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Is latero-medial patellar mobility related to the range of motion of the knee joint after total knee arthroplasty?
Manual Therapy 15 (2010) 574e578
Contents lists available at ScienceDirect
Manual Therapy journal homepage: www.elsevier.com/math
Original article
Is latero-medial patellar mobility related to the range of motion of the knee joint after total knee arthroplasty?q Susumu Ota a, *, Takeshi Nakashima b, Ayako Morisaka b, Takaaki Omachi c, Kunio Ida d, Morio Kawamura e a
Department of Physical Therapy, School of Health Sciences, Nagoya University, 1-1-20 Daikominami, Higashi-ku, Nagoya, Aichi 461-8673, Japan Rehabilitation Center, Toyohashi Municipal Hospital, Toyohashi, Japan c Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan d Department of Orthopedic Surgery, Asahi Hospital, Kasugai, Japan e Department of Physical Therapy, Nagoya University Graduate School of Medicine, Nagoya, Japan b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 8 November 2009 Received in revised form 23 June 2010 Accepted 28 June 2010
Diminished range of motion (ROM) of the knee joint after total knee arthroplasty (TKA) is thought to be related to reduced patellar mobility. This has not been confirmed clinically due to a lack of quantitative methods adequate for measuring patellar mobility. We investigated the relationship between patellar mobility by a reported quantitative method and knee joint ROM after TKA. Forty-nine patients [osteoarthritis e OA: 29 knees; rheumatoid arthritis e RA: 20 knees] were examined after TKA. Respective medial and lateral patellar mobility was measured 1 and 6 months postoperatively using a patellofemoral arthrometer (PFA). Knee joint ROM was also measured in each of those 2 sessions. Although the flexion and extension of the knee joints improved significantly from 1 to 6 months after TKA, the medial and lateral patellar displacements (LPDs) failed to improve during that same period. Moreover, only the changes in knee flexion and medial patellar displacement (MPD) between the two sessions were positively correlated (r ¼ 0.31, p < 0.05). However, our findings demonstrated that medial and lateral patellar mobility had no sufficient longitudinal relationship with knee ROM after TKA. Ó 2010 Elsevier Ltd. All rights reserved.
Keywords: Knee Patellar mobility Knee range of motion Total knee arthroplasty
1. Introduction Total knee arthroplasty (TKA) is one of the most common and effective forms of intervention for patients with knee osteoarthritis (OA) or rheumatoid arthritis (RA) of the knee. However, clinically speaking, the range of motion (ROM) of the knee joints is reduced in some patients after TKA (Lu et al., 1999; Kim et al., 2004; Yercan et al., 2006). In particular, severe stiffness has been reported in the knee joint following TKA (Scranton, 2001; Mihalko and Whiteside, 2003), and limitations in knee ROM were found to directly affect activities of daily living (ADL). Knee ROM from 0 to 70 is necessary for normal walking (Perry, 1992), stair climbing requires knee flexion of 83 , rising from a seated position demands knee flexion of 90 , and 105 knee flexion is required for tying shoelaces (Laubenthal et al., 1972). Thus, one of the major challenges of rehabilitation after TKA is to achieve adequate knee ROM.
q The Ethics Committees of the School of Health Sciences, Nagoya University, and Toyohashi Municipal Hospital approved the protocol for this study. * Corresponding author. Tel./fax: þ81 527191365. E-mail address: [email protected] (S. Ota). 1356-689X/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.math.2010.06.009
Reduced patellar mobility has been reported in patients with patellofemoral pain (tightness of the lateral retinaculum) (Puniello, 1993; Fulkerson, 2004), knee arthrofibrosis after ligament reconstruction or articular fracture (Vaquero et al., 1993), and TKA (Jerosch and Aldawoudy, 2007). The limitation of patellar mobility is reportedly due to multiple factors such as suprapatellar pouch, peripatellar soft tissue, and the shortening of the patellar tendon due to arthroscopy (Vaquero et al., 1993; Jerosch and Aldawoudy, 2007). However, a method for quantitative measurement of patellar mobility in the clinical situation has not yet been established, so the tightness of patellar mobility in these reports is based on the objective evaluation. Therefore, the amount of patellar mobility with knee disorders has also not been reported. However, the recent development of a patellofemoral arthrometer (PFA) (Ota et al., 2006, 2008) has allowed for the quantification of medial and LPD in the frontal plane in a clinical setting. The application of such methods to a quantitative assessment in patients with knee contracture should help determine the quantitative level of medial and lateral patellar mobility after TKA as an effective first step in research related to patellar mobility. The present study was conducted to determine the amount of patellar mobility present after TKA and to establish the relationship between knee ROM and patellar mobility as a framework for a future clinical trial of patellar mobility after TKA.
S. Ota et al. / Manual Therapy 15 (2010) 574e578
2. Methods 2.1. Subjects This study set out to examine a total of 72 knees in 66 patients from a consecutive sample of those who underwent primary TKA between January 2005 and October 2006 at Toyohashi Municipal Hospital, Japan. The inclusion criteria were as follows: 1) a diagnosis of OA or RA; 2) an ability to achieve 30 flexion at the knee joint for patellar mobility assessment; 3) an agreement to attend two measurement sessions (1 and 6 months after TKA); 4), and a willingness to provide informed consent to participate in this research. Fifteen subjects, representing a total of 16 knees, were excluded since they failed to satisfy the above inclusion criteria (3, 3, 7, and 2 subjects for criteria 1), 2), 3), and 4), respectively). For each of 5 patients who underwent a bilateral TKA, a side was then selected at random. Since two patients with RA had undergone lateral release, the data on these patients were also excluded. Therefore, a total of 49 eligible post-TKA patients (total: 49 knees; OA: 29 knees; RA: 20 knees) were analyzed in this study. The patients were comprised of 9 males and 40 females. The mean standard deviation (SD) age, height, and body mass index (BMI) of the participants were 71 10 years, 153 9 cm, and 24 4 kg/m2, respectively. The mean SD preoperative knee flexion, extension, and femorotibial angles were 118 9 , 11 10 , and 185 9 , respectively. TKA was performed by two orthopaedic surgeons using the same components (cruciate retaining type) and procedures (resurfacing of the patella) under supervision of a senior surgeon. Osteophytes of the patella, and posterior osteophytes of the femur and tibia were removed. All patients gave their informed consent before participating in the study, and this research was approved by the Ethics Committees of the School of Health Sciences, Nagoya University, and Toyohashi Municipal Hospital. 2.2. Postoperative rehabilitation All patients were treated according to the critical pathway for TKA established by Toyohashi Municipal Hospital. On the second day after TKA, active and passive knee and hip ROM exercises were performed, patients were allowed to bear 10 kg of weight while wearing a knee brace, and standing and gait exercises were started using a walker or parallel bars. Weight bearing of up to 20 kg with a knee brace was permitted from one week after TKA. Full weight bearing without a knee brace was allowed from 2 weeks after TKA. The patients were hospitalized for around 4 weeks (after surgery and then discharged). From three days after TKA, all patients used a continuous passive movement device for an average of 3 h every day for three weeks. 2.3. Assessment of knee joint ROM Ten subjects, 10 knees (healthy subjects: 5 knees, patients with OA and RA: 1 and 4 knees, respectively,) participated in this reliability study of knee ROM. To assess the intra- and intertester reliability of quantified active knee ROM, repeated measurements were obtained by two different investigators (Testers 1 and 2: both physiotherapists with 6 and 3 years of experience, respectively) on two separate days. A standard goniometer was used to assess maximal active ROM in knee flexion and extension with the patient in a supine position (Magee, 1992; Lenssen et al., 2007). The bony landmarks identified were the greater trochanter, the lateral femoral condyle, and the lateral malleolus. The centre of the fulcrum was positioned over the lateral condyle of the femur. The proximal fixed arm of the goniometer was aligned with the axis
575
of the femur by using the greater trochanter as a reference point. The distal mobile arm was aligned using the lateral malleolus. Positive and negative values for knee extension represented hyperextension of the knee joint and knee flexion, respectively. Thus, negative values indicated a lack of full extension of the knee joint. The intraclass correlation coefficients (ICCs2,1) of the intratester reliability of measurements of the two testers for knee flexion and extension angle were, respectively, 0.96 (Tester 1, 95% confidence interval e CI: 0.84e0.99), 0.99 (Tester 2, 95% CI: 0.97e0.99) for knee flexion angle, 0.93 (Tester 1, 95% CI: 0.77e0.98), and 0.93 (Tester 2, 95% CI: 0.74e0.98) for knee extension angle. The ICC of the intertester reliability of the two testers’ measurements for knee flexion and extension angle were, respectively, 0.91 (day 1, 95% CI: 0.70e0.98), 0.97 (day 2, 95% CI: 0.90e0.99) for knee flexion angle, and 0.78 (day 1, 95% CI: 0.32e0.94), and 0.90 (day 2, 95% CI: 0.65e0.97) for knee extension angle. 2.4. Assessment of patellar mobility 2.4.1. Instrumentation To assess the level of passive patellar mobility, we used a modified PFA (Matsumoto P&O Co., Ltd., Aichi, Japan) (Ota et al., 2006, 2008) equipped with a digital calliper (Mitsutoyo Co., Kanagawa, Japan; Absolute Digimatic Calliper 500-151; resolution: 0.01 mm; accuracy: 0.02 mm) (Fig. 1). The device was stabilized by clamping it to the femoral condyles. The plane adjuster allowed the digital calliper to lie at an angle of 90 between the centre of the patella and the anterior superior iliac spine (ASIS), the same landmarks as those of the Q angle (Fig. 1) (Magee, 1992). The PFA was designed to measure patellar displacement during initial (fixed) frontal plane motion (medial and lateral translation in mm). 2.4.2. Procedures Passive patellar mobility was assessed using the PFA with the patient in bed in a supine position and the knee held at a flexion angle of 30 using rolled towels at a level determined with a standard goniometer. The neutral position of the leg (0 hip rotation) was confirmed at 90-degree knee flexion and hip flexion, and then the leg was extended. The leg was maintained by placing a cushion between the ankles, which were then bound together to prevent hip rotation. The PFA was clamped to the femoral condyles and aligned parallel to the bed. The digital calliper was positioned at an angle of 90 to the line between the centre of the patella and the ASIS using a plane adjuster (Fig. 1). Before each test, the level of pushing force (w80 N) was confirmed using a handheld MicroFET2 dynamometer (Hoggan Health Industries Inc., West Jordan, UT, USA) (Ota et al., 2008). The test subjects first relaxed on the bed in a supine position. To measure lateral patellar mobility, the lateral side of the patellar border was palpated and located with a laser using the adjustable laser module arm, and the digital calliper was set at zero to determine this point as the initial position. The lateral displacement of the patella was then determined by manually pushing the patella laterally (w80 N), at which point that side of the patella was again located by sliding the laser module arm on the calliper and reading the measurement (Fig. 2). During the assessment, the quadriceps were relaxed, which was confirmed by palpation of the quadriceps and passive movement of the patella medially and laterally as described previously (Joshi and Heatley, 2000). Medial passive patellar mobility was assessed in the same manner. All these passive patellar mobility procedures were performed by one investigator (either Tester 3 or 4 in the reliability study and Tester 3 in the patellar mobility study following TKA).
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2.4.3. Reliability The intra- and intertester reliability of this method had been confirmed by analyses of 30 healthy subjects (males: 15; females: 15) prior to the study. The mean age, height, and BMI of the participants were, respectively, 29 6 years (males: 29 7 years; females: 29 5 years), 167 8 cm (males: 173 5 cm; females: 161 4 cm), and 21.2 2.7 kg/m2 (males: 22.8 2.6 kg/m2; females: 19.5 1.5 kg/m2). The procedures used for the assessment of patellar mobility are as described above. To assess the intra- and intertester reliability in quantifying medial and lateral passive patellar mobility, repeated measurements were obtained on two separate days by two different investigators (Testers 3 and 4, who are physiotherapists with 12 and 6 years of experience, respectively). Prior to data collection, Testers 1 and 2 assessed ten participants for about 150 min (measurements in 10 subjects) to practice the technique and to determine the proper degree of laterally directed force applied to the patella with both thumbs until it stopped moving. Throughout the pre-test sessions, the manual pushing force at the end of patellar displacement was confirmed immediately after each measurement to be approximately 80 N using a handheld dynamometer. We also confirmed the pushing force using the handheld dynamometer before each measurement, after which Testers 3 and 4 then randomly measured patellar mobility in the same session for each subject, all of whom underwent two testing sessions at least two days apart. In all cases, measurements were made three times, with the final analysis performed using the mean of those three. Both investigators were blinded to their own measurements and those of the other tester. The intra- and intertester reliability of both medial and LPDs obtained with the PFA were assessed using ICC2,3 (Portney and Watkins, 2000). The standard error of the mean (SEM) (Deneger and Ball, 1993) was calculated using the following equation: SEM ¼ SD [O1 ICC]. After the reliability study, the patellofemoral study was started using the same procedures as in the practice session and the reliability study. Fig. 1. The patellofemoral arthrometer can be clamped to the femoral condyles. The plane adjuster allows the digital calliper to lie at an angle of 90 to the line between the centre of the patella and the anterior superior iliac spine (1: adjustable laser module arm, 2: plane adjuster).
2.5. Data analysis ROM of the knee joint along with patellar mobility were measured 1 and 6 months after TKA. Patellar mobility was measured three times, and the mean was used in the final analysis. Patellar mobility was assessed by Tester 3, and knee ROM was measured by Testers 1 and 2, the same two as in the reliability study for knee ROM. All assessments were performed in a blinded manner. The differences in patellar mobility and knee ROM between each measurement period were analyzed by a paired t-test. We used Pearson’s correlation coefficient to analyze the cross-sectional relationship between the changes in knee ROM and patellar mobility, with significance set at p < 0.05. All statistical analyses were performed using SPSS for Windows 16.0 (SPSS Inc., Chicago, IL, USA). Table 1 Reliability of patellar mobility using a patellofemoral arthrometer (n ¼ 30). Intratester
a
MPD (mm) LPDb (mm) a b
Fig. 2. Displacement of the patella was determined by measuring the difference between the initial position and the displaced position under the manual pushing force (approximately 80 N).
c d e
Intertester
ICCc (95% CId)
SEMe
ICCc (95% CId)
SEMe
0.87 (0.72e0.94) 0.96 (0.91e0.98)
0.67 0.74
0.72 (0.42e0.87) 0.91 (0.81e0.96)
1.09 1.08
MPD ¼ medial patellar displacement. LPD ¼ lateral patellar displacement. ICC ¼ intraclass correlation coefficient. CI ¼ confidence interval. SEM ¼ standard error of the mean.
S. Ota et al. / Manual Therapy 15 (2010) 574e578 Table 2 Average patellar mobility in the reliability study. Mean (SD)
Day 1 Tester 3
a
MPD (mm) LPDb (mm) a b
9.8 (1.8) 12.9 (3.7)
Day 2 Tester 4
Tester 3
10.4 (2.3) 12.5 (3.5)
9.5 (2.0) 13.3 (3.7)
Table 4 Correlation between changes in patellar mobility and knee ROM between 1 and 6 months after TKA.
MPDa LPDb
Flexion
Extension
0.31* 0.24
0.11 0.16
*p < 0.05. a MPD: medial patellar displacement. b LPD: lateral patellar displacement.
MPD ¼ medial patellar displacement. LPD ¼ lateral patellar displacement.
3. Results The ICC of the intra- and intertester reliability of the medial and LPDs at a knee flexion of 30 and of the mean patellar mobility are shown in Tables 1 and 2. Knee ROM and patellar displacement at 1 and 6 months after TKA are shown in Table 3. Between those periods, both knee flexion and extension, improved significantly. However, the medial and LPDs had not significantly changed. Although no correlations were observed between knee ROM and patellar displacement at either time point (Table 4), changes in medial patellar displacement (MPD) and knee flexion angle were positively correlated (p < 0.05). 4. Discussion The results of this study show a mean patellar displacement ranging between 6 to 7 mm in patients at 1 and 6 months after TKA. Previous studies (Skally et al., 1993; Fithian et al., 1995; Joshi and Heatley, 2000) on medial and lateral patellar mobility in healthy subjects revealed they range from around 9 to 10 mm and from around 8 to 15 mm, respectively. However, their research conditions as well as the level of patellar force and the angle of the knee joint differed from those in our report. Therefore, values of patellar mobility after TKA in our study cannot be directly compared to those obtained from healthy subjects in the above-mentioned studies. Even though our study presents only the range of medial and lateral patellar mobility after TKA, to our knowledge these displacements are here shown in a clinical study for the first time. Also, the reliability of this method was clinically acceptable (Portney and Watkins, 2000), so it would be applicable for other knee disorders. Although flexion and extension of the knee joint were improved from 1 to 6 months after TKA, neither the medial nor the lateral patellar mobility had changed. Changes in knee flexion and MPD from 1 to 6 months after TKA were positively correlated. However, the coefficient r (0.31) was quite low, so we could not conclude that a strong relationship exists between the knee flexion angle and MPD. The changes in knee extension and patellar displacement were not related. Medial and lateral restraint of the peripatellar soft tissue has been reported to increase progressively with knee flexion (above 30 ) (Farahmand et al., 1998; Senavogse et al., 2003; Yagishita et al., 2003). Tightness of the medial and lateral peripatellar soft tissue has also been reported to restrict patellar mobility in previous in vitro studies (Conlan et al., 1993; Desio et al., 1998; Hautamaa et al., 1998).
Table 3 Change of knee ROM and patellar displacement at 1 and 6 months after TKA. Mean (SD)
Flexion
Extension
MPDa
LPDb
1 month after TKA 6 months after TKA
94.1 (14.0) 106.2 (15.6)*
4.8 (8.2) 0.8 (7.8)*
6.7 (2.0) 6.7 (1.7)
7.6 (2.6) 7.2 (2.0)
*p < 0.01. a MPD: medial patellar displacement. b LPD: lateral patellar displacement.
577
These studies of the relationship between peripatellar soft tissue and both knee flexion angle and frontal patellar mobility suggested a relationship between medial and lateral patellar mobility and knee flexion. However, in light of this finding, the restriction of knee ROM (flexion) due to tightness of the patellar retinaculum (medial and lateral peripatellar soft tissues) may not have occurred after TKA. The flexion and extension of knee joints occur in the sagittal plane, thus suggesting that patellar mobility in the sagittal plane, and in the superior and inferior directions could be more effective in obtaining reliable knee ROM. The mobilization of the patella in the sagittal plane has been described as a manual therapy technique for knee ROM (Hall and Brody, 1999). Although quantitative methods to assess superior and inferior patellar mobility are currently lacking, the development of a subjective measurement for the sagittal plane direction would be the next logical step in investigating the relationship between patellar mobility and knee ROM. The present study has a number of limitations. First, patients with severe knee contracture, i.e., those incapable of 30 knee joint flexion, were excluded, since such patients may have severe tightness of the peripatellar tissue. Also because the minimum knee flexion and extension in patients after 6 month with TKA are 80 and 15 , respectively, we assume that there is no remarkable arthrofibrosis (stiff knee) in this study (Kim et al., 2004). However, if the patients suffer from arthrofibrosis after TKA, a tightening of the medial and lateral peripatellar soft tissues and adhesion of the suprapatellar pouch and the medial and lateral gutters might restrict patellar mobility (Vaquero et al., 1993; Jerosch and Aldawoudy, 2007). Second, we combined the data of patients with OA and RA because of the small number of post-TKA knees. Of course, if larger sample populations were measured, a different result might be obtained. We found that there is no sufficient longitudinal relationship between patellar mobility in the frontal plane and knee ROM in the sagittal plane. Objective values of medial and lateral patellar mobility are presented in this study as a first step in a framework designed for future clinical trials. However, superior and inferior measurement data need to be included in future post-TKA studies of multi-directional patellar mobility. 5. Conclusion Objective values of patellar mobility in the frontal plane after TKA are presented in this study as steps toward a framework for future research. There were no sufficient longitudinal relationships observed between patellar mobility and knee ROM after TKA. In future research, we hope to further investigate patellar mobility in the sagittal plane as a cause of limited knee ROM. References Conlan T, Garth WP, Lemons JE. Evaluation of the medial soft-tissue restraints of the extensor mechanism of the knee. Journal of Bone and Joint Surgery American Volume 1993;75A(5):682e93. Deneger CR, Ball DW. Assessing reliability and precision of measurement: an introduction to intraclass correlation and standard error of measurement. Journal of Sports Rehabilitation 1993;2:35e42.
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Desio SM, Burk RT, Bachus KN. Soft tissue restraints to lateral patellar translation in the human knee. American Journal of Sports Medicine 1998;26(1):59e65. Farahmand F, Tahmasbi MN, Amis AA. Lateral forceedisplacement behaviour of the human patella and its variation with knee flexion: a biomechanical study in vitro. Journal of Biomechanics 1998;31:1147e52. Fithian DC, Mishra DK, Balen PF, Stone ML, Daniel DM. Instrumented measurement of patellar mobility. American Journal of Sports Medicine 1995;23(5):607e15. Fulkerson JP. Disorder of the patellofemoral joint. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2004. Hall CM, Brody LT. Therapeutic exercise: moving toward function. Philadelphia: Lippincott Williams & Wilkins; 1999. Hautamaa PV, Fithian DC, Kaufman KR, Daniel DM, Pohlmeyer AM. Medial soft tissue restraints in lateral patellar instability and repair. Clinical Orthopaedics and Related Research 1998;349:174e82. Jerosch J, Aldawoudy AM. Arthroscopic treatment of patients with moderate arthrofibrosis after total knee replacement. Knee Surgery, Sports Traumatology, Arthroscopy 2007;15(1):71e7. Joshi RP, Heatley FW. Measurement of coronal plane patellar mobility in normal subjects. Knee Surgery, Sports Traumatology, Arthroscopy 2000;8(1):40e5. Kim J, Nelson CL, Lotke PA. Stiffness after total knee arthroplasty: prevalence of the complication and outcomes of revision. Journal of Bone and Joint Surgery, American Volume 2004;86A(7):1479e84. Laubenthal KN, Smidt GL, Kettlekamp DB. A quantitative analysis of knee motion during activities of daily living. Physical Therapy 1972;52(1):34e43. Lenssen AF, van Dam EM, Crijns YH, Verhey M, Geesink RJ, van den Brandt PA, et al. Reproducibility of goniometric measurement of the knee in the in-hospital phase following total knee arthroplasty. BMC Musculoskeletal Disorders 2007;8:83. Lu HS, Mow CS, Lin JH. Total knee arthroplasty in the presence of severe flexion contracture: a report of 37 cases. Journal of Arthroplasty 1999;14(7):775e80. Magee DJ. Orthopedic physical assessment. 2nd ed. Philadelphia: WB Saunders Company; 1992.
Mihalko WM, Whiteside LA. Bone resection and ligament treatment for flexion contracture in knee arthroplasty. Clinical Orthopaedics and Related Research 2003;406:141e7. Ota S, Nakashima T, Morisaka A, Ida K, Kawamura M. Comparison of patellar mobility in female adults with and without patellofemoral pain. Journal of Orthopaedic and Sports Physical Therapy 2008;38(7):396e402. Ota S, Ward SR, Chen YJ, Tsai YJ, Powers CM. Concurrent criterion-related validity and reliability of a clinical device used to assess lateral patellar displacement. Journal of Orthopaedic and Sports Physical Therapy 2006;36(9):645e52. Perry J. Gait analysis. New Jersey: SLACK Incorporated; 1992. Portney LG, Watkins MP. Foundations of clinical research: applications to practice. 2nd ed. Upper Saddle River, NJ: Prentice-Hall Health; 2000. Puniello MS. Iliotibial band tightness and medial patellar glide in patients with patellofemoral dysfunction. Journal of Orthopaedic and Sports Physical Therapy 1993;17(3):144e8. Scranton Jr PE. Management of knee pain and stiffness after total knee arthroplasty. Journal of Arthroplasty 2001;16(4):428e35. Senavogse W, Farahmand F, Jones J, Andersen H, Bull AMJ, Amis AA. Quantitative measurement of patellofemoral joint instability: forceedisplacement behavior of the human patella in vitro. Journal of Orthopaedic Research 2003;21:780e6. Skally TC, Terry GC, Teitge RA. The quantitative patellar measurement of normal passive medial and lateral motion limits. American Journal of Sports Medicine 1993;21(5):728e32. Vaquero J, Vidal C, Medina E, Baena J. Arthroscopic lysis in knee arthrofibrosis. Arthroscopy 1993;9(6):691e4. Yagishita K, Muneta T, Ikeda H. Step-by-step measurements of soft tissue balancing during total knee arthroplasty for the patients with varus knee. Journal of Arthroplasty 2003;18(3):313e20. Yercan HS, Sugun TS, Bussiere C, Ait Si Selmi T, Davies A, Neyret P. Stiffness after total knee arthroplasty: prevalence, management and outcomes. Knee 2006; 13(2):111e7.
Contents lists available at ScienceDirect
Manual Therapy journal homepage: www.elsevier.com/math
Original article
Is latero-medial patellar mobility related to the range of motion of the knee joint after total knee arthroplasty?q Susumu Ota a, *, Takeshi Nakashima b, Ayako Morisaka b, Takaaki Omachi c, Kunio Ida d, Morio Kawamura e a
Department of Physical Therapy, School of Health Sciences, Nagoya University, 1-1-20 Daikominami, Higashi-ku, Nagoya, Aichi 461-8673, Japan Rehabilitation Center, Toyohashi Municipal Hospital, Toyohashi, Japan c Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan d Department of Orthopedic Surgery, Asahi Hospital, Kasugai, Japan e Department of Physical Therapy, Nagoya University Graduate School of Medicine, Nagoya, Japan b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 8 November 2009 Received in revised form 23 June 2010 Accepted 28 June 2010
Diminished range of motion (ROM) of the knee joint after total knee arthroplasty (TKA) is thought to be related to reduced patellar mobility. This has not been confirmed clinically due to a lack of quantitative methods adequate for measuring patellar mobility. We investigated the relationship between patellar mobility by a reported quantitative method and knee joint ROM after TKA. Forty-nine patients [osteoarthritis e OA: 29 knees; rheumatoid arthritis e RA: 20 knees] were examined after TKA. Respective medial and lateral patellar mobility was measured 1 and 6 months postoperatively using a patellofemoral arthrometer (PFA). Knee joint ROM was also measured in each of those 2 sessions. Although the flexion and extension of the knee joints improved significantly from 1 to 6 months after TKA, the medial and lateral patellar displacements (LPDs) failed to improve during that same period. Moreover, only the changes in knee flexion and medial patellar displacement (MPD) between the two sessions were positively correlated (r ¼ 0.31, p < 0.05). However, our findings demonstrated that medial and lateral patellar mobility had no sufficient longitudinal relationship with knee ROM after TKA. Ó 2010 Elsevier Ltd. All rights reserved.
Keywords: Knee Patellar mobility Knee range of motion Total knee arthroplasty
1. Introduction Total knee arthroplasty (TKA) is one of the most common and effective forms of intervention for patients with knee osteoarthritis (OA) or rheumatoid arthritis (RA) of the knee. However, clinically speaking, the range of motion (ROM) of the knee joints is reduced in some patients after TKA (Lu et al., 1999; Kim et al., 2004; Yercan et al., 2006). In particular, severe stiffness has been reported in the knee joint following TKA (Scranton, 2001; Mihalko and Whiteside, 2003), and limitations in knee ROM were found to directly affect activities of daily living (ADL). Knee ROM from 0 to 70 is necessary for normal walking (Perry, 1992), stair climbing requires knee flexion of 83 , rising from a seated position demands knee flexion of 90 , and 105 knee flexion is required for tying shoelaces (Laubenthal et al., 1972). Thus, one of the major challenges of rehabilitation after TKA is to achieve adequate knee ROM.
q The Ethics Committees of the School of Health Sciences, Nagoya University, and Toyohashi Municipal Hospital approved the protocol for this study. * Corresponding author. Tel./fax: þ81 527191365. E-mail address: [email protected] (S. Ota). 1356-689X/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.math.2010.06.009
Reduced patellar mobility has been reported in patients with patellofemoral pain (tightness of the lateral retinaculum) (Puniello, 1993; Fulkerson, 2004), knee arthrofibrosis after ligament reconstruction or articular fracture (Vaquero et al., 1993), and TKA (Jerosch and Aldawoudy, 2007). The limitation of patellar mobility is reportedly due to multiple factors such as suprapatellar pouch, peripatellar soft tissue, and the shortening of the patellar tendon due to arthroscopy (Vaquero et al., 1993; Jerosch and Aldawoudy, 2007). However, a method for quantitative measurement of patellar mobility in the clinical situation has not yet been established, so the tightness of patellar mobility in these reports is based on the objective evaluation. Therefore, the amount of patellar mobility with knee disorders has also not been reported. However, the recent development of a patellofemoral arthrometer (PFA) (Ota et al., 2006, 2008) has allowed for the quantification of medial and LPD in the frontal plane in a clinical setting. The application of such methods to a quantitative assessment in patients with knee contracture should help determine the quantitative level of medial and lateral patellar mobility after TKA as an effective first step in research related to patellar mobility. The present study was conducted to determine the amount of patellar mobility present after TKA and to establish the relationship between knee ROM and patellar mobility as a framework for a future clinical trial of patellar mobility after TKA.
S. Ota et al. / Manual Therapy 15 (2010) 574e578
2. Methods 2.1. Subjects This study set out to examine a total of 72 knees in 66 patients from a consecutive sample of those who underwent primary TKA between January 2005 and October 2006 at Toyohashi Municipal Hospital, Japan. The inclusion criteria were as follows: 1) a diagnosis of OA or RA; 2) an ability to achieve 30 flexion at the knee joint for patellar mobility assessment; 3) an agreement to attend two measurement sessions (1 and 6 months after TKA); 4), and a willingness to provide informed consent to participate in this research. Fifteen subjects, representing a total of 16 knees, were excluded since they failed to satisfy the above inclusion criteria (3, 3, 7, and 2 subjects for criteria 1), 2), 3), and 4), respectively). For each of 5 patients who underwent a bilateral TKA, a side was then selected at random. Since two patients with RA had undergone lateral release, the data on these patients were also excluded. Therefore, a total of 49 eligible post-TKA patients (total: 49 knees; OA: 29 knees; RA: 20 knees) were analyzed in this study. The patients were comprised of 9 males and 40 females. The mean standard deviation (SD) age, height, and body mass index (BMI) of the participants were 71 10 years, 153 9 cm, and 24 4 kg/m2, respectively. The mean SD preoperative knee flexion, extension, and femorotibial angles were 118 9 , 11 10 , and 185 9 , respectively. TKA was performed by two orthopaedic surgeons using the same components (cruciate retaining type) and procedures (resurfacing of the patella) under supervision of a senior surgeon. Osteophytes of the patella, and posterior osteophytes of the femur and tibia were removed. All patients gave their informed consent before participating in the study, and this research was approved by the Ethics Committees of the School of Health Sciences, Nagoya University, and Toyohashi Municipal Hospital. 2.2. Postoperative rehabilitation All patients were treated according to the critical pathway for TKA established by Toyohashi Municipal Hospital. On the second day after TKA, active and passive knee and hip ROM exercises were performed, patients were allowed to bear 10 kg of weight while wearing a knee brace, and standing and gait exercises were started using a walker or parallel bars. Weight bearing of up to 20 kg with a knee brace was permitted from one week after TKA. Full weight bearing without a knee brace was allowed from 2 weeks after TKA. The patients were hospitalized for around 4 weeks (after surgery and then discharged). From three days after TKA, all patients used a continuous passive movement device for an average of 3 h every day for three weeks. 2.3. Assessment of knee joint ROM Ten subjects, 10 knees (healthy subjects: 5 knees, patients with OA and RA: 1 and 4 knees, respectively,) participated in this reliability study of knee ROM. To assess the intra- and intertester reliability of quantified active knee ROM, repeated measurements were obtained by two different investigators (Testers 1 and 2: both physiotherapists with 6 and 3 years of experience, respectively) on two separate days. A standard goniometer was used to assess maximal active ROM in knee flexion and extension with the patient in a supine position (Magee, 1992; Lenssen et al., 2007). The bony landmarks identified were the greater trochanter, the lateral femoral condyle, and the lateral malleolus. The centre of the fulcrum was positioned over the lateral condyle of the femur. The proximal fixed arm of the goniometer was aligned with the axis
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of the femur by using the greater trochanter as a reference point. The distal mobile arm was aligned using the lateral malleolus. Positive and negative values for knee extension represented hyperextension of the knee joint and knee flexion, respectively. Thus, negative values indicated a lack of full extension of the knee joint. The intraclass correlation coefficients (ICCs2,1) of the intratester reliability of measurements of the two testers for knee flexion and extension angle were, respectively, 0.96 (Tester 1, 95% confidence interval e CI: 0.84e0.99), 0.99 (Tester 2, 95% CI: 0.97e0.99) for knee flexion angle, 0.93 (Tester 1, 95% CI: 0.77e0.98), and 0.93 (Tester 2, 95% CI: 0.74e0.98) for knee extension angle. The ICC of the intertester reliability of the two testers’ measurements for knee flexion and extension angle were, respectively, 0.91 (day 1, 95% CI: 0.70e0.98), 0.97 (day 2, 95% CI: 0.90e0.99) for knee flexion angle, and 0.78 (day 1, 95% CI: 0.32e0.94), and 0.90 (day 2, 95% CI: 0.65e0.97) for knee extension angle. 2.4. Assessment of patellar mobility 2.4.1. Instrumentation To assess the level of passive patellar mobility, we used a modified PFA (Matsumoto P&O Co., Ltd., Aichi, Japan) (Ota et al., 2006, 2008) equipped with a digital calliper (Mitsutoyo Co., Kanagawa, Japan; Absolute Digimatic Calliper 500-151; resolution: 0.01 mm; accuracy: 0.02 mm) (Fig. 1). The device was stabilized by clamping it to the femoral condyles. The plane adjuster allowed the digital calliper to lie at an angle of 90 between the centre of the patella and the anterior superior iliac spine (ASIS), the same landmarks as those of the Q angle (Fig. 1) (Magee, 1992). The PFA was designed to measure patellar displacement during initial (fixed) frontal plane motion (medial and lateral translation in mm). 2.4.2. Procedures Passive patellar mobility was assessed using the PFA with the patient in bed in a supine position and the knee held at a flexion angle of 30 using rolled towels at a level determined with a standard goniometer. The neutral position of the leg (0 hip rotation) was confirmed at 90-degree knee flexion and hip flexion, and then the leg was extended. The leg was maintained by placing a cushion between the ankles, which were then bound together to prevent hip rotation. The PFA was clamped to the femoral condyles and aligned parallel to the bed. The digital calliper was positioned at an angle of 90 to the line between the centre of the patella and the ASIS using a plane adjuster (Fig. 1). Before each test, the level of pushing force (w80 N) was confirmed using a handheld MicroFET2 dynamometer (Hoggan Health Industries Inc., West Jordan, UT, USA) (Ota et al., 2008). The test subjects first relaxed on the bed in a supine position. To measure lateral patellar mobility, the lateral side of the patellar border was palpated and located with a laser using the adjustable laser module arm, and the digital calliper was set at zero to determine this point as the initial position. The lateral displacement of the patella was then determined by manually pushing the patella laterally (w80 N), at which point that side of the patella was again located by sliding the laser module arm on the calliper and reading the measurement (Fig. 2). During the assessment, the quadriceps were relaxed, which was confirmed by palpation of the quadriceps and passive movement of the patella medially and laterally as described previously (Joshi and Heatley, 2000). Medial passive patellar mobility was assessed in the same manner. All these passive patellar mobility procedures were performed by one investigator (either Tester 3 or 4 in the reliability study and Tester 3 in the patellar mobility study following TKA).
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2.4.3. Reliability The intra- and intertester reliability of this method had been confirmed by analyses of 30 healthy subjects (males: 15; females: 15) prior to the study. The mean age, height, and BMI of the participants were, respectively, 29 6 years (males: 29 7 years; females: 29 5 years), 167 8 cm (males: 173 5 cm; females: 161 4 cm), and 21.2 2.7 kg/m2 (males: 22.8 2.6 kg/m2; females: 19.5 1.5 kg/m2). The procedures used for the assessment of patellar mobility are as described above. To assess the intra- and intertester reliability in quantifying medial and lateral passive patellar mobility, repeated measurements were obtained on two separate days by two different investigators (Testers 3 and 4, who are physiotherapists with 12 and 6 years of experience, respectively). Prior to data collection, Testers 1 and 2 assessed ten participants for about 150 min (measurements in 10 subjects) to practice the technique and to determine the proper degree of laterally directed force applied to the patella with both thumbs until it stopped moving. Throughout the pre-test sessions, the manual pushing force at the end of patellar displacement was confirmed immediately after each measurement to be approximately 80 N using a handheld dynamometer. We also confirmed the pushing force using the handheld dynamometer before each measurement, after which Testers 3 and 4 then randomly measured patellar mobility in the same session for each subject, all of whom underwent two testing sessions at least two days apart. In all cases, measurements were made three times, with the final analysis performed using the mean of those three. Both investigators were blinded to their own measurements and those of the other tester. The intra- and intertester reliability of both medial and LPDs obtained with the PFA were assessed using ICC2,3 (Portney and Watkins, 2000). The standard error of the mean (SEM) (Deneger and Ball, 1993) was calculated using the following equation: SEM ¼ SD [O1 ICC]. After the reliability study, the patellofemoral study was started using the same procedures as in the practice session and the reliability study. Fig. 1. The patellofemoral arthrometer can be clamped to the femoral condyles. The plane adjuster allows the digital calliper to lie at an angle of 90 to the line between the centre of the patella and the anterior superior iliac spine (1: adjustable laser module arm, 2: plane adjuster).
2.5. Data analysis ROM of the knee joint along with patellar mobility were measured 1 and 6 months after TKA. Patellar mobility was measured three times, and the mean was used in the final analysis. Patellar mobility was assessed by Tester 3, and knee ROM was measured by Testers 1 and 2, the same two as in the reliability study for knee ROM. All assessments were performed in a blinded manner. The differences in patellar mobility and knee ROM between each measurement period were analyzed by a paired t-test. We used Pearson’s correlation coefficient to analyze the cross-sectional relationship between the changes in knee ROM and patellar mobility, with significance set at p < 0.05. All statistical analyses were performed using SPSS for Windows 16.0 (SPSS Inc., Chicago, IL, USA). Table 1 Reliability of patellar mobility using a patellofemoral arthrometer (n ¼ 30). Intratester
a
MPD (mm) LPDb (mm) a b
Fig. 2. Displacement of the patella was determined by measuring the difference between the initial position and the displaced position under the manual pushing force (approximately 80 N).
c d e
Intertester
ICCc (95% CId)
SEMe
ICCc (95% CId)
SEMe
0.87 (0.72e0.94) 0.96 (0.91e0.98)
0.67 0.74
0.72 (0.42e0.87) 0.91 (0.81e0.96)
1.09 1.08
MPD ¼ medial patellar displacement. LPD ¼ lateral patellar displacement. ICC ¼ intraclass correlation coefficient. CI ¼ confidence interval. SEM ¼ standard error of the mean.
S. Ota et al. / Manual Therapy 15 (2010) 574e578 Table 2 Average patellar mobility in the reliability study. Mean (SD)
Day 1 Tester 3
a
MPD (mm) LPDb (mm) a b
9.8 (1.8) 12.9 (3.7)
Day 2 Tester 4
Tester 3
10.4 (2.3) 12.5 (3.5)
9.5 (2.0) 13.3 (3.7)
Table 4 Correlation between changes in patellar mobility and knee ROM between 1 and 6 months after TKA.
MPDa LPDb
Flexion
Extension
0.31* 0.24
0.11 0.16
*p < 0.05. a MPD: medial patellar displacement. b LPD: lateral patellar displacement.
MPD ¼ medial patellar displacement. LPD ¼ lateral patellar displacement.
3. Results The ICC of the intra- and intertester reliability of the medial and LPDs at a knee flexion of 30 and of the mean patellar mobility are shown in Tables 1 and 2. Knee ROM and patellar displacement at 1 and 6 months after TKA are shown in Table 3. Between those periods, both knee flexion and extension, improved significantly. However, the medial and LPDs had not significantly changed. Although no correlations were observed between knee ROM and patellar displacement at either time point (Table 4), changes in medial patellar displacement (MPD) and knee flexion angle were positively correlated (p < 0.05). 4. Discussion The results of this study show a mean patellar displacement ranging between 6 to 7 mm in patients at 1 and 6 months after TKA. Previous studies (Skally et al., 1993; Fithian et al., 1995; Joshi and Heatley, 2000) on medial and lateral patellar mobility in healthy subjects revealed they range from around 9 to 10 mm and from around 8 to 15 mm, respectively. However, their research conditions as well as the level of patellar force and the angle of the knee joint differed from those in our report. Therefore, values of patellar mobility after TKA in our study cannot be directly compared to those obtained from healthy subjects in the above-mentioned studies. Even though our study presents only the range of medial and lateral patellar mobility after TKA, to our knowledge these displacements are here shown in a clinical study for the first time. Also, the reliability of this method was clinically acceptable (Portney and Watkins, 2000), so it would be applicable for other knee disorders. Although flexion and extension of the knee joint were improved from 1 to 6 months after TKA, neither the medial nor the lateral patellar mobility had changed. Changes in knee flexion and MPD from 1 to 6 months after TKA were positively correlated. However, the coefficient r (0.31) was quite low, so we could not conclude that a strong relationship exists between the knee flexion angle and MPD. The changes in knee extension and patellar displacement were not related. Medial and lateral restraint of the peripatellar soft tissue has been reported to increase progressively with knee flexion (above 30 ) (Farahmand et al., 1998; Senavogse et al., 2003; Yagishita et al., 2003). Tightness of the medial and lateral peripatellar soft tissue has also been reported to restrict patellar mobility in previous in vitro studies (Conlan et al., 1993; Desio et al., 1998; Hautamaa et al., 1998).
Table 3 Change of knee ROM and patellar displacement at 1 and 6 months after TKA. Mean (SD)
Flexion
Extension
MPDa
LPDb
1 month after TKA 6 months after TKA
94.1 (14.0) 106.2 (15.6)*
4.8 (8.2) 0.8 (7.8)*
6.7 (2.0) 6.7 (1.7)
7.6 (2.6) 7.2 (2.0)
*p < 0.01. a MPD: medial patellar displacement. b LPD: lateral patellar displacement.
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These studies of the relationship between peripatellar soft tissue and both knee flexion angle and frontal patellar mobility suggested a relationship between medial and lateral patellar mobility and knee flexion. However, in light of this finding, the restriction of knee ROM (flexion) due to tightness of the patellar retinaculum (medial and lateral peripatellar soft tissues) may not have occurred after TKA. The flexion and extension of knee joints occur in the sagittal plane, thus suggesting that patellar mobility in the sagittal plane, and in the superior and inferior directions could be more effective in obtaining reliable knee ROM. The mobilization of the patella in the sagittal plane has been described as a manual therapy technique for knee ROM (Hall and Brody, 1999). Although quantitative methods to assess superior and inferior patellar mobility are currently lacking, the development of a subjective measurement for the sagittal plane direction would be the next logical step in investigating the relationship between patellar mobility and knee ROM. The present study has a number of limitations. First, patients with severe knee contracture, i.e., those incapable of 30 knee joint flexion, were excluded, since such patients may have severe tightness of the peripatellar tissue. Also because the minimum knee flexion and extension in patients after 6 month with TKA are 80 and 15 , respectively, we assume that there is no remarkable arthrofibrosis (stiff knee) in this study (Kim et al., 2004). However, if the patients suffer from arthrofibrosis after TKA, a tightening of the medial and lateral peripatellar soft tissues and adhesion of the suprapatellar pouch and the medial and lateral gutters might restrict patellar mobility (Vaquero et al., 1993; Jerosch and Aldawoudy, 2007). Second, we combined the data of patients with OA and RA because of the small number of post-TKA knees. Of course, if larger sample populations were measured, a different result might be obtained. We found that there is no sufficient longitudinal relationship between patellar mobility in the frontal plane and knee ROM in the sagittal plane. Objective values of medial and lateral patellar mobility are presented in this study as a first step in a framework designed for future clinical trials. However, superior and inferior measurement data need to be included in future post-TKA studies of multi-directional patellar mobility. 5. Conclusion Objective values of patellar mobility in the frontal plane after TKA are presented in this study as steps toward a framework for future research. There were no sufficient longitudinal relationships observed between patellar mobility and knee ROM after TKA. In future research, we hope to further investigate patellar mobility in the sagittal plane as a cause of limited knee ROM. References Conlan T, Garth WP, Lemons JE. Evaluation of the medial soft-tissue restraints of the extensor mechanism of the knee. Journal of Bone and Joint Surgery American Volume 1993;75A(5):682e93. Deneger CR, Ball DW. Assessing reliability and precision of measurement: an introduction to intraclass correlation and standard error of measurement. Journal of Sports Rehabilitation 1993;2:35e42.
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