have demonstrated reductions in gap imbalance, as well as early improvement of patient-reported clinical outcomes and low rates of arthrofibrosis. However, well-designed prospective studies are needed to determine whether the application of the sensor technology for TKA will have clinical benefits and improve the survival of prosthesis. Knowledge of the load-sensing technology (advantages and disadvantages, potential pitfalls, and future prediction) is crucial to apply this new TKA technique successfully. Herein, we conduct a narrative review of previous studies on this technique.

Lateral patellar retinacular release: changes over the last ten years

Lateral retinacular release is a useful resource in knee surgery that can be used for disorders of the extensor mechanism. For many years, it was indiscriminately used in the treatment of the various patellofemoral joint alterations, with conflicting functional results. This study aimed to analyze the changes that have occurred in the indications and clinical effectiveness of lateral retinacular release by reviewing the relevant literature of the past ten years, comparing it to the classic literature on the subject. It was found that less extensive releases decompress the lateral patellar facet, helping with pain control, while decreasing the risks of medial subluxation. Nowadays, there is clear evidence for its indication in the lateral patellar hypercompression syndrome associated with anterior knee pain, as long as there is no related instability; furthermore, it will normally play an adjuvant role in extensor mechanism alignment surgeries for cases of recurrent patellar instability. The initial results for symptomatic patellofemoral osteoarthritis are promising when lateral release is combined with cartilage debridement; in total knee replacement, it is more commonly used for the correction of valgus deformity in order to improve the components' congruency. Finally, distinguishing the different patellofemoral joint pathologies is seen as crucial in order to indicate this procedure. Further randomized control trials that compare surgical techniques with long-term results are still needed.

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.

Increased turn/amplitude parameters following subvastus approach in total knee arthroplasty

PURPOSE

To compare the improvement of the vastus medialis component of the quadriceps muscle electrophysiologically after the subvastus and medial parapatellar approaches in total knee arthroplasty (TKA).

METHODS

A total 26 patients that underwent primary unilateral in TKA were included into the study. TKAs were carried out via subvastus approach in 15 patients, while 11 patients were operated via medial parapatellar approach. The electrophysiological evaluations were carried out blindly with regard to the type of the surgical approach before the operation and at 6th week post-operatively. Non-surgical side was also evaluated as a control. Assessments were patellar tendon reflex analysis, motor unit potential analysis and interference pattern analysis (IPA) including turn-amplitude analysis and IPA during maximum contraction.

RESULTS

When they were compared to the pre-operative values, "the total mean amplitude" and "the mean turn/sec" parameters were significantly increased in group of subvastus approach (p = 0.017 and p = 0.009, respectively) at the post-operative 6th week. We would not be able to find any difference regarding the other electrophysiological parameters. There was also no significant difference between groups.

CONCLUSION

If there was no significant difference in all the electrophysiological parameters, the increase in turn-amplitude analysis in the group of subvastus approach would be considered as an indicator of a faster functional improvement of knee extensor mechanism in these cases.

Decreased ratios of lateral to medial patellofemoral forces and pressures after lateral retinacular release and gender knees in total knee arthroplasty

PURPOSE

To demonstrate that lateral to medial patellofemoral force and pressure ratios could be a surrogate marker of retinacular tension and patellar tracking.

METHODS

The patellofemoral forces of six knees from three fresh-frozen half-body female cadavers were evaluated with a capacitive sensor under simulated operative conditions in six staged clinical scenarios: native knees, knee arthroplasty without patellar resurfacing, resurfaced knee and patella, resurfaced knee and patella with lateral release, gender-specific knee arthroplasty with patella resurfacing, and gender-specific knee arthroplasty with lateral release. Maximum force and peak pressure were simultaneously recorded during three to four ranges of motion. Average values were compared between lateral and medial patellofemoral compartments as an objective measure of patellar tracking for the different settings.

RESULTS

Significant differences in lateral and medial force and pressure differentials were seen in most scenarios despite clinically normal patellar tracking. Lateral to medial ratios of maximum force and peak pressure significantly increased after TKA (2.9, 2.1) and after patella resurfacing (2.8, 2.6) compared to the native knee (1.6, 1.8). Addition of a lateral release in resurfaced knees decreased the ratio of lateral to medial patellofemoral forces and pressures as did gender knee arthroplasty (1.5 and 1.1, 2 and 1.3, respectively). Pressure and force values most closely resembled the native knee in the resurfaced knee/resurfaced patella with lateral release and in the gender knee arthroplasty scenarios.

CONCLUSIONS

Use of lateral to medial patellofemoral force ratios as a surrogate objective marker for patellar tracking was validated in this study by decreasing ratios observed after lateral release in TKA and with gender-specific implants.

Tibial tubercle osteotomy or quadriceps snip in two-stage revision for prosthetic knee infection? A randomized prospective study

BACKGROUND

Although 7% to 38% of revision total knee arthroplasties (RTKAs) are attributable to prosthetic knee infections, controversy exists regarding the best surgical approach while reducing the risk of extensor mechanism complications and the reinfection rate.

QUESTIONS/PURPOSES

We compared The Knee Society Score(©) (KSS), incidences of complications, maximum knee flexion, residual extension lag, and reinfection rate in patients with prosthetic knee infections treated with two-stage RTKAs using either the tibial tubercle osteotomy (TTO) or the quadriceps snip (QS) for exposure at the time of reimplantation.

METHODS

We prospectively followed 81 patients with chronic prosthetic knee infections treated between 1997 and 2004. Patients were randomized to receive a TTO or QS for exposure at the time of reimplantation. All patients had the same rehabilitation protocol. The minimum followup was 8 years (mean, 12 years; range, 8-15 years).

RESULTS

Patients in the TTO group had a higher mean KSS than the QS group (88 versus 70, respectively). Mean maximum knee flexion was greater in the TTO group (113° versus 94°); with a lower incidence of extension lag (45% versus 13%). We observed no differences in reinfection rate between groups.

CONCLUSIONS

We found the TTO combined with an early rehabilitation protocol associated with superior KSS did not impair extensor mechanism function or increase the reinfection rate. We believe a two-stage RTKA with TTO is a reasonable approach for treating prosthetic knee infections.

LEVEL OF EVIDENCE

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

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

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

The analysis of risk factors in no thumb test in total knee arthroplasty

Background

We would like to analyze the risk factors of no thumb test among knee alignment tests during total knee arthroplasty surgery.

Methods

The 156 cases of total knee arthroplasty by an operator from October 2009 to April 2010 were analyzed according to preoperative indicators including body weight, height, degree of varus deformity, and patella subluxation and surgical indicators such as pre-osteotomy patella thickness, degree of patella degeneration, no thumb test which was evaluated after medial prepatella incision and before bone resection (1st test), no thumb test which was evaluated with corrective valgus stress (2nd test, J test), and the kind of prosthesis. We comparatively analyzed indicators affecting no thumb test (3rd test).

Results

There was no relation between age, sex, and body weight and no thumb test (3rd test). Patellar sulcus angle (p = 0.795), patellar congruence angle (p = 0.276) and preoperative mechanical axis showed no relationship. The 1st no thumb test (p = 0.007) and 2nd test (p = 0.002) showed significant relation with the 3rd no thumb test. Among surgical indicators, pre-osteotomy patella thickness (p = 0.275) and degeneration of patella (p = 0.320) were not relevant but post-osteotomy patellar thickness (p = 0.002) was relevant to no thumb test (3rd test). According to prosthesis, there was no significance with Nexgen (p = 0.575). However, there was significant correlation between Scorpio (p = 0.011), Vanguard (p = 0.049) and no thumb test (3rd test). Especially, Scorpio had a tendency to dislocate the patella, but Vanguard to stabilize the patella.

Conclusions

No thumb test (3rd test) is correlated positively with 1st test, 2nd test, and post-osteotomy patella thickness. Therefore, the more patella osteotomy and the prosthesis with high affinity to patellofemoral alignment would be required for correct patella alignment.

Subvastus and medial parapatellar approaches in TKA: comparison of functional results

The purpose of this study was to compare the clinical results of total knee arthroplasty (TKA) in the early and late postoperative period using subvastus and medial parapatellar approach. A prospective randomized controlled study was conducted in a group of 169 patients (180 TKAs) with 2-year follow-up. Patients were divided into a study group (97 TKAs) with a subvastus approach and a control group (83 TKAs) with a parapatellar approach. Assessment of the results of both operating approaches was based on functional, clinical Knee Society Score, and pain (visual analog scale). Patients in the subvastus group achieved full active extension, better range of motion, and better Knee Society Score results at 12 days, 6 weeks, and 12 weeks earlier than patients in the medial parapatellar group. They also had less pain at 12 days. No statistically significant differences existed between assessed end points in both groups at 24- and 52-weeks, and 24-months postoperatively. The subvastus approach has given patients better early clinical results; however, at longer follow-up, both groups had similar outcomes. The potential benefits of the subvastus approach are: protection of the extensor mechanism from damage, less risk of damaging the blood supply to the patella, earlier clinical recovery, and less pain in the early postoperative period. The subvastus approach is an alternative to the standard medial parapatellar approach in TKA. It can be used with equally good results, especially taking into consideration positive clinical aspects in the early postoperative period.

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.

The effect of femoral component rotation on the extensor retinaculum of the knee

Malrotation of the femoral component may cause patellofemoral complications after total knee replacement (TKR). We hypothesized that femoral component malrotation would cause excessive lengthening of the retinacula. Retinacular length changes were measured by threading fine sutures along them and attaching these to the patella and to displacement transducers. The knee post-TKR was flexed-extended while the quadriceps were tensed, then the measurements repeated after rotating the femoral component 5 degrees internally and then 5 degrees externally. Internal rotation shortened the medial patellofemoral ligament (MPFL) significantly from 100 degrees to 0 degrees extension. External rotation lengthened the MPFL significantly from 90 degrees to 0 degrees extension. The transverse fibers of the lateral retinaculum showed no significant differences. The MPFL attaches directly from bone to bone, so it was lengthened directly by movement of the trochlea and patella, whereas the deep transverse fibers of the lateral retinaculum attach to the mobile iliotibial tract, so they were not lengthened directly.

Biomechanical consequences of patellar component medialization in total knee arthroplasty

The optimal amount of patellar component medialization in knee arthroplasty is unknown. We measured the impact, on patellofemoral kinematics and contact force distribution, of 0.0-, 2.5-, and 5.0-mm patellar component medialization in 7 cadaveric specimens implanted with knee arthroplasty components. The knees were flexed dynamically in a weight-bearing rig. Medialization led to lateral shift of the patellar bone, slight medial shift of the patellar component in the femoral groove, lateral tilt of the patella, reduced patellofemoral contact force in later flexion, and lateral shift of the center of pressure in early flexion. Effects on shift and tilt were proportional to the amount of medialization. As a result of this investigation, we recommend medializing the patellar component slightly-on the order of 2.5 mm.

Sub-vastus approach is more effective than a medial parapatellar approach in primary total knee arthroplasty: a randomized controlled trial

In a prospective single-centre longitudinal randomized controlled trial 116 patients were allocated to the sub-vastus approach, and 115 to the medial parapatellar approach. At one week follow-up, compared to baseline, range of motion, Knee Society (KS) global, KS knee, and KS pain scores were significantly better in the sub-vastus group. At the one year follow-up, WOMAC global and pain scores, SF36 physical function and role-physical scores, and EuroQol utility and pain score were significantly better in the sub-vastus group. The ease of exposure in the sub-vastus approach was significantly worse. There was no significant difference in length of stay or analgesia intake. The sub-vastus approach to total knee arthroplasty was more effective than a medial parapatellar approach at both one week and one year post-operatively, but surgeons reported a less easy exposure in the sub-vastus group.

Correcting lateral patellar tilt at the time of total knee arthroplasty can result in overuse of lateral release

Ninety-nine patients undergoing primary total knee arthroplasty were prospectively evaluated for pre-resurfacing and post-resurfacing patellar thickness and medial patellar liftoff at 30 degrees of flexion without manual pressure on the patella. Regardless of medial patellar liftoff, no lateral releases were performed. Tibiofemoral angles, patellar tilt, and patellar congruence angles were measured preoperatively and postoperatively. There were no patellar subluxations, dislocations, or complications related to the patellofemoral joint. Patellar tilt improved from 7.9 degrees preoperatively to 3.8 degrees postoperatively. Patients with 10 mm or more of intraoperative liftoff improved from 9.9 degrees tilt preoperatively to 6.6 degrees postoperatively. Patients with no intraoperative liftoff had a change from 6.3 degrees to 2.9 degrees . Although the 2 groups were statistically different, the amount of change in alignment was not different between the groups. Patients with medial patellar liftoff at the time of arthroplasty do not appear to require lateral release to yield acceptable postoperative patellofemoral alignment.

Sub-vastus approach versus the medial parapatellar approach in primary total knee: a randomised controlled trial [ISRCTN44544446]

BACKGROUND

Thirty thousand knee replacements are performed annually in the UK. There is uncertainty as to the best surgical approach to the knee joint for knee arthroplasty. We planned a randomised controlled trial to compare a standard medial parapatellar arthrotomy with sub-vastus arthrotomy for patients undergoing primary total knee arthroplasty in terms of short and long term knee function.

METHODS

Patients undergoing primary total knee arthroplasty at the local NHS Trust are to be recruited into the study. Patients are to be randomised into either the sub-vastus or medial parapatellar approach to knee arthroplasty. The primary outcome measures will be the American Knee Society and WOMAC Scores. The secondary outcome measures will be patient based measures of EuroQol and SF-36. All outcomes will be measured pre-operatively, 1, 6, 12 and 52 weeks post-operatively. We will also review pain intensity using a pain and analgesia diary. Ease of surgical exposure and complications will also be analysed.

DISCUSSION

Evidence is lacking concerning the best surgical approach to the knee joint for patients undergoing primary total knee replacement. This pragmatic randomised trial tests the hypothesis that the sub-vastus approach is significantly superior to the standard medial parapatellar approach in terms of short and long term knee function.

Indications for lateral retinacular release in total knee replacement

The rule of no thumb test was compared with the towel clip test in determining the need for lateral retinacular release in 200 consecutive primary total knee replacements. The towel clip test was positive in 13 knees (6.5%) and the rule of no thumb test was positive in 78 knees (39%). Using a positive towel clip test as the indication for lateral retinacular release, there was no radiographic evidence of patellar tilt, subluxation, or dislocation in any knee at 6 months postoperatively. Therefore, the rule of no thumb test falsely predicted the need for lateral release in 65 knees (32.5%). The authors advocate the towel clip test to determine the need for lateral retinacular release.

Anterior knee pain with a posterior-stabilized mobile-bearing knee prosthesis: the effect of femoral component design

Femoropatellar problems have been reported with some designs of posterior-stabilized knee prostheses with fixed bearings; we report similar findings with a posterior-stabilized mobile-bearing prosthesis. A review of 184 patients (193 knees) who underwent placement of a Rotaglide (Corin, Cirencester, UK) posterior-stabilized prosthesis with patellar resurfacing showed that only 33 knees (17%) had complete absence of femoropatellar complaints after at least 1 year of follow-up evaluation. Femoropatellar grinding was noted in the other 160 knees; 65 were asymptomatic, 78 were mildly symptomatic, and 17 were severely symptomatic. Two patients refused secondary treatment; 15 underwent arthroscopic debridement. The only abnormal finding was intra-articular fibrosis surrounding the patellar implant. After arthroscopic debridement of the fibrosis, all patients reported immediate relief of their symptoms followed by recurrence within 6 to 9 months. Inappropriate trochlear design of the femoral implant appears to be the main determinant of femoropatellar problems in these patients. Encroachment on the trochlea by a broad intercondylar box with a sharp anterior edge appears detrimental to function irrespective of the presence or absence of bearing mobility.

Alternate surgical approaches in mobile-bearing total knee arthroplasty

Surgical approaches in nonconstrained mobile-bearing total knee arthroplasty (TKA) should provide the best access for specific deformity correction. Alternatives to the standard medial approach include the medial midvastus and subvastus approaches, and the direct lateral approach, with or without tibial tubercle osteotomy or proximal "rectus snip." The direct lateral approach is a recommended alternative for fixed valgus knees, especially if there is lateral patellar subluxation and significant rotational deformity. The subvastus and midvastus medial approaches preserve quadriceps integrity and patella stability, and are recommended for severely unstable knees in nonobese, non-fixed valgus, and medial unicompartmental knee replacements.

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.