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Technical feasibility of personalized articulating knee joint distraction for treatment of tibiofemoral osteoarthritis
Abstracts / Osteoarthritis and Cartilage 24 (2016) S63eS534
from the X-Rays after TKA surgeries with different surgical instruments, and specifically focused on the differences between the anterior tibial cutting guide and medial tibial cutting guide. Methods: We retrospectively reviewed 169 patients with 191 primary TKA surgeries performed by the same surgeon from 2011 to 2015. There were 39 male and 130 female. The pre-operative and post-operative lower limb mechanical axis, femoral and tibial component position in the coronary and sagittal planes were measured from the X-rays. Based on the different tibial cutting guides used during surgery, we classified the patients as 2 groups: 137 TKAs with anterior tibial cutting guide and 54 with medial tibial cutting guide. Students’ t-test was used for statistical analysis for all the numeric variables and chi-square tests for categorical variables. Results: The mean age of the patients was 69.3 ± 7.9 years. The mean surgical time was 65.0 ± 14.0 minutes. For the medial tibia cutting guide group, the post-operative lower limb mechanical axis and tibial component position showed valgus deformity in the coronary plane with degrees of 1.4 ± 3.7 and 0.6 ± 2.1, respectively. For the anterior tibia cutting guide group, the post-operative lower limb mechanical axis and tibial component position showed varus deformity with degrees of 0.06 ± 3.5 and 0.2 ± 2.1, respectively. The differences between the 2 groups were significant, with the p value of 0.012 and 0.021, respectively. If we defined varus or valgus degree of over 3 as abnormal, the incidence of tibial component malposition was 6.7% and femoral component malposition was 8.7%. The incidence of lower limb axis deviation was 28.5% (with 15.6% valgus and 12.8% varus). There were no significant differences between the 2 groups. Conclusions: Literatures have shown that the higher varus degree after TKA surgery, the higher incidence of component aseptic loosening. This study showed that the use of medial tibial cutting guide can decrease the chances of cutting tibia bone in a varus position. (The post-operative mechanical axis and component position both showed a mild valgus deformity). However, the difference to the anterior tibial cutting guide was relatively small and thus may not be of great significance to the clinical work. 892 KNEE BIOMECHANICS ARE FURTHER FROM NORMAL IN MALE THAN IN FEMALES FOLLOWING TOTAL KNEE ARTHROPLASTY J.A. McClelland y, J.A. Feller z, K.E. Webster y. y La Trobe Univ., Bundoora, Australia; z OrthoSport Victoria, Melbourne, Australia Purpose: Total knee arthroplasty (TKA) consistently improves pain and quality of life for people with disabling knee osteoarthritis. However, there are wide discrepancies in the reported outcomes for patients. In order to provide clearer expectations for patients, there is a need to investigate whether patients with particular characteristics may expect specific outcomes following surgery. Pre-operative evaluations of function, and specifically knee biomechanics of walking, suggest that a person’s gender may play a role in determining their outcome from TKA surgery. Whilst there is limited information that suggests females may expect poorer long-term functional outcome, the effect of gender on knee biomechanics in patients with TKA has not been evaluated. We hypothesise that males with TKA will walk with knee biomechanics that are closer to that of unimpaired males than females with TKA compared to unimpaired females. Methods: There were 126 participants: 86 participants were 12 months post TKA surgery and 40 control participants were matched to age (±2 years) and gender of TKA participants. A 10 camera Vicon motion analysis system was used to collect video data from 24 retroreflective markers placed at specific anatomical landmarks as participants walked at selfselected speed. Two embedded force platforms recorded ground reaction force data. Spatiotemporal parameters, peak knee flexion angle during stance phase, peak knee flexion angle during swing phase, peak knee flexion moment and peak knee adduction moment were recorded from five trials of level walking for each participant and combined to form group averages. Walking speed was compared between all four groups (male TKA, n ¼ 41; male control, n ¼ 18; female TKA, n ¼ 44; and female control, n ¼ 21) using a univariate analysis of variance. Peak knee biomechanics were compared between groups using the same analysis except that body mass index and walking speed were included as covariates. Post hoc analysis (Bonferroni) was performed for significant findings by comparing the male TKA group to the male control group, and the female TKA group to the female control group. The size of the difference between these groups was estimated by calculating Cohen’s d effect sizes (ES). Results: There was a significant difference between the groups for all variables of interest. Post hoc analysis showed that there was a large
S517
difference between male TKA and male control participants for the knee flexion angle (ES ¼ 1.1), knee flexion moment (ES ¼ 0.9), and knee adduction moment (ES ¼ 1.5) during walking. In contrast, only the knee adduction moment was significantly different for the female TKA compared to the female control participants (ES ¼ 0.9). Conclusions: Contrary to our hypothesis, knee biomechanics in males with TKA appear to be further from normal than for females. Unimpaired males walk with greater knee flexion angles and moments than females, and therefore males with TKA may need to use more extreme degrees of flexion to be close to normal than females. These findings underpin the importance of developing interventions that aim to restore normal knee flexion during gait for people with TKA, which may be particularly pertinent for male patients. 893 TECHNICAL FEASIBILITY OF PERSONALIZED ARTICULATING KNEE JOINT DISTRACTION FOR TREATMENT OF TIBIOFEMORAL OSTEOARTHRITIS T. Struik, J.E. Jaspers, N.J. Besselink, P.M. van Roermund, S.C. Mastbergen, F.P. Lafeber. Univ. Med. Ctr. Utrecht, Utrecht, Netherlands Purpose: Knee osteoarthritis is a highly prevalent degenerative joint disorder characterized by joint tissue damage and pain. Knee Joint Distraction (KJD) has been introduced as a joint preserving surgical procedure to postpone replacement of the joint by total knee prosthesis. A frequently used standard external standard external device for distraction (Figure 1a) poses burden to patients due to the absence of joint flexion for the duration of the treatment of at least 6 weeks. Therefore a personalized articulating KJD-device was developed and evaluated. Methods: Based on a frequently applied rigid KJD-device, using equal bone pin positions and connectors for fixation, an articulating distraction device was developed that uses a cam-following system to adapt to the complex knee kinematics in the sagittal plane (Figure 1b). In support, a device was developed for capturing the patient-specific sagittal joint articulation with use of an additional alignment tool (Figure 1c). The obtained kinematic data were translated by custom made software into joint-specific cams that were subsequently manufactured and inserted in the KJD-device, as such providing personalized knee motion (Figure 1d). Distraction of 5 mm was performed similar to rigid distraction, incorporating 3 mm resilience at 400 N axial load for each joint side. A range-of-motion (ROM) of 30 deg flexion was aimed for. Pre-clinical evaluation of the working principle was performed on human cadaveric legs (n ¼ 3) and system stiffness characteristics were evaluated in a biomechanical test-setup. Results: The developed device was found to be technically feasible. Patient-specific parts could be produced and assembled (representative shape shown in Figure 1d). The desired ROM of 30 deg was obtained for all specimen and no irregularities (crepitus) in the motion as dictated by the system were experienced. Total system stiffness showed to be similar to the rigid joint distraction setup within the evaluated ROM (109.6 N/mm at 0 deg flexion and 116.8 N/mm at 30 deg flexion for the articulating distraction device and 120.6 N/mm for the rigid distraction device). Moreover, the patient-specific approach demonstrated compliance for deviations from anatomical and alignment origin during initial placement of the KJD-device. Conclusions: Articulation during KJD has potential to reduce the burden of distraction therapy and the proposed method was concluded to be technically feasible. This can add to accepting this treatment and the next step would be testing clinical feasibility of articulating KJD.
Figure 1. Rigid knee joint distraction device as applied in clinical practice (A). Sagittal view of the newly developed articulating distraction device (B). Joint specific kinematics was bilaterally obtained with a modular measurement device while parallelism of the hinges was ensured by an alignment tool (C). Kinematic data was processed into cam shapes for computer controlled manufacturing of joint specific parts (D).
from the X-Rays after TKA surgeries with different surgical instruments, and specifically focused on the differences between the anterior tibial cutting guide and medial tibial cutting guide. Methods: We retrospectively reviewed 169 patients with 191 primary TKA surgeries performed by the same surgeon from 2011 to 2015. There were 39 male and 130 female. The pre-operative and post-operative lower limb mechanical axis, femoral and tibial component position in the coronary and sagittal planes were measured from the X-rays. Based on the different tibial cutting guides used during surgery, we classified the patients as 2 groups: 137 TKAs with anterior tibial cutting guide and 54 with medial tibial cutting guide. Students’ t-test was used for statistical analysis for all the numeric variables and chi-square tests for categorical variables. Results: The mean age of the patients was 69.3 ± 7.9 years. The mean surgical time was 65.0 ± 14.0 minutes. For the medial tibia cutting guide group, the post-operative lower limb mechanical axis and tibial component position showed valgus deformity in the coronary plane with degrees of 1.4 ± 3.7 and 0.6 ± 2.1, respectively. For the anterior tibia cutting guide group, the post-operative lower limb mechanical axis and tibial component position showed varus deformity with degrees of 0.06 ± 3.5 and 0.2 ± 2.1, respectively. The differences between the 2 groups were significant, with the p value of 0.012 and 0.021, respectively. If we defined varus or valgus degree of over 3 as abnormal, the incidence of tibial component malposition was 6.7% and femoral component malposition was 8.7%. The incidence of lower limb axis deviation was 28.5% (with 15.6% valgus and 12.8% varus). There were no significant differences between the 2 groups. Conclusions: Literatures have shown that the higher varus degree after TKA surgery, the higher incidence of component aseptic loosening. This study showed that the use of medial tibial cutting guide can decrease the chances of cutting tibia bone in a varus position. (The post-operative mechanical axis and component position both showed a mild valgus deformity). However, the difference to the anterior tibial cutting guide was relatively small and thus may not be of great significance to the clinical work. 892 KNEE BIOMECHANICS ARE FURTHER FROM NORMAL IN MALE THAN IN FEMALES FOLLOWING TOTAL KNEE ARTHROPLASTY J.A. McClelland y, J.A. Feller z, K.E. Webster y. y La Trobe Univ., Bundoora, Australia; z OrthoSport Victoria, Melbourne, Australia Purpose: Total knee arthroplasty (TKA) consistently improves pain and quality of life for people with disabling knee osteoarthritis. However, there are wide discrepancies in the reported outcomes for patients. In order to provide clearer expectations for patients, there is a need to investigate whether patients with particular characteristics may expect specific outcomes following surgery. Pre-operative evaluations of function, and specifically knee biomechanics of walking, suggest that a person’s gender may play a role in determining their outcome from TKA surgery. Whilst there is limited information that suggests females may expect poorer long-term functional outcome, the effect of gender on knee biomechanics in patients with TKA has not been evaluated. We hypothesise that males with TKA will walk with knee biomechanics that are closer to that of unimpaired males than females with TKA compared to unimpaired females. Methods: There were 126 participants: 86 participants were 12 months post TKA surgery and 40 control participants were matched to age (±2 years) and gender of TKA participants. A 10 camera Vicon motion analysis system was used to collect video data from 24 retroreflective markers placed at specific anatomical landmarks as participants walked at selfselected speed. Two embedded force platforms recorded ground reaction force data. Spatiotemporal parameters, peak knee flexion angle during stance phase, peak knee flexion angle during swing phase, peak knee flexion moment and peak knee adduction moment were recorded from five trials of level walking for each participant and combined to form group averages. Walking speed was compared between all four groups (male TKA, n ¼ 41; male control, n ¼ 18; female TKA, n ¼ 44; and female control, n ¼ 21) using a univariate analysis of variance. Peak knee biomechanics were compared between groups using the same analysis except that body mass index and walking speed were included as covariates. Post hoc analysis (Bonferroni) was performed for significant findings by comparing the male TKA group to the male control group, and the female TKA group to the female control group. The size of the difference between these groups was estimated by calculating Cohen’s d effect sizes (ES). Results: There was a significant difference between the groups for all variables of interest. Post hoc analysis showed that there was a large
S517
difference between male TKA and male control participants for the knee flexion angle (ES ¼ 1.1), knee flexion moment (ES ¼ 0.9), and knee adduction moment (ES ¼ 1.5) during walking. In contrast, only the knee adduction moment was significantly different for the female TKA compared to the female control participants (ES ¼ 0.9). Conclusions: Contrary to our hypothesis, knee biomechanics in males with TKA appear to be further from normal than for females. Unimpaired males walk with greater knee flexion angles and moments than females, and therefore males with TKA may need to use more extreme degrees of flexion to be close to normal than females. These findings underpin the importance of developing interventions that aim to restore normal knee flexion during gait for people with TKA, which may be particularly pertinent for male patients. 893 TECHNICAL FEASIBILITY OF PERSONALIZED ARTICULATING KNEE JOINT DISTRACTION FOR TREATMENT OF TIBIOFEMORAL OSTEOARTHRITIS T. Struik, J.E. Jaspers, N.J. Besselink, P.M. van Roermund, S.C. Mastbergen, F.P. Lafeber. Univ. Med. Ctr. Utrecht, Utrecht, Netherlands Purpose: Knee osteoarthritis is a highly prevalent degenerative joint disorder characterized by joint tissue damage and pain. Knee Joint Distraction (KJD) has been introduced as a joint preserving surgical procedure to postpone replacement of the joint by total knee prosthesis. A frequently used standard external standard external device for distraction (Figure 1a) poses burden to patients due to the absence of joint flexion for the duration of the treatment of at least 6 weeks. Therefore a personalized articulating KJD-device was developed and evaluated. Methods: Based on a frequently applied rigid KJD-device, using equal bone pin positions and connectors for fixation, an articulating distraction device was developed that uses a cam-following system to adapt to the complex knee kinematics in the sagittal plane (Figure 1b). In support, a device was developed for capturing the patient-specific sagittal joint articulation with use of an additional alignment tool (Figure 1c). The obtained kinematic data were translated by custom made software into joint-specific cams that were subsequently manufactured and inserted in the KJD-device, as such providing personalized knee motion (Figure 1d). Distraction of 5 mm was performed similar to rigid distraction, incorporating 3 mm resilience at 400 N axial load for each joint side. A range-of-motion (ROM) of 30 deg flexion was aimed for. Pre-clinical evaluation of the working principle was performed on human cadaveric legs (n ¼ 3) and system stiffness characteristics were evaluated in a biomechanical test-setup. Results: The developed device was found to be technically feasible. Patient-specific parts could be produced and assembled (representative shape shown in Figure 1d). The desired ROM of 30 deg was obtained for all specimen and no irregularities (crepitus) in the motion as dictated by the system were experienced. Total system stiffness showed to be similar to the rigid joint distraction setup within the evaluated ROM (109.6 N/mm at 0 deg flexion and 116.8 N/mm at 30 deg flexion for the articulating distraction device and 120.6 N/mm for the rigid distraction device). Moreover, the patient-specific approach demonstrated compliance for deviations from anatomical and alignment origin during initial placement of the KJD-device. Conclusions: Articulation during KJD has potential to reduce the burden of distraction therapy and the proposed method was concluded to be technically feasible. This can add to accepting this treatment and the next step would be testing clinical feasibility of articulating KJD.
Figure 1. Rigid knee joint distraction device as applied in clinical practice (A). Sagittal view of the newly developed articulating distraction device (B). Joint specific kinematics was bilaterally obtained with a modular measurement device while parallelism of the hinges was ensured by an alignment tool (C). Kinematic data was processed into cam shapes for computer controlled manufacturing of joint specific parts (D).