Dataset Information

What Factors Are Associated With Femoral Component Internal Rotation in TKA Using the Gap Balancing Technique?

ABSTRACT:

Background

When using the gap-balancing technique for TKA, excessive medial release and varus proximal tibial resection can be associated with internal rotation of the femoral component. Previous studies have evaluated the causes of femoral component rotational alignment with a separate factor analysis using unadjusted statistical methods, which might result in treatment effects being attributed to confounding variables.

Questions/purposes

(1) What pre- and intraoperative factors are associated with internal rotation of the femoral component in TKA using the gap balancing technique? (2) To what degree does femoral component rotation as defined by the navigation system differ from rotation as measured by postoperative CT?

Methods

Three hundred seventy-seven knees that underwent computer-assisted primary TKA attributable to degenerative osteoarthritis with varus or mild valgus alignment in which medial soft tissue release was performed, and those with preoperative radiographs including preoperative CT between October 2007 and June 2014 were included in the study. To achieve a balanced mediolateral gap, the structures released during each medial release step were as follows: Step 1, deep medial collateral ligament (MCL); Step 2, superficial MCL (proximal, above the pes anserine tendon) and semimembranosus tendon; and Step 3, the superficial MCL (distal, below the pes anserine tendon). Knees with internal rotation of the femoral component, which was directed by navigation, to achieve a rectangular mediolateral flexion gap were considered cases, and knees without internally rotated femoral components were considered controls. Univariable analysis of the variables (age, sex, BMI, operated side, preoperative hip-knee-ankle angle, preoperative medial proximal tibial angle, preoperative rotation degree of the clinical transepicondylar axis [TEA] relative to the posterior condylar axis [PCA], coronal angle of resected tibia, resection of the posterior cruciate ligament, type of prosthesis, and extent of medial release) of cases and controls was performed, followed by a multivariable logistic regression analysis on those factors where p equals 0.15 or less. For an evaluation of navigation error, 88 knees that underwent postoperative CT were analyzed. Postoperative CT scans were obtained for patients with unexplained pain or stiffness after the operations. Using the paired t-test and Pearson's correlation analysis, the postoperative TEA-PCA measured with postoperative CT was compared with theoretical TEA-PCA, which was calculated with preoperative TEA-PCA and actual femoral component rotation checked by the navigation system.

Results

After controlling for a relevant confounding variable such as postoperative hip-knee-ankle angle, we found that the extent of medial release (Step 1 as reference; Step 2: odds ratio [OR], 5.7, [95% CI, 2.2-15]; Step 3: OR, 22, [95% CI, 7.8-62], p < 0.001) was the only factor we identified that was associated with internal rotation of the femoral component. With the numbers available, we found no difference between the mean theoretical postoperative TEA-PCA and the postoperative TEA-PCA measured using postoperative CT (4.8° ± 2.7º versus 5.0° ± 2.3º; mean difference, 0.2° ± 1.5º; p = 0.160).

Conclusions

Extent of medial release was the only factor we identified that was associated with internal rotation of the femoral component in gap-balancing TKA. To avoid internal rotation of the femoral component, we recommend a carefully subdivided medial-releasing technique, especially for the superficial MCL because once the superficial MCL has been completely released it cannot easily be restored.

Level of evidence

Level III, therapeutic study.

SUBMITTER: Lee SY

PROVIDER: S-EPMC5498379 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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Publications

What Factors Are Associated With Femoral Component Internal Rotation in TKA Using the Gap Balancing Technique?

Lee Seung-Yup SY Lim Hong-Chul HC Jang Ki-Mo KM Bae Ji-Hoon JH

Clinical orthopaedics and related research 20170323 8

<h4>Background</h4>When using the gap-balancing technique for TKA, excessive medial release and varus proximal tibial resection can be associated with internal rotation of the femoral component. Previous studies have evaluated the causes of femoral component rotational alignment with a separate factor analysis using unadjusted statistical methods, which might result in treatment effects being attributed to confounding variables.<h4>Questions/purposes</h4>(1) What pre- and intraoperative factors ...[more]

PMID: 28337656

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Project description:Introduction:Recently, some studies showed assessment of the component gap is important for determination of the implant-inserted condition during total knee arthroplasty (TKA). We perform the modified gap technique with adjustment of the virtual gap which estimated by computer-aided design (CAD) using navigation system. The purpose of this study was to compare the virtual gap (CAD-gap) with the actual gap after inserting a femoral trial component (Trial-gap), and examine the usefulness of the surgical technique. Materials and methods:The subjects were 35 patients who underwent primary TKA using a navigation system and posterior-stabilized type TKA. The surgical procedure was to produce an extension gap, confirm the flexed CAD-gap on the navigation screen based on CAD data, and plan osteotomy of the femur. After osteotomy, the femoral component was inserted and the gap balance was measured. A tensor was used to adjust and measure the gap balance. Initial alignment, rotation of the femoral component, soft tissue balance in extension, final alignment after fixing all components, and the CAD- and Trial-gaps in both extension and flexion were evaluated. Results:The mean initial alignment angle, rotation angle of the femoral component, soft tissue balance angle and final alignment angle were 8.1 ± 4.2° varus, 3.5 ± 1.3°external rotation, 2.7 ± 2.5° varus and 0.4 ± 1.4° varus respectively. The mean medial and lateral CAD-gaps in extension were 10.8 ± 2.5 and 13.7 ± 2.5 mm, and the mean medial and lateral CAD-gaps in flexion were 12.2 ± 2.2 and 13.9 ± 2.7 mm. The equivalent Trial-gaps in extension and flexion were 10.5 ± 2.6 and 11.4 ± 3.1 mm, and 12.2 ± 2.5 and 14.4 ± 2.8 mm. The CAD- and Trial-gaps differed significantly only for lateral gaps in extension. Conclusion:In comparing the CAD-gap and the Trial-gap, only small difference was found in the lateral gap of extension. The other gaps in both extension and flexion were well maintained. We concluded adjustment of the CAD-gap during surgery using a navigation system can be used to adjust the actual component gap especially in the medial side.

Project description:BackgroundThis meta-analysis was designed to compare the accuracy of soft tissue balancing and femoral component rotation as well as change in joint line positions, between the measured resection and gap balancing techniques in primary total knee arthroplasty.MethodsStudies were included in the meta-analysis if they compared soft tissue balancing and/or radiologic outcomes in patients who underwent total knee arthroplasty with the gap balancing and measured resection techniques. Comparisons included differences in flexion/extension, medial/lateral flexion, and medial/lateral extension gaps (LEGs), femoral component rotation, and change in joint line positions. Finally, 8 studies identified via electronic (MEDLINE, EMBASE, and the Cochrane Library) and manual searches were included. All 8 studies showed a low risk of selection bias and provided detailed demographic data. There was some inherent heterogeneity due to uncontrolled bias, because all included studies were observational comparison studies.ResultsThe pooled mean difference in gap differences between the gap balancing and measured resection techniques did not differ significantly (-0.09 mm, 95% confidence interval [CI]: -0.40 to +0.21 mm; P = 0.55), except that the medial/LEG difference was 0.58 mm greater for measured resection than gap balancing (95% CI: -1.01 to -0.15 mm; P = 0.008). Conversely, the pooled mean difference in femoral component external rotation (0.77°, 95% CI: 0.18° to 1.35°; P = 0.01) and joint line change (1.17 mm, 95% CI: 0.82 to 1.52 mm; P < 0.001) were significantly greater for the gap balancing than the measured resection technique.ConclusionThe gap balancing and measured resection techniques showed similar soft tissue balancing, except for medial/LEG difference. However, the femoral component was more externally rotated and the joint line was more elevated with gap balancing than measured resection. These differences were minimal (around 1 mm or 1°) and therefore may have little effect on the biomechanics of the knee joint. This suggests that the gap balancing and measured resection techniques are not mutually exclusive.

Project description:BACKGROUND:Many factors contributing to anterior cruciate ligament (ACL) injury risk have been investigated. Recently, some ACL-injured individuals have presented with a decreased range of hip internal rotation compared with controls. The pathomechanics of why decreased hip range of motion increases risk of ACL injury have not yet been studied. HYPOTHESIS:Peak relative strain of the anteromedial bundle of the ACL (AM-ACL) during a simulated single-leg pivot landing is inversely related to the available range of internal femoral rotation. STUDY DESIGN:Controlled laboratory study. METHODS:A series of pivot landings were simulated in 10 female and 10 male human knee specimens with a testing apparatus that applied a 2-bodyweight impulsive load, inducing knee compression, flexion moment, and internal tibial torque. The range of internal femoral rotation was (1) locked at ~0°, (2) limited with a hard stop to ~7°, (3) limited with a hard stop to ~11°, or (4) free, with rotation resisted by 2 springs to simulate the resistance of the active hip rotator muscles to stretch. The AM-ACL strain was quantified with a differential variable reluctance transducer. A linear mixed model was used to determine whether a significant linear relation existed between peak AM-ACL relative strain and range of internal femoral rotation. RESULTS:Peak AM-ACL relative strain was inversely related to the available range of internal femoral rotation (R (2) = 0.91; P < .001), with strain increasing 1.3% for every 10° decrease in rotation; this represented a 20% increase in peak relative strain, given an average range of femoral rotation of 15° upon landing in healthy athletes. CONCLUSION:Peak AM-ACL relative strain was inversely proportional to the available range of internal femoral rotation during simulated single-leg pivot landings. CLINICAL RELEVANCE:Decreased range of internal femoral rotation results in greater ACL strain and may therefore increase the susceptibility to ACL rupture with athletic cutting and pivoting activities. Screening for a limited range of hip internal rotation should therefore become a component of not only ACL injury prevention programs but also evaluation protocols for those with ACL injuries and/or reconstructions.

Project description:OBJECTIVE:Total knee arthroplasty (TKA) is one of the most universal and effective means for treating terminal stage osteoarthritis (OA) of knee. Accurate intramedullary guide of femur is the basis for the distal femoral cuts. Determining the surgical transepicondylar axis (sTEA) is the key to reconstruction of the femoral rotational alignment, because the correct rotational alignment can place the femoral component in the right position, balance the flexion gap so that the inner and outer tension is equal, get stability during the flexion process of the knee, and enhance the quality of life of patients. With the development of three-dimensional printing (3DP) technology in the medical domain, the application of patient-specific instrumentation (PSI) in arthroplasty has become more common. The aim of this study was to evaluate the accuracy of a novel 3D-printed patient-specific intramedullary guide to control femoral component rotation in TKA. METHODS:Eighty patients (65 females and 15 males) with knee OA were included in this prospective randomized study. The patients were divided into two groups by random number table method, 40 in each group. TKA assisted by PSI (PSI group) and conventional TKA (conventional group) was performed respectively. Clinical outcomes [operation time, postoperative drainage volume, duration of drainage, Hospital for Special Surgery knee score (HSS), American Knee Society knee score (AKS)] and radiological outcomes [hip-knee-ankle angle (HKA), posterior condylar angle (PCA), patella transverse axis-femoral transepicondylar axis angle (PFA), depth of intramedullary guide] were compared between and within the two groups. RESULTS:PSI group had less postoperative drainage volume but longer operation time than the conventional group (P < 0.05). The AKS and HSS scores after surgery were improved compared with those before surgery in each group (P < 0.05). However, there was no significant difference in the duration of drainage and range of motion (ROM) after surgery between the two groups. For the radiological results, the HKA and PFA were improved after surgery in both groups (P < 0.05).The postoperative PFA and PCA of the PSI group were closer to 0°, which was better than that of the conventional group (P < 0.05). The depth of intramedullary guide in the PSI group was less than the conventional group (P < 0.05). But there was no significant difference in HKA before and after surgery between the two groups as well as the preoperative PFA. CONCLUSION:The short-term clinical efficacy of TKA assisted by PSI was similar to the conventional TKA. Although TKA assisted by PSI spent more time during operation, it could assist in intramedullary guide and align femoral rotation more accurately.

Dataset Information

What Factors Are Associated With Femoral Component Internal Rotation in TKA Using the Gap Balancing Technique?

Background

Questions/purposes

Methods

Results

Conclusions

Level of evidence

Publications

What Factors Are Associated With Femoral Component Internal Rotation in TKA Using the Gap Balancing Technique?

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