Knee Surg Sports Traumatol Arthrosc DOI 10.1007/s00167-014-3321-x
KNEE
The effect of tibial rotation on knee medial and lateral compartment contact pressure Hamidreza Yazdi · Mohammadreza Mallakzadeh · Sara Sadat Farshidfar · Behrooz Givehchian · Hamidreza Daneshparvar · Hannes Behensky
Received: 17 August 2013 / Accepted: 10 September 2014 © European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2014
Abstract Purpose The progression of knee osteoarthritis (OA) is determined in part by mechanical effects on local structures. The mechanical influences of limb malalignment on cartilage loss are well known; however, the effect of rotational deformities on knee OA is not yet known. The aim of the current study was to evaluate the effect of tibial rotation on knee medial and lateral compartment contact pressure. Methods The left knees of six fresh whole-body cadavers were used in this study. Fujifilm Prescale super-low type film was used for contact pressure measurement. The films were inserted into the joint after arthrotomy. The cadavers were stabilized with a custom-made device, and axial force of half body weight specific to each cadaver was applied to the plantar surface of the feet. The examination was repeated after osteotomy of the fibula and tibia,
and the tibia was then rotated 15° or 30° internally (IR) or externally (ER) and securely fixed. The resulting films were scanned, and CP was determined using appropriate software. Results The p values for increased medial compartment contact pressure at 15° and 30° IR and 30° ER were 0.016, 0.025, and 0.025, respectively. For decreased medial compartment contact pressure at 15° ER, the p value was 0.020. The p values for increased lateral compartment contact pressure at 15° and 30° ER were 0.010 and 0.030, respectively. In this compartment, contact pressure changes at 15° and 30° IR were not significant. Conclusion This experimental study demonstrated that 15° IR of the tibial shaft increased contact pressure and 15° ER decreased contact pressure over the knee medial compartment. Keywords Knee · Contact pressure · Tibial rotation · Osteoarthritis
H. Yazdi (*) Department of Knee Surgery, Firoozgar Hospital, School of Medicine, Iran University of Medical Science, Tehran, Iran e-mail: [email protected] M. Mallakzadeh · S. Sadat Farshidfar Biomechanics Department, School of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran B. Givehchian Shafa Rehabilitation Hospital, School of Medicine, Iran University of Medical Science, Tehran, Iran H. Daneshparvar Legal Medicine Research Center, Legal Medicine Organization, Tehran, Iran H. Behensky Department of Orthopedic Surgery, Medical University Innsbruck, Innsbruck, Austria
Introduction Osteoarthritis (OA) of the knee accounts for a large percentage of disabilities of the lower extremities [10]. Poor understanding of the development of OA has led to the slow development of intervention that can modify the course of the disease [21]. To optimize the management of OA, it is important to increase the understanding of the predictors of its progression. If specific prognostic factors can be modified, it may be possible to decrease the progression of OA. Even if these prognostic factors cannot be modified, they can still be used to identify high-risk groups to allow modification of patient information and perspectives for medical treatment [4, 17].
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Knee Surg Sports Traumatol Arthrosc
The progression of knee OA is determined in part by mechanical effects on local structures. One mechanical influence on cartilage loss is limb alignment [9, 14]. Several studies have examined the relationship between frontal plane malalignment and the progression of knee OA [6, 7, 14, 15, 19, 21, 22]. The relationship between lower limb torsion and knee pathology has been previously investigated [1, 8, 16, 23, 25], but no study has focused solely on the quantitative effect of tibial torsion on tibiofemoral contact pressure. One of the best methods to evaluate the effect of biomechanical factors on the progression of knee OA is to measure direct loading on a specific site on the knee. Measurements taken under dynamic loading should be used to assess the biomechanical function of the knee [19]. The current study evaluated the effect of tibial torsion on tibiofemoral contact pressure over the knee medial and lateral compartments. In contrast to previous studies, the effect of hip rotation and foot progression angle was deleted in this study.
Materials and methods Based on a power analysis (power ratio 0.80) the left knee of the six fresh whole-body cadavers with the mean age of 32.5 ± 8 years (range 20–45 years), mean height of 175.3 ± 10.1 cm (range 157–183 cm), and mean body mass of 68.3 ± 16.3 kg (range 40–85 kg), was used in this study. All cadavers were examined clinically and radiographically and were determined to have no tibial malrotation or coronal and sagittal deformities. Prescale pressure-sensitive super-low type film (Fujifilm, Japan, 2011) was used to measure contact pressure. The film was cut into the shape of the medial and lateral compartments of the knee and sealed between two 0.05-mm-thick polyethylene sheets to prevent damage from joint fluid. After a midline incision and medial and lateral parapatellar knee arthrotomy, the articular surfaces, ligaments, and menisci of all knees were evaluated and determined to be intact with no signs of recent trauma. The method recommended by Kenawey et al. [16] was used to perform a medial and lateral total meniscectomy to facilitate insertion of pressure film into the medial and lateral compartments of the joints. Weight bearing was simulated using a novel device that allows a defined axial force to be applied to the left lower limb of supine whole-body cadavers. The device was fixed to the body using pelvic and thigh straps. Fibulectomy was performed between the proximal 2/3 and distal 1/3 of the fibula to harvest 2 cm of bone to facilitate tibial rotation. After implanting the film, the knee
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Fig. 1 Tibia rotated 15° externally and fixed with plate. Pressure films inserted into the medial and lateral compartment
Fig. 2 Red-colored Fujifilm obtained from the second sample
was fixed in full extension and the ankle was maintained in a neutral position. An axial force equivalent to half the body weight [16] specific to each specimen was constantly applied to the plantar surface of the foot for 2 min (protocol recommended by Fuji). The film was then removed. The tibial shaft was then exposed anteromedially, 2 parallel pins were inserted perpendicularly 2 cm apart into the mid-diaphysis of the tibia as reference points, and the tibia
Knee Surg Sports Traumatol Arthrosc Table 1 Descriptive statistics of medial and lateral compartments’ contact pressures before and after tibial torsion Minimum
Maximum
Mean
SD
Variance
Medial 0° Medial 15° IR Medial 30° IR Medial 15° ER
0.2 0.3 0.2 0.2
0.5 0.7 0.6 0.5
0.40 0.51 0.46 0.39
0.13 0.12 0.11 0.12
0.01 0.01 0.01 0.01
Medial 30° ER Lateral 0° Lateral 15° IR Lateral 30° IR Lateral 15° ER
0.3 0.1 0.1 0.1 0.1
0.6 0.5 0.4 0.5 0.5
0.47 0.24 0.23 0.24 0.27
0.11 0.15 0.14 0.14 0.14
0.01 0.02 0.02 0.02 0.02
Lateral 30° ER
0.1
0.5
0.25
0.14
0.02
was osteotomized transversely between the pins. Using a goniometer, the tibia was rotated 15° and 30° internally and externally and was fixed for each examination with a 4.5-mm narrow dynamic compression plate and 5 cortical screws. For each degree of rotation, pressure films were inserted into the medial and lateral knee compartments and axial force was applied. Each test was done twice, and the average contact pressure was calculated to decrease measurement error (Fig. 1). Because the knee was fixed and only the distal leg rotated, knee structures and capsule, patellofemoral and ligamentous tension were not affected by the tibial rotation. Intra‑articular contact pressure measurements After inserting the film into the joints and applying the load, the film was scanned using an HP Scanjet (G3110) with a resolution of 4,800*9,600 dpi (Fig. 2) and the scanned pictures were interpreted using Fujifilm calibration software. The maximum contact pressure for each specimen was then extracted in MPa with the accuracy of 0.1 MPa. Tehran University of Medical Science (Tehran, Iran) gave the IRB approval, and the ID number of the approval was 12219. The study was conformed to the Helsinki Declaration. Statistical analysis According to power analysis (power ratio 0.80 and type one error 0.05), six fresh whole-body cadavers was selected for this study. Table 2 Relative differences in medial and lateral compartments’ contact pressure due to different angles of tibial torsion
Average p value
IBM SPSS (version 19) for Windows was used for statistical analysis. Maximum and minimum values, variance, standard deviation, and mean of the medial and lateral compartment contact pressures before and after tibial torsion were calculated (Table 1). Nonparametric two-relatedsamples tests (Wilcoxon) were used to evaluate the significance of the differences observed in the medial and lateral compartment contact pressure. A p value of
KNEE
The effect of tibial rotation on knee medial and lateral compartment contact pressure Hamidreza Yazdi · Mohammadreza Mallakzadeh · Sara Sadat Farshidfar · Behrooz Givehchian · Hamidreza Daneshparvar · Hannes Behensky
Received: 17 August 2013 / Accepted: 10 September 2014 © European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2014
Abstract Purpose The progression of knee osteoarthritis (OA) is determined in part by mechanical effects on local structures. The mechanical influences of limb malalignment on cartilage loss are well known; however, the effect of rotational deformities on knee OA is not yet known. The aim of the current study was to evaluate the effect of tibial rotation on knee medial and lateral compartment contact pressure. Methods The left knees of six fresh whole-body cadavers were used in this study. Fujifilm Prescale super-low type film was used for contact pressure measurement. The films were inserted into the joint after arthrotomy. The cadavers were stabilized with a custom-made device, and axial force of half body weight specific to each cadaver was applied to the plantar surface of the feet. The examination was repeated after osteotomy of the fibula and tibia,
and the tibia was then rotated 15° or 30° internally (IR) or externally (ER) and securely fixed. The resulting films were scanned, and CP was determined using appropriate software. Results The p values for increased medial compartment contact pressure at 15° and 30° IR and 30° ER were 0.016, 0.025, and 0.025, respectively. For decreased medial compartment contact pressure at 15° ER, the p value was 0.020. The p values for increased lateral compartment contact pressure at 15° and 30° ER were 0.010 and 0.030, respectively. In this compartment, contact pressure changes at 15° and 30° IR were not significant. Conclusion This experimental study demonstrated that 15° IR of the tibial shaft increased contact pressure and 15° ER decreased contact pressure over the knee medial compartment. Keywords Knee · Contact pressure · Tibial rotation · Osteoarthritis
H. Yazdi (*) Department of Knee Surgery, Firoozgar Hospital, School of Medicine, Iran University of Medical Science, Tehran, Iran e-mail: [email protected] M. Mallakzadeh · S. Sadat Farshidfar Biomechanics Department, School of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran B. Givehchian Shafa Rehabilitation Hospital, School of Medicine, Iran University of Medical Science, Tehran, Iran H. Daneshparvar Legal Medicine Research Center, Legal Medicine Organization, Tehran, Iran H. Behensky Department of Orthopedic Surgery, Medical University Innsbruck, Innsbruck, Austria
Introduction Osteoarthritis (OA) of the knee accounts for a large percentage of disabilities of the lower extremities [10]. Poor understanding of the development of OA has led to the slow development of intervention that can modify the course of the disease [21]. To optimize the management of OA, it is important to increase the understanding of the predictors of its progression. If specific prognostic factors can be modified, it may be possible to decrease the progression of OA. Even if these prognostic factors cannot be modified, they can still be used to identify high-risk groups to allow modification of patient information and perspectives for medical treatment [4, 17].
13
Knee Surg Sports Traumatol Arthrosc
The progression of knee OA is determined in part by mechanical effects on local structures. One mechanical influence on cartilage loss is limb alignment [9, 14]. Several studies have examined the relationship between frontal plane malalignment and the progression of knee OA [6, 7, 14, 15, 19, 21, 22]. The relationship between lower limb torsion and knee pathology has been previously investigated [1, 8, 16, 23, 25], but no study has focused solely on the quantitative effect of tibial torsion on tibiofemoral contact pressure. One of the best methods to evaluate the effect of biomechanical factors on the progression of knee OA is to measure direct loading on a specific site on the knee. Measurements taken under dynamic loading should be used to assess the biomechanical function of the knee [19]. The current study evaluated the effect of tibial torsion on tibiofemoral contact pressure over the knee medial and lateral compartments. In contrast to previous studies, the effect of hip rotation and foot progression angle was deleted in this study.
Materials and methods Based on a power analysis (power ratio 0.80) the left knee of the six fresh whole-body cadavers with the mean age of 32.5 ± 8 years (range 20–45 years), mean height of 175.3 ± 10.1 cm (range 157–183 cm), and mean body mass of 68.3 ± 16.3 kg (range 40–85 kg), was used in this study. All cadavers were examined clinically and radiographically and were determined to have no tibial malrotation or coronal and sagittal deformities. Prescale pressure-sensitive super-low type film (Fujifilm, Japan, 2011) was used to measure contact pressure. The film was cut into the shape of the medial and lateral compartments of the knee and sealed between two 0.05-mm-thick polyethylene sheets to prevent damage from joint fluid. After a midline incision and medial and lateral parapatellar knee arthrotomy, the articular surfaces, ligaments, and menisci of all knees were evaluated and determined to be intact with no signs of recent trauma. The method recommended by Kenawey et al. [16] was used to perform a medial and lateral total meniscectomy to facilitate insertion of pressure film into the medial and lateral compartments of the joints. Weight bearing was simulated using a novel device that allows a defined axial force to be applied to the left lower limb of supine whole-body cadavers. The device was fixed to the body using pelvic and thigh straps. Fibulectomy was performed between the proximal 2/3 and distal 1/3 of the fibula to harvest 2 cm of bone to facilitate tibial rotation. After implanting the film, the knee
13
Fig. 1 Tibia rotated 15° externally and fixed with plate. Pressure films inserted into the medial and lateral compartment
Fig. 2 Red-colored Fujifilm obtained from the second sample
was fixed in full extension and the ankle was maintained in a neutral position. An axial force equivalent to half the body weight [16] specific to each specimen was constantly applied to the plantar surface of the foot for 2 min (protocol recommended by Fuji). The film was then removed. The tibial shaft was then exposed anteromedially, 2 parallel pins were inserted perpendicularly 2 cm apart into the mid-diaphysis of the tibia as reference points, and the tibia
Knee Surg Sports Traumatol Arthrosc Table 1 Descriptive statistics of medial and lateral compartments’ contact pressures before and after tibial torsion Minimum
Maximum
Mean
SD
Variance
Medial 0° Medial 15° IR Medial 30° IR Medial 15° ER
0.2 0.3 0.2 0.2
0.5 0.7 0.6 0.5
0.40 0.51 0.46 0.39
0.13 0.12 0.11 0.12
0.01 0.01 0.01 0.01
Medial 30° ER Lateral 0° Lateral 15° IR Lateral 30° IR Lateral 15° ER
0.3 0.1 0.1 0.1 0.1
0.6 0.5 0.4 0.5 0.5
0.47 0.24 0.23 0.24 0.27
0.11 0.15 0.14 0.14 0.14
0.01 0.02 0.02 0.02 0.02
Lateral 30° ER
0.1
0.5
0.25
0.14
0.02
was osteotomized transversely between the pins. Using a goniometer, the tibia was rotated 15° and 30° internally and externally and was fixed for each examination with a 4.5-mm narrow dynamic compression plate and 5 cortical screws. For each degree of rotation, pressure films were inserted into the medial and lateral knee compartments and axial force was applied. Each test was done twice, and the average contact pressure was calculated to decrease measurement error (Fig. 1). Because the knee was fixed and only the distal leg rotated, knee structures and capsule, patellofemoral and ligamentous tension were not affected by the tibial rotation. Intra‑articular contact pressure measurements After inserting the film into the joints and applying the load, the film was scanned using an HP Scanjet (G3110) with a resolution of 4,800*9,600 dpi (Fig. 2) and the scanned pictures were interpreted using Fujifilm calibration software. The maximum contact pressure for each specimen was then extracted in MPa with the accuracy of 0.1 MPa. Tehran University of Medical Science (Tehran, Iran) gave the IRB approval, and the ID number of the approval was 12219. The study was conformed to the Helsinki Declaration. Statistical analysis According to power analysis (power ratio 0.80 and type one error 0.05), six fresh whole-body cadavers was selected for this study. Table 2 Relative differences in medial and lateral compartments’ contact pressure due to different angles of tibial torsion
Average p value
IBM SPSS (version 19) for Windows was used for statistical analysis. Maximum and minimum values, variance, standard deviation, and mean of the medial and lateral compartment contact pressures before and after tibial torsion were calculated (Table 1). Nonparametric two-relatedsamples tests (Wilcoxon) were used to evaluate the significance of the differences observed in the medial and lateral compartment contact pressure. A p value of
