The pie-crusting technique using a blade knife for medial collateral ligament release is unreliable in varus total knee arthroplasty

Precision soft tissue balancing: grid-assisted pie-crusting in total knee arthroplasty

Introduction

The varus and valgus knee deformities result from imbalance in tension between medial and lateral soft tissue compartments. These conditions need to be addressed during total knee arthroplasty (TKA). However, there is no consensus on optimal soft-tissue release techniques for correcting varus and valgus deformities during TKA. We assessed the efficacy of a novel grid-based pie-crusting technique on soft-tissue release.

Methods

Cadaver knees were dissected, leaving only the femur and tibia connected by an isolated MCL or the femur and fibula connected by an isolated LCL. Bone cuts were made as performed during primary TKA. Mechanical testing was performed using an MTS machine. A 3D-printed 12-hole grid was placed directly over the MCL and LCL. Using an 18-gauge needle, horizontal in-out perforations were made 3 mm apart. Deformation and stiffness of the ligaments were collected after every 2 perforations. Means were calculated, and regression analyses were performed.

Results

A total of 7 MCL and 6 LCL knees were included in our analysis. The mean medial femorotibial (MFT) space increased from 6.018 ± 1.4 mm-7.078 ± 1.414 mm (R2 = 0.937) following 12 perforations. The mean MCL stiffness decreased from 32.15 N/mm-26.57 N/mm (R2 = 0.965). For the LCL group, the mean gap between the femur and fibula increased from 4.287 mm-4.550 mm following 8 perforations. The mean LCL stiffness decreased from 29.955 N/mm-25.851 N/mm. LCL stiffness displayed a strong inverse relationship with the number of holes performed (R2 = 0.988).

Discussion

Our results suggest that using this novel grid for pie-crusting of the MCL and LCL allows for gradual lengthening of the ligaments without sacrificing their structural integrity. Our proposed technique may serve as a valuable piece in the soft-tissue release toolkit for orthopaedic surgeons performing TKA in varus and valgus deformed knees.

Exploring the extension quantities of a medial collateral ligament pie-crusting model using a finite element method

Medial collateral ligament (MCL) pie-crusting can balance the soft tissue during total knee arthroplasty but requires more studies with the finite element method (FEM). We have developed three models of MCL pie-crusting utilizing FEM, treating the MCL in the following ways: (1) as a singular elastic body with both ends attached to the bone (model A), (2) as 19 bundled elastic bodies, each attached to both ends of the bone (model B), and (3) as 19 bundled elastic bodies with an adhesive component in the gap, attached to both ends of the bone (model C). The pie-crusting model was created by adding a cut around the center of each model. The left side of the model was fixed and forces of 80 and 120 N in the positive direction of the x-axis were applied. Model A was extended by 0.0068 and 0.010 mm for approximately 10 punctures. Model B-2 was extended by 1.34 and 2.01 mm, approximately twice as much as model B-1. Model C was extended by 0.34 and 0.50 mm for every 10 punctures added. These findings clarify that the model composed of aggregates of fibers with adhesive parts (model C) is suitable for MCL pie-crusting analysis.

Complete Release of the Superficial Medial Collateral Ligament in Total Knee Arthroplasty

Background

Proper soft-tissue balance was essential in total knee arthroplasty (TKA). Superficial medial collateral ligament (sMCL) release has been recommended in correction of severe varus knee. However, it has concerns of overcorrection. This study aimed to analyze coronal plane laxity in sMCL-released TKA patients.

Methods

We prospectively collected data from TKA patients who were operated from January 2015 to November 2018. All patients went through the same surgical steps; however, sMCL was left intact in mild-to-moderate deformity (sMCL-intact), while it was completely released in patients with severe deformity (sMCL-released). All patients went through the same postoperative protocol. We used stress radiograph with 90 N force to evaluate coronal plane laxity and recorded modified Western Ontario and McMaster Universities Osteoarthritis Index score at 3- to 6-year postoperative appointments.

Results

There were 46 patients (59 knees) included with an average follow-up time of 48.3 months. The sMCL-intact group consisted of 14 patients (16 knees) with average preoperative mechanical axis (MA) varus of 4.84 degrees exhibited 1.64 mm (0.6-3.6 mm) laxity on medial side and 1.01 mm (0-3.1 mm) on lateral side. The sMCL-released group consisted of 32 patients (43 knees) with average preoperative MA varus of 14.74 degree exhibited 1.96 mm (0.4-4.8 mm) laxity on medial side and 1.57 mm (0.1-5.9 mm) on lateral side. At the time of follow-up, the mean modified Western Ontario and McMaster Universities Osteoarthritis Index in the sMCL-intact and sMCL-released groups were 14.8 and 13.5 (P value .79), respectively. There was no clinical laxity or reoperation of any causes in either groups.

Conclusions

Complete release of sMCL in severe varus knee does not result in overcorrection after TKA at the midterm follow-up period. Thus, sMCL release technique could be an effective and safe option for correction of severe varus deformity.

Using sequential bone cutting to titrate soft tissue balance in total knee arthroplasty effectively minimizes soft tissue release

BACKGROUND

Achieving soft tissue balance while maintaining limb alignment within acceptable boundaries is crucial for successful total knee arthroplasty (TKA). We proposed a sequential bone cutting (SBC) technique to titrate the soft tissue balance in robot-assisted TKA to achieve the desired balance with minimum soft tissue release.

METHODS

In total, 106 robot-assisted TKAs using the SBC technique were included. The preoperative hip-knee-ankle angle (HKA) was < 10° in 76 and ≥ 10° in 30 knees. The gaps were initially balanced with the help of the pre-resection balancing provided by the robotic system. Soft tissue balance and alignment were quantitatively measured after the initial bone cutting and final bone cutting. Additional adjustments (bone recuts and soft tissue releases) required to address soft tissue imbalance after initial bone cutting were recorded. The frequencies of soft tissue releases, soft tissue balance, and resultant alignment ≤ 3° were compared between non-severe (HKA < 10°) and severe deformity (HKA ≥ 10°) groups.

RESULTS

Soft tissue balance was achieved in 45 knees (42.5%) after initial bone cutting and in 93 knees (87.7%) after final balancing. The postoperative alignment was within 3° from neutral in 87 knees (82.1%) and 3-5° in 17 knees (16.0%). For unbalanced knees (n = 61) after initial bone cutting, soft tissue release was avoided by SBC in 37 knees (60.7%) and was deemed necessary in 24 knees (39.3%). Soft tissue release was more likely to be avoided in the non-severe deformity cohort (86.8% [33 of 38]) than in the severe deformity cohort (17.4% [4 of 23]; p < 0.001). The non-severe deformity cohort showed a significantly higher rate of resultant alignment ≤ 3° from neutral than the severe deformity cohort (90.8% vs. 60.0%; p < 0.001).

CONCLUSION

Pre-resection balancing is inappropriate to ensure soft tissue balance. The SBC technique is effective in minimizing soft tissue release while maintaining overall alignment within acceptable boundaries.

Risk Factors and Preventive Strategies for Perioperative Distal Femoral Fracture in Patients Undergoing Total Knee Arthroplasty

Background and Objectives Perioperative distal femoral fracture is rare in patients undergoing total knee arthroplasty (TKA). In such rare cases, additional fixation might be required, and recovery can be delayed. Several studies have focused on perioperative distal femoral fractures in TKA, but there remains a lack of information on risk factors. The purpose of this study was to investigate risk factors for perioperative distal femoral fractures in patients undergoing TKA and suggest preventive strategies. Materials and Methods: This retrospective study included a total of 5364 TKA cases in a single institution from 2011 to 2022. Twenty-four distal femoral fractures occurred during TKA or within one month postoperatively (0.45%). Patient demographics, intraoperative findings, and postoperative progress were obtained from patient medical records and radiographs. Risk factors for fractures were analyzed using multivariate Firth logistic regression analysis. Results: Although all 24 distal femoral fractures occurred in female patients (24 of 4819 patients, 0.50%), the incidence rate of fracture between male and female patients was not significantly different (p = 0.165). The presence of osteoporosis and insertion of a polyethylene (PE) insert with knee dislocation were statistically significant risk factors (p = 0.009 and p = 0.046, respectively). However, multivariate logistic regression analysis showed that only osteoporosis with bone mineral density (BMD) < -2.8 (odds ratio (2.30), 95% CI (1.03-5.54), p = 0.043) was an independent risk factor for perioperative distal femoral fracture in TKA patients. Conclusions: Our results suggest that osteoporosis with BMD < -2.8 is a risk factor for distal femoral fractures in patients undergoing TKA. In these patients, careful bone cutting, adequate gap balancing, and especially the use of the sliding method for insertion of a PE insert are recommended as preventive strategies.

Combining load sensor and robotic technologies for ligament balance in total knee arthroplasty

Good ligament balance in total knee arthroplasty (TKA) is thought to improve clinical results, but is highly surgeon-dependent when performed without technological assistance. We therefore describe a TKA technique using the Mako robotic arm (Stryker, Kalamazoo, Michigan, USA) as sole means of balancing ligament tension by bone recuts associated to control by the VERASENSE load sensor (Orthosensor, Inc, Dania Beach, Florida, USA). In this preliminary series of 29 patients, 27 (93%) showed a well-balanced knee in extension at end of procedure, and 23 (79%) showed a well-balanced knee in flexion and extension, without any periarticular soft-tissue release. The load sensor analyzes ligament balance after the initial bone cuts, and guides possible further femoral or tibial recuts. This technique enables quantifiable alignment and control of ligament tension. Collecting objective intraoperative data should improve knowledge in placing TKA prostheses.

Comparison of Outcomes After Total Knee Arthroplasty Involving Postoperative Neutral or Residual Mild Varus Alignment: A Systematic Review and Meta-analysis

Comparing mainly clinical and functional outcomes as well as prosthesis survival with neutral and residual mild varus alignment, we searched PubMed, Embase, Cochrane Library and Web of Science databases from 1 January 1974 to 18 December 2020 to identify studies comparing clinical and functional outcomes as well as prosthesis survival in the presence of different alignments after total knee arthroplasty (TKA) for varus knees. The included studies were assessed by two researchers according to the Newcastle–Ottawa Scale (NOS). Postoperative neutral alignment (0° ± 3°) was compared to residual mild varus (3°–6°) and residual severe varus (>6°). Meta‐analysis was performed using Review Manager 5.3. The odds ratios (OR) and mean differences (MD) were used to compare dichotomous and continuous variables. The fixed‐effect model and random‐effect model were used to meta‐analyze the data. Nine studies were included in the meta‐analysis with 1410 cases of postoperative neutral alignment, 564 of residual mild varus alignment and 175 of residual severe varus alignment following TKA, all of which were published after 2013. Three studies scored 7 points on the NOS, while the remaining studies scored 8 points, suggesting high quality. The pooled mean differences (MDs) of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score were 1.07 [95% confidence interval (CI) −1.06 to 3.20; P = 0.32; I² = 79%]. The meta‐analysis showed that neutral alignment and mild varus alignment were associated with similar the Oxford Knee Score (OKS), Knee Society Knee Score (KS‐KS), and Knee Society Function Score (KS‐FS), while neutral alignment was associated with lower Forgotten Joint Score (FJS) [mean difference −6.0, 95% confidence interval (CI) −9.37 to −2.64, P = 0.0005]. Neutral alignment was associated with higher KS‐KS than severe alignment (M 2.98, 95% CI 1.42 to 4.55, P = 0.0002; I² = 0%) as well as higher KS‐FS (M 8.20, 95% CI 4.58 to 11.82, P < 0.00001; I² = 0%). Neutral alignment was associated with similar rate of survival as mild varus alignment (95% CI 0.36 to 9.10; P = 0.48; I² = 65%) or severe varus alignment (95% CI 0.94 to 37.90; P = 0.06; I² = 61%). There was no statistical difference in others. Residual mild varus alignment after TKA may lead to similar or superior outcomes than neutral alignment in patients with preoperative varus knees, yet the available evidence appears to be insufficient to replace the current gold standard of neutral alignment. Severe varus alignment should be avoided.

Recognizing the Role of the Posterolateral Corner in Patients Undergoing Total Knee Arthroplasty for Fixed Varus Deformity

Purpose

Varus deformity is the commonest presentation of the arthritic knee requiring surgical intervention. While correctable deformities lend themselves to realignment options like unicompartmental replacement, fixed deformities often need a total knee replacement. Current treatment options for patients with fixed coronal varus malalignment undergoing total knee arthroplasty include varying degrees of medial soft tissue releases, often leading to infringement of the medial collateral ligament complex and increased use of constrained options. We describe the role of the posterolateral (PL) tether in a select subgroup of patients needing release to achieve correction and minimising use of constrained options.

Patients and Methods

A total of 384 patients with fixed varus deformity were retrospectively evaluated and categorised on the basis of weight bearing x-rays into four groups, namely, knees with angulation (F1), angulation with subluxation and torsion (F2), medial translation (F3) and deformity with major medial bone loss (F4). From this cohort, we identified patients with a tight PL tether that needed release to achieve good correction. These were predominantly in the F2 and F3 subgroups. Functional scores and outcomes were evaluated at a mean follow-up of 120.23 months.

Results

F1 cohort achieved good correction with medial soft tissue release, while F2 and F3 cohorts often needed a PL release. While functional outcomes and scores were comparable in both groups, survivorship was better in the group where release was done.

Conclusion

We recognise the role of the PL tether in a subgroup of patients with recalcitrant fixed varus deformities. Sequential release helped achieve good outcomes with minimal use of constrained options.

Level of Evidence

Three.

Intraoperative repair for iatrogenic MCL tear due to medial pie-crusting in TKA yields satisfactory mid-term outcomes

PURPOSE

This study aimed to assess the rate of iatrogenic mid-substance superficial medial collateral ligament (sMCL) tear due to the medial pie-crusting technique during varus deformity total knee arthroplasty and compare the knee society score (KSS), range of motion (ROM), and instability rate of the repaired group to the control group with intact sMCL.

METHODS

For this retrospective series of prospectively collected data, the multiple needle puncturing technique was performed for 653 out of the 1768 knees during algorithmic medial soft-tissue release. Iatrogenic tear was observed in 35 knees (5%); hence, repair with running locking nonabsorbable braided suture was performed. Patients were visited and reviewed both clinically and radiographically at 6 weeks, 3 months, 6 months, 12 months, and annually thereafter. Chi-square, ANOVA, Mann-Whitney, independent and paired t test were used to analyze the variables. P value < 0.05 was considered statistically significant.

RESULTS

85% of the repaired sMCL had stable joints with a mean KSS of 88 ± 3 and a mean ROM of 103 ± 11 degrees (°). The other five patients (15%) with mean KSS of 40 ± 8 and mean ROM of 81° ± 5° had an instability and needed to undergo a revision surgery. The control group had a mean KSS of 86 ± 15 and mean ROM of 107° ± 8°; however, 7 knees had an instability and needed a revision surgery. No significant difference was observed in terms of KSS (P = 0.86) and ROM (P = 0.64) between the control and repaired groups.

CONCLUSION

The mid-substance sMCL tear is an important intraoperative complication of medial pie-crusting. Repairing this iatrogenic tear with nonabsorbable suture had satisfying clinical outcomes regarding the postoperative knee ROM and KSS in comparison to the control group. However, there is a chance of failure, which should be perceived by the surgeons.

LEVEL OF EVIDENCE

Therapeutic studies, investigating the results of treatment, Level III.

Multiple needle puncture combined with repetitive knee manipulation in total knee arthroplasty for correcting varus deformity

PURPOSE

Multiple needle punctures (MNPs), for gap balancing in total knee replacement, have less variability in gap widening compared to the conventional released technique. This study aimed to evaluate the outcome of gap-balancing techniques in varus osteoarthritis (OA) knees, by serial MNP, after a total knee prosthesis trial component was placed, combined with repetitive knee manipulation.

METHODS

This study was a retrospective, case-matched study of 161 patients. The data were collected from varus OA knee patients, who had total knee arthroplasty by a single surgeon. Sixty-eight patients required MNP, combined with repetitive knee manipulation for gap balancing, and 93 patients did not. Both groups of MNP patients underwent the same surgical technique and postoperative care protocols.

RESULTS

Knee society scores, in terms of knee score and functional score, were not different in both groups when we started the study, at 6-month and 1-year follow-ups (p > 0.05). The femorotibial angle was not significantly different between groups at the start of the study, initial postoperative, 6 months, and 1 year (p = 0.74, 0.45, 0.99, and 0.82, respectively). Medial joint opening in knee radiographic was found in 3% of the patients in the MNP group and in 4% of patients in the control group at 1-year follow-up (p = 0.65).

CONCLUSION

This study found MNP combined with repetitive knee manipulation was effective, reproductive, and a safe method for varus OA knee. We believe that the cycle of performed needle punctures, knee manipulation, and reevaluation could gradually lengthen the medial soft tissue without risk of over lengthening or medial collateral ligament rupture.

[Prevention and treatment of iatrogenic medial collateral ligament injuries in total knee arthroplasty]

Objective

To summarize the prevention and treatment of iatrogenic medial collateral ligament (MCL) injuries in total knee arthroplasty (TKA).

Methods

The relevant literature about iatrogenic MCL injuries in TKA was summarized, and the symptoms, causes, preventions, and treatments were analyzed.

Results

Preventions on the iatrogenic MCL injuries in TKA is significantly promoted. With the occurrence of MCL injuries, the femoral avulsion can be fixed with the screw and washer or the suture anchors; the tibial avulsion can be treated with the suture anchors fixation, bone staples fixation, or conservative treatment; the mid-substance laceration can be repaired directly; the autologous quadriceps tendon, semitendinosus tendon, or artificial ligament can be used for the patients with poor tissue conditions or obvious residual gap between the ligament ends; the use of implant with greater constraint can be the last alternative method.

Conclusion

No consensus has been reached to the management of iatrogenic MCL injuries in TKA. Different solutions and strategies can be integrated and adopted flexibly by surgeons according to the specific situation.

Selective medial release using multiple needle puncturing with a spacer block in situ for correcting severe varus deformity during total knee arthroplasty

INTRODUCTION

We aimed to establish a selective and sequential medial release technique using multiple needle puncturing (MNP) with a spacer block in situ in severe varus deformity during total knee arthroplasty (TKA) and to investigate its efficacy and safety.

MATERIALS AND METHODS

A total of 128 patients with a varus angle >15° were included. Patients were classified according to the tightness of extension and flexion (group 1, no tightness; group 2, extension; group 3, flexion; group 4, extension and flexion). When medial tightness was found on extension, the posterior clearing procedure, including release of the posterior capsule, posterior oblique ligament, and semimembranosus, was performed sequentially. When medial tightness was found on flexion, MNP using an 18-gauge needle with a spacer block in situ was performed at the anterior portion of the superficial MCL (aMCL). Clinical and radiological evaluations including stress radiographs were performed.

RESULTS

Among 128 knees, 110 required medial release (posterior clearing procedure only in 44 [34.3%], MNP with a spacer block in situ at aMCL only in 38 [29.7%], posterior clearing procedure and MNP in 28 [21.9%]). The mediolateral gap imbalances on extension and/or flexion were significantly improved (p < 0.001 in all). There were no significant differences in clinical radiological outcomes among groups. Over-release, iatrogenic transection, and postoperative laxity on the stress radiographs were not observed.

CONCLUSION

The selective and sequential technique using posterior clearing and/or MNP with a spacer block in situ can be a reliable option for managing medial tightness in severe varus deformity during primary TKA.

A geometric ratio to predict the flexion gap in total knee arthroplasty

Measured resection is a common technique for obtaining symmetric flexion and extension gaps in posterior-stabilized (PS) total knee arthroplasty (TKA). A known limitation of measured resection, however, is its reliance on osseous landmarks to guide bone resection and component alignment while ignoring the geometry of the surrounding soft tissues such as the medial collateral ligament (MCL), a possible reason for knee instability. To address this clinical concern, we introduce a new geometric proportion, the MCL ratio, which incorporates features of condylar geometry and MCL anterior fibers. The goal of this study was to determine whether the MCL ratio can predict the flexion gaps and to determine whether a range of MCL ratio corresponds to balanced gaps. Six computational knee models each implanted with PS TKA were utilized. Medial and lateral gaps were measured in response to varus and valgus loads at extension and flexion. The MCL ratio was related to the measured gaps for each knee. We found that the MCL ratio was associated with the flexion gaps and had a stronger association with the medial gap (β = -7.2 ± 3.05, P < .001) than with the lateral gap (β = 3.9 ± 7.26, P = .04). In addition, an MCL ratio ranging between 1.1 and 1.25 corresponded to balanced flexion gaps in the six knee models. Future studies will focus on defining MCL ratio targets after accounting for variations in ligament properties in TKA patients. Our results suggest that the MCL ratio could help guide femoral bone resections in measured resection TKA, but further clinical validation is required.

The Medial Collateral Ligament in Primary Total Knee Arthroplasty: Anatomy, Biomechanics, and Injury

Understanding the anatomy and biomechanics of the medial collateral ligament (MCL) is crucial in producing good outcomes after total knee arthroplasty. A solid grasp of the surgical techniques that address the MCL are necessary to ensure good coronal plane ligament balance. Furthermore, intraoperative injury to the MCL in total knee arthroplasty is an uncommon yet serious complication which often goes unrecognized. Loss of the integrity of the MCL can lead to instability, loosening, and accelerated polyethylene wear. There is still controversy regarding the ideal method of treatment of intraoperative MCL injuries with suggested treatment modalities ranging from conservative management to use of varus-valgus constrained implants.

Arthroscopic pie-crusting release of the posteromedial complex of the knee for surgical treatment of medial meniscus injury

Background

An arthroscopic narrow posteromedial gap of the knee may cause failure of a meniscus operation. The posteromedial complex (PMC) of the knee, including the posterior part of the medial collateral ligament (MCL) and the posterior oblique ligament (POL), has a restrictive effect on the opening of the posteromedial gap of the knee in the half-extension position. Thus, we evaluated the radiological and clinical results of pie-crusting release of the PMC for arthroscopic meniscal surgery in tight knees.

Methods

Sixty patients with posterior injury of the medial meniscus were reviewed. All patients accepted arthroscopic pie-crusting release of the PMC. Fourty patients accepted meniscoplasty, and 20 patients accepted meniscal suturing. To evaluate the arthroscopic opening of the medial gap in 20° half-extension under 11-kg valgus stress, the width of the medial space before and after release were measured. During follow-up, the medial stability was evaluated by radiographic measurements of the joint space width (JSW) in 20° half-extension. Magnetic resonance imaging (MRI) was conducted to evaluate healing of the MCL and meniscus. Knee functions were evaluated using VAS (visual analogy score), Lysholm, IKDC (International Knee Documentation Committee) and Tegner scoring systems.

Results

In all patients, meniscus operations were performed without iatrogenic cartilage injury. After PMC release, the arthroscopic width of the medial space was 5.7 ± 0.5 mm, larger than that before release (2.5 ± 0.5 mm, p < 0.01). The follow-up time was 21.93 ± 7.04 months, there was no residual valgus laxity of the knee. The radiographic JSW was 5.97 ± 0.8 mm preoperatively, 9.2 ± 1.1 mm in the 1st week postoperatively, and 6.1 ± 0.9 mm by the 3rd postoperative month, showing no differences between preoperative and 3 months postoperative measurement (p > 0.05). For sutured meniscus, MRI showed healing in 15 patients while five had two-grade abnormal signals. VAS, Lysholm, IKDC and Tegner scores were 1.80 ± 0.51, 80.08 ± 3.74, 82.17 ± 4.64 and 5.48 ± 0.59, respectively, showing significant differences compared with the preoperative scores (5.57 ± 0.69, 48.17 ± 4.22, 51.42 ± 4.02 and 3.20 ± 0.68, respectively, p< 0.01).

Conclusions

Pie-crusting release of the PMC can increase the posteromedial space and improve the visual field of the knee under arthroscopy, while neither causing no residual valgus instability of the knee nor affecting the clinical outcome at the final follow-up.

Bone resection for mechanically aligned total knee arthroplasty creates frequent gap modifications and imbalances

PURPOSE

The objective of this study was to calculate bone resection thicknesses and resulting gap sizes, simulating a measured resection mechanical alignment (MA) technique for total knee arthroplasty (TKA).

METHODS

MA bone resections were simulated on 1000 consecutive lower limb CT scans from patients undergoing TKA. Femoral rotation was aligned with either the surgical trans-epicondylar axis (TEA) or with 3° of external rotation to the posterior condyles (PC). Imbalances in the extension space, flexion space, medial compartment and lateral compartment were calculated.

RESULTS

Extension space imbalances (≥ 3 mm) occurred in 25% of varus and 54% of valgus knees and severe imbalances (≥ 5 mm) were present in up to 8% of varus and 19% of valgus knees. Higher flexion space imbalance rates were created with TEA versus PC (p < 0.001). Using TEA, only 49% of varus and 18% of valgus knees had < 3 mm of imbalance throughout the extension and flexion spaces, and medial and lateral compartments.

CONCLUSION

A systematic use of the simulated measured resection MA technique for TKA leads to many cases with imbalance. Some imbalances may not be correctable surgically and may result in TKA instability. Modified versions of the MA technique or other alignment methods that better reproduce knee anatomies should be explored.

LEVEL OF EVIDENCE

2.

Slight under-correction using individualized intentional varus femoral cutting leads to favorable outcomes in patients with lateral femoral bowing and varus knee

PURPOSE

Restoration of neutral alignment is considered key in total knee arthroplasty (TKA). However, this may be undesirable and can result in medial soft-tissue over-release in patients with varus knee and lateral femoral bowing. This study aimed to determine whether individualized intentional varus distal femoral cutting yielded satisfactory clinical and radiological outcomes.

METHODS

A total of 77 patients (91 knees) with varus knee (hip-knee-ankle axis ≥ 10°) and lateral femoral bowing > 5° underwent navigation-assisted primary TKA using individualized intentional varus distal femoral cutting. Knee Society scores, Western Ontario and McMaster Universities scores, and radiographs for limb alignment, implant alignment, and aseptic loosening were evaluated. Subgroup analyses were performed according to the limb alignment and coronal femoral component alignment (0° ± 3° vs. varus of > 3°).

RESULTS

All clinical outcomes significantly improved at the final follow-up (p < 0.05 in all). The mechanical axis angle changed from 13.1° ± 2.7° to 2.8° ± 1.5°. The coronal femoral component angle at the final follow-up was 2.8° ± 1.3°. Radiolucent lines were observed in 6 cases (6.6%) and were less than 2 mm in all cases without progression. In subgroup analyses, no significant differences were observed in clinical outcomes (n.s. in all) and in the incidence of radiolucent lines (n.s. in limb alignment, n.s. in coronal femoral component alignment).

CONCLUSIONS

Individualized intentional varus distal femoral cutting yielded favorable clinical outcomes without complications at 5-year follow-up. Slight under-correction using intentional varus distal femoral cutting could be a viable option in patients with varus knee and lateral femoral bowing during navigation-assisted TKA.

LEVEL OF EVIDENCE

IV.

Efficacy and Safety of Functional Medial Ligament Balancing With Stepwise Multiple Needle Puncturing in Varus Total Knee Arthroplasty

BACKGROUND

The aims of this study were to (1) describe our functional stepwise multiple needle puncturing (MNP) technique as the final step in medial ligament balancing during total knee arthroplasty (TKA) and (2) evaluate whether this technique can provide sufficient medial release with safety.

METHODS

A total of 137 patients with 212 consecutive knees who underwent TKAs with or without functional stepwise MNP of superficial medial collateral ligament was recruited in this prospective cohort. Eighty-one patients with 129 knees who performed serial stress radiographs were enrolled in the final assessment. Superficial medial collateral ligament was punctured selectively (anteriorly or posteriorly or both) and sequentially depending on the site and degree of tightness. Mediolateral stability was assessed using serial stress radiographs and comparison was performed between the MNP and the non-MNP groups at postoperative 6 months and 1 year. Clinical outcomes were also evaluated between 2 groups.

RESULTS

Fifty-five TKAs required additional stepwise MNP (anterior needling 19, posterior needling 3, both anterior and posterior needling 33). Preoperative hip-knee-ankle angle and the difference in varus-valgus stress angle showed significant difference between the MNP and the non-MNP groups, respectively (P = .009, P = .037). However, there was no significant difference when comparing the varus-valgus stress angle between the MNP and the non-MNP groups during serial assessment. Clinical outcomes including range of motion also showed no significant differences between the 2 groups.

CONCLUSION

Functional medial ligament balancing with stepwise MNP can provide sufficient medial release with safety in TKA with varus aligned knee without clinical deterioration or complication such as instability.

LEVEL OF EVIDENCE

Level II, Prospective cohort study.

Preoperative Varus-Valgus Stress Angle Difference Is Valuable for Predicting the Extent of Medial Release in Varus Deformity during Total Knee Arthroplasty

Purpose

The purpose of this study was to compare the predictive value of the valgus stress angle (SA), varus SA and varus-valgus SA difference (VVD) in predicting the degree of medial release in varus deformity during total knee arthroplasty (TKA).

Materials and Methods

One hundred eight TKAs (78 patients), which were performed in primary osteoarthritis with varus knee deformity, were retrospectively classified into three groups according to the degree of medial release (group A, mild release; group B, moderate release; and group C, severe release). Medical charts were reviewed, and long weight bearing standing anteroposterior radiographs and varus-valgus stress radiographs were evaluated.

Results

The valgus SA was significantly different between group A and B and between group A and C. However, it was not significantly different between group B and C. The varus SA was significantly different between group B and C and between group A and C. However, it was not significantly different between group A and B. The VVD was significantly different in all intergroup comparisons.

Conclusions

Evaluation of the VVD is more valuable in predicting the degree of medial release in TKA performed in varus knee deformity than evaluation of the simple valgus and varus SA.

Predictability of open superficial medial collateral ligament lengthening technique in total knee arthroplasty. Comparison of multiple needle puncturing and subperiosteal elevation: A cadaver study

PURPOSE

Lengthening of superficial medial collateral ligament (sMCL) is often needed in total knee replacement for varus osteoarthritis knee. This study aimed to compare the relationship of multiple needle puncturing (MNP) and subperiosteal elevation (SE) for sMCL lengthening on the gap increment and sequential lengthening in cadaveric knees.

HYPOTHESIS

MNP produces more reliable gap increment than SE technique for sMCL lengthening performed in knee flexion.

METHODS

From 8 pairs of cadaveric knees, one knee from each pair was randomly assigned to undergo MNP and the others to SE. In the MNP group, an 18gauge needle was used to puncture through the sMCL, performing five punctures each time of release. For the SE group, a periosteal elevator was used to sequentially deepen distally beneath the sMCL insertion with an increment depth of 5mm each time of release. The primary outcome was the medial gap increment at knee extension and 90° knee flexion after every attempt in each group.

RESULTS

At each level of lengthening, the widening of flexion and extension gap were not significantly different between the two techniques except for lengthening after 4 and 6 attempts of SE that gave greater widening in extension gap. Variability (width of mid 95% of values) was significantly greater for any given number of attempts using SE than MNP (0.5 vs. 0.24mm per attempt for extension and 2.28 vs. 0.95mm per attempt for flexion; both p<0.001).

CONCLUSION

The MNP technique is a reproducible technique for lengthening the sMCL in knee flexion. It has less variability in gap widening compared to the SE technique.

LEVEL OF EVIDENCE

II, controlled randomized laboratory study.

Step-wise medial collateral ligament needle puncturing in extension leads to a safe and predictable reduction in medial compartment pressure during TKA

PURPOSE

Medial soft tissue release in a varus deformity knee during total knee arthroplasty is essential for accurate balancing of the reconstruction. This study attempts to quantify the effect of sequential needle puncturing of the medial collateral ligament (MCL) using a pressure sensor insert (Verasense by OrthoSensor) and gap measurement under tension.

METHODS

Cruciate-retaining arthroplasties were placed in 14 cadaveric knees. The MCL was elongated by step-wise perforation, in five sets of five perforations, with the use of an 18-gauge needle, followed by valgus stress. Following the fifth set of needle perforations, blade perforation was performed on the remaining tense fibers of the MCL. Following each step-wise perforation, corresponding medial compartment pressures and gap measurements under tension were recorded.

RESULTS

Sensor measurements correlated closely with step-wise tissue release (R = 0.73, p < 0.0001), and a significant decrease in pressure was found in early needle puncturing (mean 49 N after 5, 83 N after 15, p values < 0.05), although changes diminished at later stages of needle perforation (90 N after 20). Gap measurement demonstrated small gradual changes with early puncturing, but showed significant opening in the later stages of release. There was minimal variation in pressure or gap measurements in flexion versus extension. This finding suggests that MCL needle puncture will not lead to unequal gaps between flexion and extension. There were no cases of MCL over-release after 15 punctures, one case after 20 punctures, and three after blade perforation.

CONCLUSION

Needle puncturing of the MCL in extension for up to 15 punctures can be a safe and predictable way to achieve medial opening when balancing a varus knee during TKA as demonstrated in this cadaveric model. Blade perforation should be used with caution to avoid over-release. The needle puncture method can be used by surgeons to achieve reliable reductions in medial compartment pressures, to help achieve a balanced TKA, with minimal risk of over-release.

Correcting Severe Varus Deformity Using Trial Components During Total Knee Arthroplasty

BACKGROUND

Extensive medial soft tissue release may be necessary to correct severe varus deformity during total knee arthroplasty (TKA). However, this procedure may result in instability. Here, we describe a novel soft tissue balancing technique, which can minimize medial release in severe varus deformity during TKA.

METHODS

Fifty knees (40 patients) with hip-knee-ankle angle of more than 20° of varus were corrected using this technique (group 1). After achieving flexion gap balancing by needle puncturing and spreading of the superficial medial collateral ligament, extension gap balancing was obtained by gradual extension with the trial components in place. After group 1 was set, a one-to-one patient-matched control group who had mild varus deformity was selected by propensity score matching (50 knees, 48 patients, group 2). At postoperative 1 year, mediolateral laxity was compared between the 2 groups using the stress radiographs. Clinical outcomes were also compared using the Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index score.

RESULTS

There were no differences in mean medial and lateral laxities between groups 1 and 2 at 1 year after the operation (medial laxity: 2.3° ± 1.4° and 2.7° ± 1.3°, respectively, P = .310) (lateral laxity: 3.6° ± 1.7° and 3.2° ± 2.0°, respectively, P = .459). There were no significant differences in postoperative clinical scores and knee alignment.

CONCLUSION

Our technique of obtaining extension gap balancing using trial components led to safe and effective balancing by avoiding unnecessary extensive release in severe varus deformity during TKA.

Are Midterm Patient-Reported Outcome Measures Between Rotating-Platform Mobile-Bearing Prosthesis and Medial-Pivot Prosthesis Different? A Minimum of 5-Year Follow-Up Study

BACKGROUND

Both rotating-platform (RP) mobile-bearing and medial-pivot (MP) fixed-bearing prostheses allow axial femorotibial rotation using a highly conforming polyethylene insert. However, limited comparative data are available between the 2 designs. This study was performed to compare the midterm clinical outcomes and patient-reported outcome measures (PROMs) of RP and MP prostheses.

METHODS

We retrospectively reviewed the records of 52 total knee arthroplasties using RP mobile-bearing prosthesis and 49 total knee arthroplasties using MP fixed prosthesis with a minimum follow-up period of 5 years. Clinical and radiological outcomes, failure rates, and PROMs, including the Western Ontario and McMaster Universities Osteoarthritis Index score and satisfaction, were compared.

RESULTS

There was no difference in clinical or radiographic outcomes (P > .1 for all comparisons), with the exception of the larger flexion contracture (FC) in the MP group (0.3° in RP vs 2.3° in MP, P < .01). No failure in either group was recorded during the study period. PROMs were comparable (P > .1 in all comparisons), with the exception of higher satisfactions in the RP group while performing light household duties (P < .01) and leisure or recreational activities (P = .014) in patients without FC.

CONCLUSION

The midterm clinical results with both the RP mobile-bearing and MP fixed-bearing prostheses were satisfactory. Although both prostheses provided comparable PROMs, patients with an RP prosthesis were more satisfied than those with an MP prosthesis for highly demanding activities that are strongly associated with the presence of postoperative FC.

Effect of Soft Tissue Releases on Joint Space Opening in Total Knee Arthroplasty

BACKGROUND

The purpose of this study was to determine the gap achieved to the medial and lateral compartments following sectioning and release of the relevant soft tissues in preparation for a total knee arthroplasty.

METHODS

A custom-designed knee tensioner allowed the application of forces to the medial and lateral compartments of 12 cadaveric knee specimens. Loads of 100 N and 200 N were applied to each compartment, and the resulting displacement was measured in the following conditions: (1) All soft tissues intact, (2) an arthrotomy, (3) anterior cruciate ligament (ACL) sectioned, (4) posterior cruciate ligament (PCL) sectioned, and (5) release of the anterior aspect of the deep medial collateral ligament (MCL) fibers. Tensions were applied for all conditions from 90° to 0° of knee flexion in 30° increments.

RESULTS

No differences were found in medial or lateral displacement after the arthrotomy or releasing the ACL or PCL at either 100 N or 200 N. At the 100 N load application, there was a significant increase in gap width when the anterior portion of the deep MCL was released (7.49 mm) compared to the intact (5.28 mm) and arthrotomy (5.75 mm) conditions. With respect to the 200 N load application, there were statistically significant differences detected between the deep MCL fiber release (11.09 mm) and intact conditions (8.05 mm) and release of the deep MCL and arthrotomy conditions (8.77 mm).

CONCLUSION

The medial parapetellar arthrotomy, ACL and PCL sectioning did not result in medial or lateral displacement changes. The release of the anterior fibers of the deep MCL as part of the surgical exposure increased the medial gap magnitude.

A Novel Medial Soft Tissue Release Method for Varus Deformity during Total Knee Arthroplasty: Femoral Origin Release of the Medial Collateral Ligament

Introduction

Numerous methods of medial soft tissue release for severe varus deformity during total knee arthroplasty (TKA) have been reported. These include tibial stripping of the superficial medial collateral ligament (MCL), pie-crusting technique, and medial epicondylar osteotomy. However, there are inherent disadvantages in these techniques. Authors hereby present a novel quantitative method: femoral origin release of the medial collateral ligament (FORM).

Surgical Technique

For medial tightness remaining even after the release of the deep MCL and semimembranosus, the FORM is initiated with identification of the femoral insertion area of the MCL with the knee in flexion. Starting from the most posterior part of the femoral insertion, one third of the MCL femoral insertion is released from its attachment. If necessary, further sequential medial release is performed.

Materials and Methods

Seventeen knees that underwent the FORM were evaluated for radiological and clinical outcomes.

Results

Regardless of the extent of the FORM, no knees showed residual valgus instability at 24 weeks after surgery.

Conclusions

As the FORM is performed in a stepwise manner, fine adjustment during medial release might be beneficial to prevent inadvertent over-release of the medial structures of the knee.