Search

Purpose: Ligament balancing is a prerequisite for good function and survival in total knee arthroplasty (TKA). Various balancing techniques exist, but none have shown superior results. The pie-crusting technique by Bellemans of the medial collateral ligament is commonly utilized; however, it can be difficult to achieve repeatable ligament lengthening with this technique. Therefore, we invented a novel instrument to standardize the pie-crusting technique of the superficial and deep medial collateral ligament (hereafter MCL). The purpose was to examine if pie-crusting with the instrument could produce repeatable ligament lengthening. Methods: The MCL was isolated in 16 human cadaveric knees, and subjected to axial tension. The instrument was composed of a specific grid of holes in rows, used to guide sequential pie-crusting puncturing of the MCL with a Ø1.6 mm end-cutting cannula. Ligament lengthening was measured after each row of punctures. Regression analysis was performed on the results. Results: Mean lengthening ± SD in human cadaveric MCL for puncturing of row 1 in the instrument was 0.06 ± 0.09 mm, 0.06 ± 0.04 mm for row 2, 0.09 ± 0.08 mm for row 3, 0.06 ± 0.05 mm for row 4 and 0.06 ± 0.04 mm for row 5, giving a mean total lengthening of 0.33 ± 0.20 mm. Linear regression revealed that MCLs were repeatably lengthened by 0.07 mm per row when punctured using the instrument. Conclusions: MCLs showed linear lengthening in human cadavers for subsequent use of the instrument. Our instrument shows promising results for repeatable ligament lengthening. [ABSTRACT FROM AUTHOR]

Background and purpose -- Accurate measuring tools are essential in preoperative planning and for the study of the association between postoperative alignment and clinical outcome in total knee arthroplasty (TKA). We aimed to describe a simple method to measure preoperative hip-knee-femoral shaft (HKFS) angle and postoperative coronal alignment in TKA with the use of standard 3D CT and to compare preoperative HKFS angles and postoperative coronal alignment measured with the 3D CT technique and with standing long-leg hip-knee-ankle (HKA) radiographs. Patients and methods -- HKA radiographs and 3D CT were taken preoperatively and 3 months after the operation in 121 knees. The interrater reliability for the 3D CT method was calculated with intra-class correlation coefficient (ICC). The preoperative HKFS angles and the postoperative deformity measured with the 2 methods were compared and illustrated on Bland-Altman plots, frequency tables, and by Cohen's kappa coefficients (κ). Results -- The 3D CT method was feasible in all knees and the ICC was excellent. Mean (SD, range) difference in HKFS angle measured on HKA radiographs and on 3D CT was -0.3° (0.9°, -4.1° to 2.4°). Mean (SD, range) difference in postoperative deformity was 0.1° (1.6°, -5° to 6°). The 95% limits of agreement were 1.4° and -2° for HKFS and ±3° for postoperative alignment. The agreement in outlier (≥ 3°) identification was moderate with a κ (95% confidence interval) of 0.48 (0.32-0.64). Conclusion -- 3-dimensional computer tomography was feasible and was shown to be more accurate than traditional long-leg radiographs [ABSTRACT FROM AUTHOR]

Background and purpose — In the classical mechanical alignment technique, ligament balancing is considered a prerequisite for good function and endurance in total knee arthroplasty (TKA). However, it has been argued that ligament balancing may have a negative effect on knee function, and some authors advocate anatomic or kinematic alignment in order to reduce the extent of ligament releases. The effect of the trauma induced by ligament balancing on functional outcome is unknown; therefore, the aim of this study was to investigate this effect. Patients and methods — 129 knees (73 women) were investigated. Mean age was 69 years (42-82), and mean BMI was 29 (20-43). Preoperatively 103 knees had a varus deformity, 21 knees had valgus deformity, and 5 knees were neutral. The primary outcome measure was the Knee injury and Osteoarthritis Outcome Score (KOOS). Secondary outcome measures were the Oxford Knee Score (OKS) and patient satisfaction (VAS). All ligament releases were registered intraoperatively and outcome at 3 years’ follow-up in knees with and without ligament balancing was compared Results — 86 knees were ligament balanced and 43 knees were not. Ligament-balanced varus knees had more preoperative deformity than varus knees without ligament balancing (p = 0.01). There were no statistically significant differences in outcomes between ligament-balanced and non-ligament-balanced knees at 3 years’ follow-up. No correlation was found between increasing numbers of soft tissue structures released and outcome. Interpretation — We did not find any negative effect of the trauma induced by ligament balancing on knee function after 3 years. [ABSTRACT FROM AUTHOR]

Background and purpose -- There are many techniques for placing the femoral component in correct rotational alignment in total knee arthroplasty (TKA), but only a few have been tested against the supposed gold standard, rotation determined by postoperative computed tomography (CT). We evaluated the accuracy and variability of a new method, the clinical rotational axis (CRA) method, and assessed the association between the CRA and knee function. Patients and methods -- The CRA is a line derived from clinical judgement of information from the surgical transepicondylar axis, the anteroposterior axis, and the posterior condylar line. The CRA was used to guide the rotational positioning of the femoral component in 80 knees (46 female). At 3 years follow-up, the rotation of the femoral component was compared with the CT-derived surgical transepicondylar axis (CTsTEA) by 3 observers. Functional outcome was assessed with the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Oxford Knee Score (OKS) and patient satisfaction (VAS). Results -- The mean (95% CI) rotational deviation of the femoral component from the CTsTEA was 0.2° (-0.15°-0.55°). The standard deviation (95% CI) was 1.58° (1.36°-1.85°) and the range was from 3.7° internal rotation to 3.7° external rotation. No statistically significant association was found between femoral component rotation and KOOS, OKS, or VAS. Interpretation -- The CRA method was found to be accurate with a low grade of variability. [ABSTRACT FROM AUTHOR]

Purpose: The effect of patellar eversion on ligament laxity measurements is still unclear. The purpose of this study was to investigate the influence of patellar eversion on medial and lateral ligament laxity measurements performed intra-operatively in total knee arthroplasty (TKA).Methods: A total of 49 knees (27 female) with mean age 70 years (42-83) and mean body mass index of 28.5 were operated consecutively with a cruciate-retaining prosthesis. Medial and lateral ligament laxity in extension and in 90° of flexion was measured with the spatula-method intra-operatively after implantation of the prosthetic components with the patella everted and thereafter with the patella repositioned. The corresponding changes in gap height and inclination were calculated.Results: A statistically significant increase of 0.6 mm (p < 0.001) in ligament laxity (condylar lift-off) laterally in flexion was found with the patella repositioned compared to everted. No differences were found in extension or medially in flexion. Correspondingly, the flexion gap increased by 0.4 mm (p < 0.001) and the flexion gap inclination increased by 0.6° (p = 0.002) when the patella was repositioned.Conclusions: Earlier research has shown that ligament laxity must be at least 1-2 mm to cause inferior function after TKA. In the current study, we found that the effect of patellar eversion on ligament laxity measurements is too small to be considered clinically relevant. PROSPECTIVE STUDY EVALUATING THE EFFECT OF PATIENT CHARACTERISTICS: Level II. [ABSTRACT FROM AUTHOR]

Background and purpose — Recent research on outcomes after total knee arthroplasty (TKA) has raised the question of the ability of traditional outcome measures to distinguish between treatments. We compared functional outcomes in patients undergoing TKA with and without patellar resurfacing, using the knee injury and osteoarthritis outcome score (KOOS) as the primary outcome and 3 traditional outcome measures as secondary outcomes. Patients and methods — 129 knees in 115 patients (mean age 70 (42–82) years; 67 female) were evaluated in this single-center, randomized, double-blind study. Data were recorded preoperatively, at 1 year, and at 3 years, and were assessed using repeated-measures mixed models. Results — The mean subscores for the KOOS after surgery were statistically significantly in favor of patellar resurfacing: sport/recreation, knee-related quality of life, pain, and symptoms. No statistically significant differences between the groups were observed with the Knee Society clinical rating system, with the Oxford knee score, and with visual analog scale (VAS) for patient satisfaction. Interpretation — In the present study, the KOOS—but no other outcome measure used—indicated that patellar resurfacing may be beneficial in TKA. [ABSTRACT FROM PUBLISHER]

Background: Ligament balancing is considered a prerequisite for good function and survival in total knee arthroplasty (TKA). However, there is no consensus on how to measure ligament balance intra-operatively and the degree of stability obtained after different balancing techniques is not clarified. Purpose: This study presents a new method to measure ligament balancing in TKA and reports on the results of a try-out of this method and its inter-observer reliability. Methods: After the implantation of the prosthesis, spatulas of different thickness were used to measure medial and lateral condylar lift-off in flexion and extension in 70 ligament-balanced knees and in 30 knees were ligament balancing was considered unnecessary. Inter-observer reliability for the new method was estimated and the degree of medial-lateral symmetry in extension and in flexion, and the equality of the extension gaps and flexion gaps were calculated. Results: The method was feasible in all operated knees, and found to be very reliable (intraclass correlation coefficient = 0.88). We found no statistically significant difference in condylar lift-off between the ligament-balanced and the non ligament-balanced group, however, there was a tendency to more outliers in flexion in the ligament-balanced group. Conclusions: Our method for measuring ligament balance is reliable and provides valuable information in assessing laxity intra-operatively. This method may be a useful tool in further research on the relationship between ligament balance, function and survival of TKA. [ABSTRACT FROM AUTHOR]