Less anterior knee pain with a routine lateral release in total knee arthroplasty without patellar resurfacing: a prospective, randomized study

Bilateral simultaneous total knee arthroplasty with and without patellar resurfacing. A prospective single surgeon series with a minimum follow-up of 7 years

BACKGROUND

Total knee arthroplasty (TKA) is the most effective treatment for end-stage adult knee osteoarthritis, but it has been reported that patient satisfaction may vary. A malfunction of the patellofemoral joint may produce anterior knee pain (AKP) for several reasons. While some surgeons systematically resurface the patella despite the risk of potential complications such as fracture, loosening, or wear of the patella, others prefer to preserve it to reduce AKP and revision rates. This study aimed to evaluate whether patellar resurfacing had better clinical and functional outcomes, complications, and revision rates in patients undergoing simultaneous bilateral total knee arthroplasty.

METHODS

We conducted a prospective cohort study, including patients who underwent bilateral simultaneous TKA in which the patella was replaced in one knee and preserved in the other, with a minimum follow-up of 7 years. We assessed clinical and functional outcomes with the Knee Society Score (KSS) and Visual Analogue Scale (VAS); complications and revision rates were also registered.

RESULTS

The final series consisted of 43 patients with 86 knee arthroplasties. After a mean of 7.6 years of follow-up, no significant differences were found regarding KSS (clinical: 82.8 ± 7.4 versus 83.2 ± 3.4, p = 0.92; functional 89.1 ± 8.2: versus 90.4 ± 6.8; p = 0.99), VAS (2.0 ± 0.9 versus 1.8 ± 1.0; p = 0.84), complications (10.5% versus 8.1%; p = 0.57), or revision rates (2.3% versus 2.3%; p = 0.99) when comparing patellar resurfacing versus retention.

CONCLUSION

In the context of total knee arthroplasty, patellar replacement did not demonstrate statistically significant differences concerning patellar retention in clinical nor functional outcomes, AKP, complications, or revision rates after a minimum of 7 years of follow-up.

Meta-analysis of factors influencing anterior knee pain after total knee arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) is a mature procedure recommended for correcting knee osteoarthritis deformity, relieving pain, and restoring normal biomechanics. Although TKA is a successful and cost-effective procedure, patient dissatisfaction is as high as 50%. Knee pain after TKA is a significant cause of patient dissatisfaction; the most common location for residual pain is the anterior region. Between 4% and 40% of patients have anterior knee pain (AKP).

AIM

To investigate the effect of various TKA procedures on postoperative AKP.

METHODS

We searched PubMed, EMBASE, and Cochrane from January 2000 to September 2022. Randomized controlled trials with one intervention in the experimental group and no corresponding intervention (or other interventions) in the control group were collected. Two researchers independently read the title and abstract of the studies, preliminarily screened the articles, and read the full text in detail according to the selection criteria. Conflicts were resolved by consultation with a third researcher. And relevant data from the included studies were extracted and analyzed using Review Manager 5.4 software.

RESULTS

There were 25 randomized controlled trials; 13 were comparative studies with or without patellar resurfacing. The meta-analysis showed no significant difference between the experimental and control groups (P = 0.61). Six studies were comparative studies of circumpatellar denervation vs non-denervation, divided into three subgroups for meta-analysis. The two-subgroup meta-analysis showed no significant difference between the experimental and the control groups (P = 0.31, P = 0.50). One subgroup meta-analysis showed a significant difference between the experimental and control groups (P = 0.001). Two studies compared fixed-bearing TKA and mobile-bearing TKA; the results meta-analysis showed no significant difference between the experimental and control groups (P = 0.630). Two studies compared lateral retinacular release vs non-release; the meta-analysis showed a significant difference between the experimental and control groups (P = 0.002); two other studies compared other factors.

CONCLUSION

Patellar resurfacing, mobile-bearing TKA, and fixed-bearing TKA do not reduce the incidence of AKP. Lateral retinacular release can reduce AKP; however, whether circumpatellar denervation can reduce AKP is controversial.

Lateral Retinacular Release During Medial Unicompartmental Knee Arthroplasty in the Presence of Patello-Femoral Joint Arthritis Relieves Patello-Femoral Joint Pressure and Improves Associated Symptoms

BACKGROUND

This study evaluated the effects of concomitant lateral patellar retinacular release (LPRR) during medial unicompartmental knee arthroplasty (UKA).

METHODS

We retrospectively analyzed 100 patients who had patello-femoral joint (PFJ) arthritis who underwent medial UKA with (n = 50) and without (n = 50) LPRR who had ≥2 years follow-up. Radiological parameters associated with lateral retinacular tightness, including patellar tilt angle (PTA), lateral patello-femoral angle (LPFA), and congruence angle, were measured. Functional evaluation was performed using the Knee Society Pain Score, Knee Society Function Score (KSFS), Kujala Score, and the Western Ontario McMaster Universities Osteoarthritis Index score. Intraoperative patello-femoral pressure evaluation was performed on 10 knees to evaluate the pressure changes before and after LPRR. Mann-Whitney U-tests were used for statistical analyses.

RESULTS

Demographic data did not differ between the LPRR(+) and LPRR(-) groups. A decrease in PTA and an increase in LPFA were observed in the LPRR(+) group compared to those in the LPRR(-) group (PTA; -0.54 versus -1.74, P = .002, LPFA; 0.51 versus 2.01, P = .010). The LPRR(+) group showed significantly better KSFS and Kujala scores than the LPRR(-) group (KSFS: 90 versus 80, P = .017; Kujala score: 86 versus 79, P = .009). Intraoperative patello-femoral pressure analysis showed a 22.6% reduction in the PFJ contact pressure and an 18.7% reduction in PFJ peak pressure after LPRR. (P = .0015, P < .0001, respectively) CONCLUSION: A LPRR during UKA may be a simple and useful adjunct procedure to relieve PFJ symptoms with concomitant PFJOA.

Systematic lateral retinacular release does not reduce anterior knee pain after total knee arthroplasty with patellar resurfacing

PURPOSE

The aim of this study was to assess the effect of systematic lateral retinacular release (LRR) on anterior knee pain (AKP), as well as its impact on the functional and radiological outcomes after total knee arthroplasty (TKA) with patellar resurfacing.

METHODS

A prospective randomized study was designed. It included patients scheduled for a TKA procedure with patellar resurfacing, who were recruited and randomized into either the LRR group or the non-release group. 198 patients were included in the final analysis. The pressure pain threshold (PPT) assessed by pressure algometry (PA), the visual analogue scale (VAS), Feller's patellar score, the Knee Society Score (KSS), patellar height, and patellar tilt were recorded both preoperatively and at the 1-year follow-up. The Mann-Whitney U test was performed to determine comparisons between both groups as well as to determine differences' intragroup.

RESULTS

Relative to the clinical variables and scores, no difference was detected between the two groups at the 1-year follow-up (p = n.s.). However, there was a slight difference in patellar tilt (0.1º vs. 1.4º, p = 0.044), with higher tilt values in the non-release group. There was no difference in terms of improvement in the clinical and radiological scores and variables recorded between the two groups (p = n.s.).

CONCLUSION

LRR in primary TKA with patellar resurfacing does not show an improvement in AKP and functional outcomes over patellar resurfacing without release.

LEVEL OF EVIDENCE

I.

Navigated functional alignment total knee arthroplasty achieves reliable, reproducible and accurate results with high patient satisfaction

PURPOSE

The decision on which technique to perform a total knee arthroplasty (TKA) has become more complicated over the last decade. Perceived limitations of mechanical alignment (MA) and kinematic alignment (KA) have led to the development of the functional alignment (FA) philosophy. This study aims to report the 2-year results of an initial patient cohort in terms of revision rate, PROMs and complications for Computer Aided Surgery (CAS) Navigated FA TKA.

METHODS

This paper reports a single surgeon's outcomes of 165 consecutive CAS FA TKAs. The final follow-up was 24 months. Pre-operative and post-operative patient-reported outcome measures, WOMAC and KSS, and intra-operative CAS data, including alignment, kinematic curves, and gaps, are reported. Stress kinematic curves were analysed for correlation with CAS final alignment and CAS final alignment with radiographic long-leg alignment. Pre- and post-operative CPAK and knee phenotypes were recorded. Three different types of prostheses from two manufacturers were used, and outcomes were compared. Soft tissue releases, revision and complication data are also reported.

RESULTS

Mean pre-operative WOMAC was 48.8 and 1.2 at the time of the final follow-up. KSS was 48.8 and 93.7, respectively. Pre- and post-operative range of motion was 118.6° and 120.1°, respectively. Pre-operative and final kinematic curve prediction had an accuracy of 91.8%. CAS data pre-operative stress alignment and final alignment strongly correlate in extension and flexion, r = 0.926 and 0.856, p < 0.001. No statistical outcome difference was detected between the types of prostheses. 14.5% of patients required soft tissue release, with the lateral release (50%) and posterior capsule (29%) being the most common.

CONCLUSION

CAS FA TKA in this cohort proved to be a predictable, reliable, and reproducible technique with acceptable short-term revision rates and high PROMs. FA can account for extremes in individual patient bony morphology and achieve desired gap and kinematic targets with soft tissue releases required in only 14.5% of patients.

LEVEL OF EVIDENCE

IV (retrospective case series review).

Factors that impact the patellofemoral contact stress in the TKA: a review

Abnormal retro patellar stress is believed to contribute to patellofemoral complications after total knee arthroplasty (TKA), but the causal link between TKA and patellofemoral contact stress remains unclear. By reviewing the relevant studies, we found that both TKA implantation and additional patellar resurfacing increase retro patellar pressure. The rotation and size of the femoral component, thickness and position of the patellar component, installation of the tibial component, prosthesis design and soft tissue balance further influence patellofemoral stress. Specific measures can be applied to reduce stress, including the installation of the femoral prosthesis with an appropriate external rotation angle, placing the tibial component at a more posterior position and the patellar button at a more medial position, avoiding over-sized femoral and patellar components, selecting posterior-stabilized design rather than cruciate-retaining design, using gender-specific prosthesis or mobile-bearing TKA system, and releasing the lateral retinaculum or performing partial lateral facetectomy. Despite these measures, the principle of individualization should be followed to optimize the patellofemoral biomechanics.

Overview of Randomized Controlled Trials in Total Knee Arthroplasty (47,675 Patients): What Have We Learnt?

BACKGROUND

The aim of this study is to provide an overview of randomized controlled trials (RCTs) in primary total knee arthroplasty summarizing the available high-quality evidence.

METHODS

Following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we searched the Cochrane Central Register of Controlled Trials (CENTRAL, 2019, Issue 3), Ovid MEDLINE, and Embase. We excluded nonrandomized trials, trials on unicompartmental knee arthroplasty or revision surgery, systematic reviews, and meta-analyses. Trials that met our inclusion criteria were assessed using a binary outcome measure of whether they reported statistically significant findings. These were then classified according to the intervention groups (surgical approach, tourniquet use, design, etc.).

RESULTS

Four hundred and three RCTs met the inclusion criteria and were included. The total number of patients in those 403 RCTs was 47,675. Only 33 RCTs (8.2%) reported significant differences between the intervention and the control groups. The trials were grouped into surgical approach 34, tourniquet 31, minimally invasive surgery 13, patient specific instrumentation 30, knee design 37, fixation 27, mobile bearing 47, navigation 50, polyethylene 19, technique 27, patella resurfacing 26, drain 19, closure 16, and others 27 RCTs.

CONCLUSION

For the vast majority of patients, a standard conventional total knee arthroplasty with a surgical approach familiar to the surgeon using standard well-established components, with or without tourniquet, without surgical drain leads to satisfactory long-term clinical outcomes.

Understanding the patellofemoral joint in total knee arthroplasty

Total knee arthroplasty (TKA) is one of the most successful procedures in orthopedic surgery. Nevertheless, postoperative patellofemoral complications remain a challenging problem, affecting a substantial proportion of patients. Complications involving the patellofemoral joint (PFJ) can occur in both resurfaced and nonresurfaced patellae. Types of PFJ complications include anterior knee pain, maltracking, fracture, avascular necrosis and patellar clunk. The causes of patellofemoral complications can be categorized into patient-, surgeon- and implant-related factors. Patient characteristics such as female sex, young age, depression and increased body mass index have been linked with increased complications. Important technical considerations to avoid complications include achieving appropriate rotational alignment of the femoral and tibial components, maintaining joint line height, medializing the patellar button and avoiding “overstuffing” the PFJ. Component design features such as conformity, shape and depth of the femoral trochlea have also been shown to be important. Although the cause of patellofemoral complications after TKA may sometimes be unknown, it remains important to minimize errors that can lead to these complications.

[Influence of lateral retinacular release on anterior knee pain following total knee arthroplasty]

Objective

To investigate the effect of lateral retinacular release on the clinical outcomes after total knee arthroplasty (TKA) without resurfacing of the patella.

Methods

A prospective randomized controlled study was performed on 132 patients with unilateral degenerative knee arthritis undergoing TKA bewteen October 2012 and October 2014, who met the selection criteria. During TKA, lateral retinacular release was used in 66 cases (trial group) and was not used in 66 cases (control group). Two patients were excluded from the study due to missing the follow-up in trial group. Four patients were excluded from the study due to lateral retinacular release in control group. Finally, 64 patients and 62 patients were included in the trial group and in the control group. There was no significant difference in gender, age, body mass index, side, disease duration, preoperative patellar morphology, grading of patellofemoral arthritis, grade of patellar cartilage degeneration, patellar malposition, patellar maltracking, patellar score, and Knee Society Score (KSS) between 2 groups ( P>0.05). The operation time, postoperative drainage volume, hospitalization time, postoperative complications, and patient satisfaction were recorded. Postoperative anterior knee pain was assessed by visual analogue scale (VAS), and the knee joint function was evaluated by KSS score and patellar score. The femoral angle, tibial angle, femoral flexion angle, and tibial posterior slope angle were measured on the X-ray film for postoperative prosthetic alignment. The postoperative patellar tracking and patellar position, as well as the presence of osteolysis, prosthesis loosening, patellar fracture and patellar necrosis were observed.

Results

All patients were followed up for 24 months. There was no significant difference in operation time, postoperative drainage volume, hospitalization time, and patient satisfaction between 2 groups ( P>0.05). The incidence of anterior knee pain in the trial group was better than that in the control group ( P=0.033). KSS score and patellar score were significantly improved in both groups at 24 months after operation when compared with preoperative scores ( P<0.05), but no significant difference was found between 2 groups ( P>0.05). Complications included hematoma (2 cases in the trial group, and 1 case in the control group), mild wound dehiscence (2 cases in each group respectively), skin-edge necrosis (1 case in the trial group), and superficial wound infection (1 case in each group respectively), which were cured by conservative treatment. No patellar necrosis, patella fracture, or knee lateral pain occurred in 2 groups. There was no significant difference in complication rate between groups ( P=0.392). Satisfactory implant alignment was observed in both groups during follow-up. There was no significant difference in femoral angle, tibial angle, femoral flexion angle, and tibial posterior slope angle between 2 groups ( P>0.05). No radiolucent line at the bone-implant interface was seen around the tibial components and femoral components in both groups. The patellar maltracking was observed in 3 patients of the trial group and 5 patients of the control group, showing no significant difference ( P=0.488). However, the incidence of patellar malposition in the trial group (18.8%) was significantly lower than that in the control group (35.5%) ( χ²=0.173, P=0.034).

Conclusion

Lateral retinacular release during primary TKA without resurfacing of the patella can reduce postoperative knee pain without increasing complications.

Different Factors Conduct Anterior Knee Pain Following Primary Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

A systematic review and meta-analysis was performed to investigate the risks associated with anterior knee pain (AKP) following primary total knee arthroplasty (TKA).

METHODS

A computerized search was performed of the following databases: MEDLINE, Embase, and Cochrane Central (published prior to July 2017). A total of 37 studies, which included 1641 cases of AKP and 168,090 TKAs, were included in the meta-analysis.

RESULTS

A subgroup analysis revealed that compared with those without the following medical conditions, patients who had an infrapatellar fat pad excision and more than 12 months of follow-up (odds ratio [OR] 12.58, 95% confidence interval [CI] 3.245-48.781) were more likely to have AKP after TKA. Circumpatellar electrocautery (>12 months: OR 0.50, 95% CI 0.326-0.760; ≤12 months: OR 0.59, 95% CI 0.408-0.867) and patellar resurfacing (OR 0.25, 95% CI 0.131-0.485) may decrease the risk of AKP. Other factors, including the prosthesis bearing type (mobile bearing or fixed bearing) and the approach (midvastus compared with the medial parapatellar approach), were not significant risk factors for AKP.

CONCLUSION

The use of strategies such as patellar denervation and patellar resurfacing in primary TKA is recommended because they are safe and result in good clinical outcomes in preventing AKP. Caution should be taken when using an infrapatellar fat pad excision, because there is an increased risk of AKP at long-term follow-up (>12 months). Future studies should investigate these different strategies to confirm the underlying mechanisms and help prevent the occurrence of AKP after TKA. The timing of AKP onset remains unclear and requires further research.

REPLACEMENT VERSUS NON-REPLACEMENT OF THE PATELLAR JOINT SURFACE IN TOTAL KNEE ARTHROPLASTY

Objective

This study addresses functional data, pain, and the reoperation rate in patients undergoing primary total knee arthroplasty (TKA) during which the patella was or was not replaced.

Methods

Fifty-three knees were included, 18 with the patella replaced and 35 with the patella not replaced. WOMAC and SF-12 scores and knee pain were analyzed preoperatively and 3, 6, and 12 months after TKA. The reoperation rate was also evaluated.

Results

Both groups presented significant improvement in WOMAC score and pain at all postoperative follow-up appointments. There was no significant difference between the groups in all evaluated variables. Two subjects in the group did not undergo patellar replacement due to complaints of anterior knee pain after arthroplasty. There was no difference between the groups in relation to the reoperation rate.

Conclusion

Patients receiving patellar replacement during TKA did exhibit significant differences in the rate of reoperation, function, or pain when compared to patients in which the patella was replaced. Level of Evidence III; Cohort study.

[A comparative study on effectiveness of patellar resurfacing against non-resurfacing in total knee arthroplasty]

Objective

To investigate the effectiveness of total knee arthroplasty (TKA) with or without patellar resurfacing.

Methods

Between March 2013 and August 2015, 30 patients (60 knees) with osteoarthritis who met the inclusion criteria were recruited in the study. Of 30 cases, 24 were male and 6 were female with an average age of 57.2 years (range, 37-65 years). The body mass index ranged from 19.5 to 40.3 kg/m ² (mean, 28.2 kg/m ²). According to Kellgren-Lawrence grading, there were 8 cases at grand Ⅲ and 22 cases at grand Ⅳ. All patients underwent primary bilateral TKA. The patellar resurfacing was done at the unilateral knee randomly (resurfacing side); the opposite treatment was done at the other side (non-resurfacing side). The indexes of 2 groups were recorded and compared, including the intraoperative blood loss, operation time, knee society score (KSS), "Forgotten Joint" scale (FJS), anterior knee pain, anterior patellar spirant, knee constraint feeling, anterior patellar clunk, muscle power of knee extension, and ability of up and down stairs, weight-bearing flexion, squatting down, cross-legged, knee down, knee extension, and patient satisfaction. Radiographic examination was used to analyze the prosthesis position.

Results

The operation time were (126±14) minutes and (112±11) minutes in resurfacing side and non-resurfacing side, respectively, showing significant difference between two sides ( t=5.103, P=0.030); and there was no significant difference in intraoperative blood loss between two sides ( t=3.431, P=0.800). All patients were followed up 2-4 years (mean, 2.6 years). There was no significant difference ( P>0.05) between two sides in KSS clinical and functional scores at preoperation and 6 weeks, 6 months, and 2 years after operation; in visual analogue scale (VAS) score of anterior knee pain at preoperation and 6 weeks after operation; in incidences of anterior patellar spirant, knee constraint feeling, anterior patellar clunk, and muscle power of knee extension at 6 weeks, 6 months, and 2 years after operation; in incidences of disability of up and down stairs, weight-bearing flexion, squatting down, cross-legged, knee down, and knee extension at 6 weeks, 6 months, and 2 years after operation; in ratio of FJS score at 2 years after operation. The VAS scores at 6 months and 2 years after operation in resurfacing group were significantly lower than those in non-resurfacing group ( Z=-1.997, P=0.046; Z=-2.197, P=0.028). Patient satisfaction of resurfacing side was superior to the non-resurfacing side at 6 weeks after operation ( χ²=4.271, P=0.039). Radiographic examination showed no prosthesis loosing occurred.

Conclusion

The effectiveness of TKA with patellar resurfacing is better than that with non-resurfacing in patients satisfaction.

A lateral retinacular release during total knee arthroplasty changes femorotibial kinematics: an in vitro study

INTRODUCTION

Lateral retinacular release (LRR) is a common procedure during total knee arthroplasty (TKA), especially if patellar maltracking is observed intraoperatively. The impact of LRR on patellofemoral kinematics is well-examined, but the influence on femorotibial kinematics requires more elucidation. Therefore, the aim of this study was to evaluate the effects of LRR on femorotibial kinematics in vitro.

MATERIALS AND METHODS

A fixed bearing TKA was implanted in six human knee specimens. Femorotibial kinematics were measured dynamically through the use of a custom-constructed knee rig which flexes the knee from 20° to 120° under weight bearing conditions. Measurements were performed before and after LRR. LRR was performed completely including transection of synovium, retinaculum and tractus fibers. For the registration of tibiofemoral kinematics a 3-dimensional-ultrasound-based motion analysis system was used.

RESULTS

LRR revealed a significant reduction of femoral rollback at the lateral compartment (9.4 ± 5.0 vs 7.8 ± 9.4 mm; p < 0.01), whereas the present decrease of femoral rollback at the medial compartment was not significant (3.4 ± 4.7 vs 2.3 ± 5.9 mm; p = 0.34). Accordingly, LRR significantly reduced internal rotation of the tibia (0.8°; p < 0.01).

CONCLUSION

The results suggest that LRR significantly decreases lateral femoral rollback as well as internal rotation of the tibia, probably by changing the tension of the iliotibial band. When performing a LRR in clinical routine, surgeons should be aware of altering not only patellofemoral kinematics but also the femorotibial kinematics.

Comparison of patellofemoral outcomes after TKA using two prostheses with different patellofemoral design features

PURPOSE

The purpose of the present study was to compare the clinical and radiographic results after TKA using two prostheses with different sagittal patellofemoral design features, including outcomes related to compatibility of the patellofemoral joint.

METHODS

The clinical and radiographic results of 81 patients (100 knees) who underwent TKA using the specific prosthesis (group A) were compared with those in a control group who underwent TKA using the other prosthesis (group B). The presence of anterior knee joint pain, patellar crepitation, and patellar clunk syndrome was also checked.

RESULTS

The function score and maximum flexion angle at the last follow-up were slightly better in group A than those in group B (92.0 ± 2.3 vs. 90.6 ± 4.2) (133.6° ± 8.4° vs. 129.6° ± 11.4°). Anterior knee pain was observed in 6 knees and patellar crepitation in four knees in group A. In group B, these symptoms were observed in 22 knees and 18 knees, respectively. There was no patellar clunk syndrome in either group. The alignment was corrected with satisfactory positioning of components. The patellar height remained unchanged after TKA in the two groups. The differences between preoperative and postoperative patellar tilt angle and patellar translation were small.

CONCLUSION

When comparing the clinical and radiographic results after TKA using two prostheses with different sagittal patellofemoral design features, TKA using the specific prosthesis provided satisfactory results with less clinical symptoms related to the patellofemoral kinematics with TKA using the other prosthesis.

LEVEL OF EVIDENCE

III.

Mechanical alignment technique for TKA: Are there intrinsic technical limitations?

BACKGROUND

Mechanically aligned (MA) total knee arthroplasty (TKA) is affected by disappointing functional outcomes in spite of the recent improvements in surgical precision and implant designs. This might suggest the existence of intrinsic technical limitations. Our study aims to compare the prosthetic and native trochlear articular surfaces and to estimate the extent of collateral ligament imbalance, which is technically uncorrectable by collateral ligament release when TKA implants are mechanically aligned.

STUDY HYPOTHESIS

Conventional MA technique generates a high rate of prosthetic overstuffing of the distal groove, distal lateral trochlear facet and distal lateral femoral condyle (Hypothesis 1), and technically uncorrectable collateral ligament imbalance (hypothesis 2)? Disregarding the distal femoral joint line obliquity (DFJLO) when performing femoral cuts explains distal lateral femoral prosthetic stuffing and uncorrectable imbalance (hypothesis 3)?

METHODS

Twenty patients underwent a conventional MA TKA. Pre-operative MRI-based 3D knee models were generated and MA TKA was simulated. Native and prosthetic trochlear articular surfaces were compared using in-house analysis software. Following the automatic determination by the planning software of the size of the extension and flexion gaps, an algorithm was applied to balance the gaps and the frequency and amplitude of technically uncorrectable knee imbalance were estimated.

RESULTS

The conventional MA technique generates a significant slight distal lateral femoral prosthetic overstuffing (mean 0.6mm, 0.8mm, 1.25mm for the most distal lateral facet point, groove, and at the most distal point of lateral femoral condyle, respectively) and a high rate of type 1 and 2 uncorrectable knee imbalance (30% and 40%, respectively). The incidence of distal lateral prosthetic overstuffing (trochlea and condyle) and uncorrectable knee imbalance were strongly to very strongly correlated with the DFJLO (r=0.53 to 0.89).

CONCLUSION

Conventional MA technique for TKA generates frequent lateral distal femoral prosthetic overstuffing and technically uncorrectable knee imbalance secondary to disregarding the DFJLO when adjusting the femoral component frontal and axial rotations, respectively.

LEVEL OF EVIDENCE

level 4.

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.

[Effectiveness of acetabular revision using a metal reconstruction cage]

Objective

To explore the clinical outcomes of acetabular revision using a metal reconstruction cage.

Methods

Between October 2006 and October 2013, 16 patients (16 hips) underwent acetabular revision with a metal reconstruction cage. There were 4 males and 12 females, with the mean age of 62.7 years (range, 49-78 years). The time from total hip arthroplasty to revision was 3-15 years (mean, 8.2 years). The causes for revision were aseptic acetabular loosening in 15 cases, and femoral periprosthetic fracture (Vancouver type B3) in 1 case. According to the American Academy of Orthopaedic Surgeons (AAOS) classification, there were 12 cases of type III and 4 cases of type IV; according to the Paprosky classification, there were 12 cases of type IIIA and 4 cases of type IIIB. Harris score was used for hip function evaluation, and visual analogue scale (VAS) for pain in the thigh. X-ray films were taken for imaging evaluation.

Results

Healing of incision by first intention was obtained in all patients. Deep venous thrombosis occurred in 1 patient, and was cured after anticoagulation therapy. No complications of infection, neurovascular injury, and prosthetic dislocation were found. Sixteen patients were followed up 6.8 years on average (range, 2-9 years). The Harris score was significantly increased from preoperative 42.44±4.66 to 91.88±3.28 at last follow-up ( t=-106.30, P=0.00). Two patients had mild pain in the thigh, but pain disappeared at 1 year after operation. At immediate after operation, the abduction angle was 37-54° (mean, 42.9°). The distance between acetabular rotation centre and teardrop line was (33.67±12.19) mm for preoperative value and was (20.67±9.63) mm for postoperative value, showing significant difference ( t=-9.60, P=0.00). The distance between acetabular rotation centre and lateral teardrop was (34.98±12.30) mm for preoperative value and was (40.04±6.61) mm for postoperative value, showing significant difference ( t=-3.15, P=0.00). X-ray film results showed bony fusion at the osteotomy sites at 4 to 12 months after operation. No continuous radiolucent line, prosthetic dislocation, or osteolysis was found, and bony ingrowth was observed in all patients. No patient received re-revision due to prosthetic loosening.

Conclusion

The metal reconstruction cage for acetabular revision can achieve good effectiveness for patients with serious bone defect.

Is patellar denervation necessary in total knee arthroplasty without patellar resurfacing?

PURPOSE

To conduct a meta-analysis with randomized controlled trials (RCTs) published in full text to determine the effectiveness of patellar denervation (PD) in primary total knee arthroplasty (TKA).

METHODS

Literature search was performed in PubMed, Embase, Web of Science and Cochrane Library for information from the earliest date of data collection to February 2015. RCTs comparing the benefits and risks of PD with those of no patellar denervation (NPD) in primary TKAs were included. Statistical heterogeneity was quantitatively evaluated by X(2) test with the significance set P < 0.10 or I (2) > 50 %.

RESULTS

Six RCTs consisting of 751 patients were included. The incidences of AKP in PD group and NPD group were 38.3 % (90/235) and 46.3 % (107/231), respectively. Meta-analysis showed significant prevention effect of PD on the incidence of AKP (OR 0.65; 95 % CI 0.42, 1.00; P = 0.05) without significant heterogeneity (I (2) = 44 %, P = 0.15). Our results also indicated that PD was significantly associated with better American Knee Society knee (WMD = 2.50; 95 % CI 0.34, 4.67; P = 0.02) and functional scores (WMD = 4.07; 95 % CI 1.34, 6.80; P = 0.0003) and range of motion (ROM) (WMD = 4.27; 95 % CI 1.95, 6.60; P = 0.0003) compared with NPD. However, there was no significant difference between the two groups no matter in Oxford knee score, patellar score or visual analogue scale at any other time. Complications and revisions did not differ significantly between the two groups.

CONCLUSION

This meta-analysis showed that PD in TKAs without patellar resurfacing, compared with NPD, could prevent the incidence of post-operative AKP and improve clinical outcome in KSS and post-operative ROM. Based on the above results, PD was a safe procedure with no significant complications and revision or re-operations.

LEVEL OF EVIDENCE

Therapeutic study, Level II.

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.

Partial lateral patellar facetectomy as an alternative to lateral release in Total Knee Arthroplasty (TKA)

This study presents the selective use of partial patellar lateral facetectomy for maltracking during primary TKA, as an alternative to lateral release. Twenty three partial facetectomies were performed out of 191 TKAs (12%). Balanced tracking was achieved in 22 knees. At follow-up 2 patients had persistent anterior knee pain. Mean Knee Society score (KSS) was 94 and mean functional KSS was 86. Mean patellar score was 28. Patellar tilt angles were within 2 degrees in all but one knee. Patellar translation was within 2 mm in all cases. No complications were recorded. A control group of 46 matched patients had similar functional and radiographic results. If tracking is not satisfactory at the conclusion of TKA, our method of choice would be partial lateral facetectomy.

Collagen nanofibers facilitated presynaptic maturation in differentiated neurons from spinal-cord-derived neural stem cells through MAPK/ERK1/2-Synapsin I signaling pathway

Neural stem cells (NSCs) are deemed to be a potential cell therapy for brain and spinal cord reconstruction and regeneration following injury. In this study, we investigated the role of nanofibrous scaffolds on NSCs-derived neurons in the formation of neural networks. Miniature excitatory postsynaptic currents (mEPSCs) were recorded using the whole-cell patch clamp recording method after the spinal cord-derived NSCs were differentiated into neurons and cultured in vitro for 10-14 days. It was observed that the frequency of mEPSCs in the differentiated neurons cultured on both randomly oriented and aligned collagen nanofibrous scaffolds was higher than that on the collagen-coated control and can be inhibited by an ERK inhibitor (PD98059), indicating that the collagen nanofibers affected the maturation of the synapses from presynaptic sites via the MAPK/ERK1/2 pathway. In addition, both of the collagen nanofibers increased the phosphorylation of Synapsin I and facilitated the interaction of p-ERK1/2 and p-Synapsin I. All these results suggested that the collagen nanofibrous scaffolds contributed to the presynaptic maturation via the ERK1/2-Synapsin I signaling pathway.