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Generation II knee bracing for severe medial compartment osteoarthritis of the knee
745
Generation II Knee Bracing for Severe Medial Compartment Osteoarthritis of the Knee Hiroaki Matsuno,
MD, PhD, Ken Morris Kadowaki, MD, PhD, Haruo Tsuji, MD, PhD
ABSTRACT. Matsuno H, Kadowaki KM, Tsuji H. Generation II knee bracing for severe medial compartment osteoarthritis of the knee. Arch Phys Med Rehabil 1997;78: 745-9. Objective: To investigate the clinical efficacy of the Generation II (G II) knee brace, a newly developed knee orthosis, on patients experiencing severe medial compartment osteoarthritis (OA) of the knee. Design: Case series. Setting: A national medical and pharmaceutical hospital in Japan. Patients: Twenty primary OA subjects (excluding those with secondary OA), all older than 55 years of age and experiencing only knee joint problems, were selected according to their ability to walk more than 500 meters independent of support. These patients had arthritis in both knees and no less than one half of normal joint space remaining as revealed by roentgenogram studies. The more severely affected side was selected for bracing. Interventions: For 12 months, each patient wore a G II knee brace on the affected knee on a daily basis, removing it only at night. To evaluate the effects of G II OA brace alone, additional use of new oral drugs or any other treatment was prohibited from 1 month before application of the G II OA brace and throughout the trial period. Main Outcome Measures: Clinical efficacy was evaluated using the Japan Orthopaedic Association’s knee scoring system. X-ray evaluation was performed with patients standing on one leg. A dynamometer was used to evaluate isokinetic quadriceps muscle strength. The center of gravity was measured using an X-Y recording. Clinical evaluation was performed every 2 months thereafter. Final evaluation was at 12 months. Results: Nineteen of the 20 patients answered that they experienced significant pain relief. Knee pain scores on walking increased from 18.0 to 21.5 and on ascending and descending stairs increased from 12.8 to 15.8. The femorotibial angle decreased in 12 of the patients, and the mean angle decreased from 185.1” before application to 183.7” with the brace on at the final observation period. In addition, isokinetic quadriceps muscle strength increased from an average of 36.8Nm to 428Nm for all patients. In 17 patients, quadriceps muscle strength increased, while it decreased in 2 and remained the From the Department of Orthopaedic Surgery, Toyama Medical and Pharmaceutical University, Toyama City, Japan. Submitted for publication July 19, 1996. Accepted in revised form January 10, 1997. Supported by a grant from Generation II USA, Inc. No commercial party having a direct or indirect interest in the subject matter of this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated. Reprint requests to Hiroaki Matsuno MD, PhD, Department of Orthopaedic Surgery, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama City, Japan. 0 1997 bv the American Conmess of Rehabilitation Medicine and the American Academy oi Physical Medicine-and Rehabilitation 0003-9993/97/7807-4116$3.00/O
same in 1. Finally, lateral movement of the center of gravity decreased compared with before G II application in all patients. Conclusion: G II bracing is a beneficial treatment for severe medial OA of the knee. 0 1997 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation STEOARTHRITIS (OA) of the knee is not an uncommon in a person of advanced age.’ From his study of 01,002disease dissection cases,Heine’ concluded that OA occurred most commonly in knee joints; moreover, more than 90% of the OAs occurred in persons 60 years of age or older. This study correlates with the clinical and roentgenologic assessmentof Kellgren and Lawrence,* wherein more than 80% of persons 55 years old or older experienced OA. In addition, many other reports3 conclude mat OA is strongly influenced by age and, accordingly, the occurrence increases linearly. At present, the Japanese health care system is facing a rapid increase in the number of aged persons. In 1965, 9.7% of the population was older than 60; in 1980, 12.9% were older than 60; by 1990, 17.6% had reached this age.4 It is well known that this population is at a much higher risk for surgical and anesthetic procedures.5s8Goldberg4 reported that the operative risk to aged OA patients was related to their declining general medical condition. In particular, such patients experienced more cardiovascular and respiratory diseases.Specific to Japan for example, cardiovascular diseaseis 3.5 times higher in persons older than 55.4 Therefore, to avoid surgery whenever possible, an alternative procedure would be useful. A wedge insole orthosis has already been used for OA patients in Japan. That treatment modality however, has been shown to be effective only in early-stage OA; severe OA is not affected. 9,10Thus, a more effective therapy is needed. Further, as the demographics discussedabove change, the number of patients who will be good candidates for bracing will also increase. The Generation II (G II) brace was designed in Canada by Generation II Orthotics Ltd.” The company developed a polyaxially hinged brace that allows the normal motion of a patient’s knee. The hinge mechanism has been adapted to an OA brace which is designed to provide relief for the pain associated with OA (fig 1). The brace is custom-made and consists of an ultrahigh molecular weight (UHMW) polyethylene thigh shell connected to a UHMW polyethylene calf shell via the polyaxial hinge on the medial side. The other key feature is a nylon tensioning strap on the lateral side. In Japan, the average size is 45cm in length and the weight is 700 grams (fig 2). The distinctive feature of this brace is the polyaxial hinge, which is used to enlarge the joint space at, for example, the medial femorotibial compartment of the knee (fig 3). When the brace has been applied, and the knee is flexed to 60”, the hinge is bent into valgus for the sagittal plane of the patient’s knee extension condition, allowing the knee joint space to enlarge. As the patient flexes his or her knee to its full 130”, the hinge continues to bend into valgus until the angle formed reaches 30” in the sagittal knee extension
Arch
Phys
Med Rehabil
Vol78,
July
1997
746
G II KNEE
BRACING
IN OA
PATIENTS,
Matsuno
Fig 2. Structure,
Fig 1. The G II brace consists of both a thigh and a calf strap that connected by a diagonal strap. (A) On the medial side of the knee single, polyaxial hinge. (B) Lateral view.
are is a
condition. This allows more normalized conditions when the knee is flexed and thus decreases pain levels. If the medial joint space in OA patients could be enlarged using this orthosis, their painful symptoms could be eliminated or decreased. The purpose of this study was to examine the effect of this G II brace on patients suffering from OA of the knee.
PATIENTS AND METHODS Patients. The patients were 4 men and 16 women 58 to 84 years (average 76.6). All experienced only
aged knee
Phys Med
Rehabil
Vol 78, July
1997
and material
of the G II OA brace.
joint problems, and were selected according to their ability to walk more than 500 meters independent of support. These patients were reluctant to undergo surgical procedures and, once informed of this study’s purpose, agreed to participate in it. Excluded from the study were: (1) persons with prior leg fractures; (2) persons with other types of arthritis from endocrine disorders or systemic metabolic diseases; (3) patients with any previous knee surgery. All patients had bilaterally medial compartment OA and a high degree of radiographically demonstrable OA stage III or over’ (stage III, 13; stage IV, 4; stage V, 3; see table 1). The side experiencing the most severe symptoms was chosen for this study (right knee, 11; left knee, 9). Clinical efficacy. Clinical assessments were performed each month after the initial G II application at our hospital
Anterior
Arch
parts,
Lateral
Fig 3. (A) Knee extension after application. (B) Knee flexion showing enlarged knee joint space (asterisk) because of the polyaxial hinge allowing valgus unloading (arrows). (C) 3-dimensional movements allowed by the polyaxial hinge.
G II KNEE
Table
1: Radiographic
BRACING
IN OA PATIENTS,
Staging
stage
Condition
I II III IV V
Bony spur only Narrowing of joint space (less than half normal joint space) Narrowing of joint space (more than half normal joint space) Obliteration of joint space or minor bone attrition (lcm), subluxation, or secondary lateral arthrosis
Data from
Sasaki
and Yasuda?,”
outpatient clinic. To evaluate the effects of the G II OA brace alone, additional use of new oral drugs or any other treatment was prohibited from 1 month before the application of the G II OA brace and throughout the trial period. The functional objective efficacy of the orthosis was assessed utilizing the modified knee scoring system of the Japan Orthopaedic Association (JOA) (table 2), which evaluates pain on walking and on climbing up and down stairs. Knee flexion angle was measured with a protractor while performing each of these activities. The subjective efficacy of the orthosis, ie, whether it was satisfactory or unsatisfactory, was assessed by the patient’s personal comments when each patient underwent periodic check-ups in our outpatient clinic. X-ray findings. X-rays were taken with the brace both on and off every 2 months during the la-month study period. Classification of the radiographic stages (table 1) of OA of the knee was done from the anterior posterior roentgenogram taken in the one-foot-standing position by measuring the femoral-tibia1 angle. Quadriceps muscle strength. Quadriceps muscle strength was evaluated using a dynamometer.b The types of measurements it performs are isokinetic, isotonic, and isometric. In our study, isokinetic function was measured. Sample data regarding power, velocity, and angle are computer analyzed. The apparatus allows for a weighted pad to be placed on the patient’s leg between knee and ankle while the patient is wearing the brace. While seated on the machine, the patient’s ankle was fixed to a lever arm which enabled him or her to perform the exercise. The patient was strapped at the hip and upper thigh to restrict the use of other muscles while moving the load. The exercise was repeated a total of three times and the average of these was calculated. The rate of movement of the isokinetic load was set at 30 degrees per second because this was tolerable by elderly patients. A maximum effort of the knee contractions was exerted by each patient. Each extension was performed from 90” to 0” fiexion.
Table
Matsuno
2: Knee Scoring
of the JOA (Modified)
Pain on walking More than 1 km More than 1 km 1 km-500m 500m-IOOm Less than IOOm Walking impossible Standing impossible Pain ascending and descending stairs No pain No pain using handrail Pain using handrail, not with step-by-step walking Pain with step-by-step walking, not with use of handrail Pain with step-by-step walking and handrail use Impossible
Pain
Points
+ + + +
30 25 20 15 10 5 0 25 20 15 10 5 0
Fig 4. (A) Gait score (JOA) significantly .05). (B) Ascending/descending stairs cant improvement (p < ,051.
improved after application (p < score (JOA) also showed signifi-
Center of gravity. A stabilometer,” developed to assess the limb’s equilibrium function objectively recorded the instability of the center of gravity when a patient stood upright. A load sensor beneath each corner of the sensograph’s square base measured how much the center of the body’s gravity varied according to the body’s movements. Both left-right and anteriorposterior directions were measured in centimeters. Data regarding body weight were entered in the machine. The patient’s feet were placed in 15” of external rotation with the medial malleoli 4cm apart. Patients faced forward with eyes fixed on a mark at eye level. When the center of gravity stabilized, the position was defined as zero value. The movement of the center of gravity was determined during 30 seconds of standing. The degree of instability was defined by the maximum amount of movement from the zero value in the anterior-posterior plane and in the medial-lateral plane. Statistical analysis. Quantitative differences between groups were assessed by one-way variance analysis (Duncan’s New Multiple Range test). Normally distributed variables were evaluated using the paired t test; others were evaluated using the Wilcoxon matched-pairs, signed ranks test.
RESULTS There were no withdrawals from brace application throughout the follow-up period. Nineteen patients, through self-assessment, reported relief from pain. All are still using orthoses. One patient noted no relief from pain, but did not experience any exacerbation of pain. There were no aggravations of the contralateral knee symptoms for any patient throughout the observation period. Efficacy of knee function. The JOA knee scores (table 2) significantly improved with application of the orthosis and continued to improve throughout the observation period (12 months). Figure 4A shows the average walking score changed from 18.0 to 21.5 (p < ,051. The score for ascending and descending stairs (fig 4B) also improved from an average 12.8 before brace application to 15.8 after application 01 < .05). No significant change in the range of knee flexion was noted. Radiographic change. Figure 5 indicates the femorotibial angle decreased at 2 months after application of the orthosis in a representative patient with medial compartment OA. Specifically, the femorotibial angle decreased from 185.1” before application of the orthosis to 183.7” (p < .05) with the brace on at the final follow-up after the orthosis had been in use for 12 months (fig 6).
Arch
Phys
Med Rehabil
Vol78,
July
1997
G II KNEE
BRACING
IN OA
PATIENTS,
Matsuno
Fig 5. This patient is a 72-yearold female farmer. IA) Before brace application, the deletion of the medial joint space was observed. Just after application of the orthosis she experienced pain relief and could work. (B) After 2 months of wearing the orthosis, an enlarged medial joint space and a decrease in the femorotibial angle were observed. (Cl Even after removal of the orthosis, this condition remained.
Quadriceps muscle strength. The isokinetic quadriceps muscle strength with the brace on increased from an average of 36.8Nm to 42.8Nm (p < .OS). (fig 7A). One patient showed a very marked increase from an initial 10 to 1OONm after brace application. A slight decrease in muscle strength was exhibited in only three patients. As shown in figure 7B, the increase in muscle strength was found during the full range of knee motion. In addition, the peak in muscle strength related to the range of motion changed from 40” knee flexion without applying the orthosis to 45” with its application. and right-left Center of gravity. Forward-backward movement in the center of gravity showed a tendency to decrease after brace application, but the change in the average forward-backward movement was not statistically significant. In 7 patients this movement increased, in 11 it remained the same, and in 2 it decreased. However, the average lateral movement decreased significantly with brace application (17.5cm before vs. 15.7cm after). In 1 this movement increased, in 18 it decreased, and in 1 it remained the same. This change reveals that the total movement of the center of gravity decreased because of improvement in the lateral stability of the knee (fig 8).
of arthritic changes or mechanical data were provided in either report. Pain improvement ratio using the TVS brace was 78%. Sasaki and Yasuda,‘,” in their study using a wedged insole, reported 70% improvement in early stage OA and 40% in advanced OA. The Smithi study, in which individually designed braces were used, reported that 75% of its successful users exhibited overall pain reduction. Recently, Horlick and Loomer15 tested the efficacy of G II orthosis valgus bracing in patients with medial compartment OA of the knee. They reported an 82% success rate for pain relief with the brace in valgus. The reason for pain reduction was not analyzed, but we believe that the reason changes were not found in the femorotibial angle was the shorter period (6 weeks) of bracing in the same position. We observed that application of the orthosis increased the knee scores, reflecting a correlation between the degree of pain and function. In view of our findings, two possible factors could have induced this pain-relieving effect. First, the decrease in the center of gravity range caused by a reduction in lateral swing might have improved knee stability, thereby decreasing the load on the medial compartment. A second pain-relieving factor could have been the increase in quadriceps muscle
DISCUSSION The surgical treatment of patients with severe OA of the knee usually produces excellent results.” Because of health problems, however, some patients are not good surgical candidates. Wedged insole treatment,‘.” by reducing the load on the medial joint surface, is effective for the conservative treatment of early medial OA of the knee, but not for severe OA. We observed in this study that bracing of late stage medial OA of the knee resulted in decreased pain, improved functioning in the activities of daily life, increased quadriceps muscle strength, and stabilization of the knee. Knee bracing has been used specifically for prophylaxis, rehabilitation, or functional treatment of sports-related injuries,5 Only a few studies, however, have been performed using such bracing on patients with OA of the knee. Cousins and Foort” observed increased speed in walking and pain relief with bracing of arthritic knees. Jawad and Goodwill” reported pain reduction in OA and rheumatoid arthritis patients-fitted with a telescopic varus/valgus support (TVS), but no specific information regarding the extent
Arch
Phys
Med Rehabil
Vol78,
July
1997
Avg. 185,
before application Fig 6. Femorotibial < .051.
angle
decreased
after application after
brace
( 12 months)
application
(p
G II KNEE
BRACING
IN OA
749
PATIENTS,
VW, Avg. 36.8 NT,,
Fig 7. (A) Quadriceps muscle strength increased after application fp < .05). (B) Isokinetic-tracing from a 72-year-old woman. This figure indicates an increase in muscle strength and maximum muscle strength point after orthosis application. These data were taken just after orthosis application.
Avg. 42.8 urn
I
I
A
no application
application
strength as either a cause or consequence of the improved stability of the knee. This enhanced muscle power can have a positive effect in that there is less pain from activity, and a patient has more endurance. One interesting observation was the decrease in the femorotibia1 angle. This reduction is possibly related to the improvement in knee stability. The femorotibial angle reduction could prove to be useful before total knee replacements by facilitating the operative procedure and the amount of distal femoral osteotomy. Controlled trials over a longer time could better evaluate this potential beneficial effect. This trial was the first clinical study using the G II brace with OA patients, and was not a double-blind study because it was initially unknown whether or not it would prove effective. However, the trial revealed sufficient data warranting further research. In conclusion, knee orthosis treatment for severe medial OA of the knee can cause symptomatic relief and mechanical improvement of knee function. This conservative treatment might be beneficial for knee OA patients who are not good surgical candidates for total knee arthroplasty.
.!. l-
01 A
01 no application application
no application
01
B
no application
application
Fig 8. Change in center of gravity with and without C II orthosis. (A) Anterior-posterior movement. (B) Lateral movement. Lateral movement decreased significantly with brace application (p < ,051.
100
degree
References 1. Heine J. Uber die arthritis deformans. Virchows Archiv 1926;260: 521-663. 2. Kellegan JH, Lawrence JS. Osteoarthrosis and disc degeneration in an urban population. Ann Rheum Dis 1958; 17:388-97. 3. Moskowitz RW, Howell DS, Goldberg VM, Mankin HJ. Osteoarthritis; diagnosis and medical/surgical management. 2nd ed. Philadelphia: Saunders, 1992. 4. Murakami M, Ohta K, Imabori K, editors. Handbook of gerontology. Vol 2. Tokyo; Johokaihatsu Res, 1984 (In Japanese). 5. Goldberg VM. Surgery in osteoarthritis: general conditions. In: Moakowitz RW, Howell DS, Goldberg VM, Mankin HJ, editors, Osteoarthritis; diagnosis and medical/surgical management. 2nd ed. Philadelphia: Saunders, 199253543. 6. Goldman L, Caldera DL, Nussbaum SR, Southwick FS, Krogstad D, Murray B: et al. Multifactorial index of cardiac risk in noncardiac surgical procedure. N Engl J Med 1977;297:845-50. 7. Cohen MM, Duncan PG, Tate RB. Does anesthesia contribute to operative mortality? JAMA 1988;260:2859-63. 8. Tiret L, Desmonth JM, Hatton F, Vourch G. Complication associated with anesthesia: a prospective survey in France. Can Anaesth Sot J 1986;33:336-44. 9. Sasaki T, Yasuda K. Clinical evaluation of the treatment of osteoarthritic knees using a newly designed wedged insole. Clin Orthop 1987:221:181-7. 10. Yasuda K, Sasaki T. The mechanics of treatment of the osteoarthritic knee with a wedged insole. Clin Orthop 1987; 215: 162-72. 11. Rosenberg AG, Barden RM, Galante JO. Cemented and ingrowth fixation of the Miller-Galante prosthesis. Clinical and roentgenographic comparison after three- to six-year follow-up studies. Clin Orthop 1990;260:71-9. 12. Cousins S, Foort J. An orthosis for medial or lateral stabilization of arthritic knees. Orthot Prostet 1975;29:21-6. 13. Jawad ASM, Goodwill CJ. TVS brace in patients with rheumatoid arthritis or osteoarthritis of the knee. Br J Rheumatol 1985;25:416-7. 14. Smith EM, Juvinall RC, Core11 EB, Nyober V. Bracing the unstable arthritic knee. Arch Phys Med Rehabil 1970;51:22-9. 15. Horlick S, Loomer R. Valgus knee bracing for medial gonarthrosis. Clin J Sport Med. 1993;3:251-5. 16. Eloranta V, Komi PV. Postural effects on the function of the quadriceps femoris muscle under concentric contraction. Electromyogr Clin Neurophysiol 1981;21:555-67. 17. Portnoy H, Morin F. Electromyographic study of postural muscle in various positions and movement. Am J Physiol 1956; 186:122-6. Suppliers a. Generation II Orthotics, Ltd, 11091 Hammersmith Gate, Richmond, British Columbia, V7A 5E6 Canada. b. KIN-SOO-HX; Japan Chattanooga Co., 3968 Uruido Hasuda, City Saitama Pref, Japan. c. IG06 sensograph; San-Ei Co, 3-42-6 Hongo, Bunkyo-ku, Tokyo, Japan.
Arch
Phys Med
Rehabil
Vol78,
July
1997
Generation II Knee Bracing for Severe Medial Compartment Osteoarthritis of the Knee Hiroaki Matsuno,
MD, PhD, Ken Morris Kadowaki, MD, PhD, Haruo Tsuji, MD, PhD
ABSTRACT. Matsuno H, Kadowaki KM, Tsuji H. Generation II knee bracing for severe medial compartment osteoarthritis of the knee. Arch Phys Med Rehabil 1997;78: 745-9. Objective: To investigate the clinical efficacy of the Generation II (G II) knee brace, a newly developed knee orthosis, on patients experiencing severe medial compartment osteoarthritis (OA) of the knee. Design: Case series. Setting: A national medical and pharmaceutical hospital in Japan. Patients: Twenty primary OA subjects (excluding those with secondary OA), all older than 55 years of age and experiencing only knee joint problems, were selected according to their ability to walk more than 500 meters independent of support. These patients had arthritis in both knees and no less than one half of normal joint space remaining as revealed by roentgenogram studies. The more severely affected side was selected for bracing. Interventions: For 12 months, each patient wore a G II knee brace on the affected knee on a daily basis, removing it only at night. To evaluate the effects of G II OA brace alone, additional use of new oral drugs or any other treatment was prohibited from 1 month before application of the G II OA brace and throughout the trial period. Main Outcome Measures: Clinical efficacy was evaluated using the Japan Orthopaedic Association’s knee scoring system. X-ray evaluation was performed with patients standing on one leg. A dynamometer was used to evaluate isokinetic quadriceps muscle strength. The center of gravity was measured using an X-Y recording. Clinical evaluation was performed every 2 months thereafter. Final evaluation was at 12 months. Results: Nineteen of the 20 patients answered that they experienced significant pain relief. Knee pain scores on walking increased from 18.0 to 21.5 and on ascending and descending stairs increased from 12.8 to 15.8. The femorotibial angle decreased in 12 of the patients, and the mean angle decreased from 185.1” before application to 183.7” with the brace on at the final observation period. In addition, isokinetic quadriceps muscle strength increased from an average of 36.8Nm to 428Nm for all patients. In 17 patients, quadriceps muscle strength increased, while it decreased in 2 and remained the From the Department of Orthopaedic Surgery, Toyama Medical and Pharmaceutical University, Toyama City, Japan. Submitted for publication July 19, 1996. Accepted in revised form January 10, 1997. Supported by a grant from Generation II USA, Inc. No commercial party having a direct or indirect interest in the subject matter of this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated. Reprint requests to Hiroaki Matsuno MD, PhD, Department of Orthopaedic Surgery, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama City, Japan. 0 1997 bv the American Conmess of Rehabilitation Medicine and the American Academy oi Physical Medicine-and Rehabilitation 0003-9993/97/7807-4116$3.00/O
same in 1. Finally, lateral movement of the center of gravity decreased compared with before G II application in all patients. Conclusion: G II bracing is a beneficial treatment for severe medial OA of the knee. 0 1997 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation STEOARTHRITIS (OA) of the knee is not an uncommon in a person of advanced age.’ From his study of 01,002disease dissection cases,Heine’ concluded that OA occurred most commonly in knee joints; moreover, more than 90% of the OAs occurred in persons 60 years of age or older. This study correlates with the clinical and roentgenologic assessmentof Kellgren and Lawrence,* wherein more than 80% of persons 55 years old or older experienced OA. In addition, many other reports3 conclude mat OA is strongly influenced by age and, accordingly, the occurrence increases linearly. At present, the Japanese health care system is facing a rapid increase in the number of aged persons. In 1965, 9.7% of the population was older than 60; in 1980, 12.9% were older than 60; by 1990, 17.6% had reached this age.4 It is well known that this population is at a much higher risk for surgical and anesthetic procedures.5s8Goldberg4 reported that the operative risk to aged OA patients was related to their declining general medical condition. In particular, such patients experienced more cardiovascular and respiratory diseases.Specific to Japan for example, cardiovascular diseaseis 3.5 times higher in persons older than 55.4 Therefore, to avoid surgery whenever possible, an alternative procedure would be useful. A wedge insole orthosis has already been used for OA patients in Japan. That treatment modality however, has been shown to be effective only in early-stage OA; severe OA is not affected. 9,10Thus, a more effective therapy is needed. Further, as the demographics discussedabove change, the number of patients who will be good candidates for bracing will also increase. The Generation II (G II) brace was designed in Canada by Generation II Orthotics Ltd.” The company developed a polyaxially hinged brace that allows the normal motion of a patient’s knee. The hinge mechanism has been adapted to an OA brace which is designed to provide relief for the pain associated with OA (fig 1). The brace is custom-made and consists of an ultrahigh molecular weight (UHMW) polyethylene thigh shell connected to a UHMW polyethylene calf shell via the polyaxial hinge on the medial side. The other key feature is a nylon tensioning strap on the lateral side. In Japan, the average size is 45cm in length and the weight is 700 grams (fig 2). The distinctive feature of this brace is the polyaxial hinge, which is used to enlarge the joint space at, for example, the medial femorotibial compartment of the knee (fig 3). When the brace has been applied, and the knee is flexed to 60”, the hinge is bent into valgus for the sagittal plane of the patient’s knee extension condition, allowing the knee joint space to enlarge. As the patient flexes his or her knee to its full 130”, the hinge continues to bend into valgus until the angle formed reaches 30” in the sagittal knee extension
Arch
Phys
Med Rehabil
Vol78,
July
1997
746
G II KNEE
BRACING
IN OA
PATIENTS,
Matsuno
Fig 2. Structure,
Fig 1. The G II brace consists of both a thigh and a calf strap that connected by a diagonal strap. (A) On the medial side of the knee single, polyaxial hinge. (B) Lateral view.
are is a
condition. This allows more normalized conditions when the knee is flexed and thus decreases pain levels. If the medial joint space in OA patients could be enlarged using this orthosis, their painful symptoms could be eliminated or decreased. The purpose of this study was to examine the effect of this G II brace on patients suffering from OA of the knee.
PATIENTS AND METHODS Patients. The patients were 4 men and 16 women 58 to 84 years (average 76.6). All experienced only
aged knee
Phys Med
Rehabil
Vol 78, July
1997
and material
of the G II OA brace.
joint problems, and were selected according to their ability to walk more than 500 meters independent of support. These patients were reluctant to undergo surgical procedures and, once informed of this study’s purpose, agreed to participate in it. Excluded from the study were: (1) persons with prior leg fractures; (2) persons with other types of arthritis from endocrine disorders or systemic metabolic diseases; (3) patients with any previous knee surgery. All patients had bilaterally medial compartment OA and a high degree of radiographically demonstrable OA stage III or over’ (stage III, 13; stage IV, 4; stage V, 3; see table 1). The side experiencing the most severe symptoms was chosen for this study (right knee, 11; left knee, 9). Clinical efficacy. Clinical assessments were performed each month after the initial G II application at our hospital
Anterior
Arch
parts,
Lateral
Fig 3. (A) Knee extension after application. (B) Knee flexion showing enlarged knee joint space (asterisk) because of the polyaxial hinge allowing valgus unloading (arrows). (C) 3-dimensional movements allowed by the polyaxial hinge.
G II KNEE
Table
1: Radiographic
BRACING
IN OA PATIENTS,
Staging
stage
Condition
I II III IV V
Bony spur only Narrowing of joint space (less than half normal joint space) Narrowing of joint space (more than half normal joint space) Obliteration of joint space or minor bone attrition (
Data from
Sasaki
and Yasuda?,”
outpatient clinic. To evaluate the effects of the G II OA brace alone, additional use of new oral drugs or any other treatment was prohibited from 1 month before the application of the G II OA brace and throughout the trial period. The functional objective efficacy of the orthosis was assessed utilizing the modified knee scoring system of the Japan Orthopaedic Association (JOA) (table 2), which evaluates pain on walking and on climbing up and down stairs. Knee flexion angle was measured with a protractor while performing each of these activities. The subjective efficacy of the orthosis, ie, whether it was satisfactory or unsatisfactory, was assessed by the patient’s personal comments when each patient underwent periodic check-ups in our outpatient clinic. X-ray findings. X-rays were taken with the brace both on and off every 2 months during the la-month study period. Classification of the radiographic stages (table 1) of OA of the knee was done from the anterior posterior roentgenogram taken in the one-foot-standing position by measuring the femoral-tibia1 angle. Quadriceps muscle strength. Quadriceps muscle strength was evaluated using a dynamometer.b The types of measurements it performs are isokinetic, isotonic, and isometric. In our study, isokinetic function was measured. Sample data regarding power, velocity, and angle are computer analyzed. The apparatus allows for a weighted pad to be placed on the patient’s leg between knee and ankle while the patient is wearing the brace. While seated on the machine, the patient’s ankle was fixed to a lever arm which enabled him or her to perform the exercise. The patient was strapped at the hip and upper thigh to restrict the use of other muscles while moving the load. The exercise was repeated a total of three times and the average of these was calculated. The rate of movement of the isokinetic load was set at 30 degrees per second because this was tolerable by elderly patients. A maximum effort of the knee contractions was exerted by each patient. Each extension was performed from 90” to 0” fiexion.
Table
Matsuno
2: Knee Scoring
of the JOA (Modified)
Pain on walking More than 1 km More than 1 km 1 km-500m 500m-IOOm Less than IOOm Walking impossible Standing impossible Pain ascending and descending stairs No pain No pain using handrail Pain using handrail, not with step-by-step walking Pain with step-by-step walking, not with use of handrail Pain with step-by-step walking and handrail use Impossible
Pain
Points
+ + + +
30 25 20 15 10 5 0 25 20 15 10 5 0
Fig 4. (A) Gait score (JOA) significantly .05). (B) Ascending/descending stairs cant improvement (p < ,051.
improved after application (p < score (JOA) also showed signifi-
Center of gravity. A stabilometer,” developed to assess the limb’s equilibrium function objectively recorded the instability of the center of gravity when a patient stood upright. A load sensor beneath each corner of the sensograph’s square base measured how much the center of the body’s gravity varied according to the body’s movements. Both left-right and anteriorposterior directions were measured in centimeters. Data regarding body weight were entered in the machine. The patient’s feet were placed in 15” of external rotation with the medial malleoli 4cm apart. Patients faced forward with eyes fixed on a mark at eye level. When the center of gravity stabilized, the position was defined as zero value. The movement of the center of gravity was determined during 30 seconds of standing. The degree of instability was defined by the maximum amount of movement from the zero value in the anterior-posterior plane and in the medial-lateral plane. Statistical analysis. Quantitative differences between groups were assessed by one-way variance analysis (Duncan’s New Multiple Range test). Normally distributed variables were evaluated using the paired t test; others were evaluated using the Wilcoxon matched-pairs, signed ranks test.
RESULTS There were no withdrawals from brace application throughout the follow-up period. Nineteen patients, through self-assessment, reported relief from pain. All are still using orthoses. One patient noted no relief from pain, but did not experience any exacerbation of pain. There were no aggravations of the contralateral knee symptoms for any patient throughout the observation period. Efficacy of knee function. The JOA knee scores (table 2) significantly improved with application of the orthosis and continued to improve throughout the observation period (12 months). Figure 4A shows the average walking score changed from 18.0 to 21.5 (p < ,051. The score for ascending and descending stairs (fig 4B) also improved from an average 12.8 before brace application to 15.8 after application 01 < .05). No significant change in the range of knee flexion was noted. Radiographic change. Figure 5 indicates the femorotibial angle decreased at 2 months after application of the orthosis in a representative patient with medial compartment OA. Specifically, the femorotibial angle decreased from 185.1” before application of the orthosis to 183.7” (p < .05) with the brace on at the final follow-up after the orthosis had been in use for 12 months (fig 6).
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G II KNEE
BRACING
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PATIENTS,
Matsuno
Fig 5. This patient is a 72-yearold female farmer. IA) Before brace application, the deletion of the medial joint space was observed. Just after application of the orthosis she experienced pain relief and could work. (B) After 2 months of wearing the orthosis, an enlarged medial joint space and a decrease in the femorotibial angle were observed. (Cl Even after removal of the orthosis, this condition remained.
Quadriceps muscle strength. The isokinetic quadriceps muscle strength with the brace on increased from an average of 36.8Nm to 42.8Nm (p < .OS). (fig 7A). One patient showed a very marked increase from an initial 10 to 1OONm after brace application. A slight decrease in muscle strength was exhibited in only three patients. As shown in figure 7B, the increase in muscle strength was found during the full range of knee motion. In addition, the peak in muscle strength related to the range of motion changed from 40” knee flexion without applying the orthosis to 45” with its application. and right-left Center of gravity. Forward-backward movement in the center of gravity showed a tendency to decrease after brace application, but the change in the average forward-backward movement was not statistically significant. In 7 patients this movement increased, in 11 it remained the same, and in 2 it decreased. However, the average lateral movement decreased significantly with brace application (17.5cm before vs. 15.7cm after). In 1 this movement increased, in 18 it decreased, and in 1 it remained the same. This change reveals that the total movement of the center of gravity decreased because of improvement in the lateral stability of the knee (fig 8).
of arthritic changes or mechanical data were provided in either report. Pain improvement ratio using the TVS brace was 78%. Sasaki and Yasuda,‘,” in their study using a wedged insole, reported 70% improvement in early stage OA and 40% in advanced OA. The Smithi study, in which individually designed braces were used, reported that 75% of its successful users exhibited overall pain reduction. Recently, Horlick and Loomer15 tested the efficacy of G II orthosis valgus bracing in patients with medial compartment OA of the knee. They reported an 82% success rate for pain relief with the brace in valgus. The reason for pain reduction was not analyzed, but we believe that the reason changes were not found in the femorotibial angle was the shorter period (6 weeks) of bracing in the same position. We observed that application of the orthosis increased the knee scores, reflecting a correlation between the degree of pain and function. In view of our findings, two possible factors could have induced this pain-relieving effect. First, the decrease in the center of gravity range caused by a reduction in lateral swing might have improved knee stability, thereby decreasing the load on the medial compartment. A second pain-relieving factor could have been the increase in quadriceps muscle
DISCUSSION The surgical treatment of patients with severe OA of the knee usually produces excellent results.” Because of health problems, however, some patients are not good surgical candidates. Wedged insole treatment,‘.” by reducing the load on the medial joint surface, is effective for the conservative treatment of early medial OA of the knee, but not for severe OA. We observed in this study that bracing of late stage medial OA of the knee resulted in decreased pain, improved functioning in the activities of daily life, increased quadriceps muscle strength, and stabilization of the knee. Knee bracing has been used specifically for prophylaxis, rehabilitation, or functional treatment of sports-related injuries,5 Only a few studies, however, have been performed using such bracing on patients with OA of the knee. Cousins and Foort” observed increased speed in walking and pain relief with bracing of arthritic knees. Jawad and Goodwill” reported pain reduction in OA and rheumatoid arthritis patients-fitted with a telescopic varus/valgus support (TVS), but no specific information regarding the extent
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1997
Avg. 185,
before application Fig 6. Femorotibial < .051.
angle
decreased
after application after
brace
( 12 months)
application
(p
G II KNEE
BRACING
IN OA
749
PATIENTS,
VW, Avg. 36.8 NT,,
Fig 7. (A) Quadriceps muscle strength increased after application fp < .05). (B) Isokinetic-tracing from a 72-year-old woman. This figure indicates an increase in muscle strength and maximum muscle strength point after orthosis application. These data were taken just after orthosis application.
Avg. 42.8 urn
I
I
A
no application
application
strength as either a cause or consequence of the improved stability of the knee. This enhanced muscle power can have a positive effect in that there is less pain from activity, and a patient has more endurance. One interesting observation was the decrease in the femorotibia1 angle. This reduction is possibly related to the improvement in knee stability. The femorotibial angle reduction could prove to be useful before total knee replacements by facilitating the operative procedure and the amount of distal femoral osteotomy. Controlled trials over a longer time could better evaluate this potential beneficial effect. This trial was the first clinical study using the G II brace with OA patients, and was not a double-blind study because it was initially unknown whether or not it would prove effective. However, the trial revealed sufficient data warranting further research. In conclusion, knee orthosis treatment for severe medial OA of the knee can cause symptomatic relief and mechanical improvement of knee function. This conservative treatment might be beneficial for knee OA patients who are not good surgical candidates for total knee arthroplasty.
.!. l-
01 A
01 no application application
no application
01
B
no application
application
Fig 8. Change in center of gravity with and without C II orthosis. (A) Anterior-posterior movement. (B) Lateral movement. Lateral movement decreased significantly with brace application (p < ,051.
100
degree
References 1. Heine J. Uber die arthritis deformans. Virchows Archiv 1926;260: 521-663. 2. Kellegan JH, Lawrence JS. Osteoarthrosis and disc degeneration in an urban population. Ann Rheum Dis 1958; 17:388-97. 3. Moskowitz RW, Howell DS, Goldberg VM, Mankin HJ. Osteoarthritis; diagnosis and medical/surgical management. 2nd ed. Philadelphia: Saunders, 1992. 4. Murakami M, Ohta K, Imabori K, editors. Handbook of gerontology. Vol 2. Tokyo; Johokaihatsu Res, 1984 (In Japanese). 5. Goldberg VM. Surgery in osteoarthritis: general conditions. In: Moakowitz RW, Howell DS, Goldberg VM, Mankin HJ, editors, Osteoarthritis; diagnosis and medical/surgical management. 2nd ed. Philadelphia: Saunders, 199253543. 6. Goldman L, Caldera DL, Nussbaum SR, Southwick FS, Krogstad D, Murray B: et al. Multifactorial index of cardiac risk in noncardiac surgical procedure. N Engl J Med 1977;297:845-50. 7. Cohen MM, Duncan PG, Tate RB. Does anesthesia contribute to operative mortality? JAMA 1988;260:2859-63. 8. Tiret L, Desmonth JM, Hatton F, Vourch G. Complication associated with anesthesia: a prospective survey in France. Can Anaesth Sot J 1986;33:336-44. 9. Sasaki T, Yasuda K. Clinical evaluation of the treatment of osteoarthritic knees using a newly designed wedged insole. Clin Orthop 1987:221:181-7. 10. Yasuda K, Sasaki T. The mechanics of treatment of the osteoarthritic knee with a wedged insole. Clin Orthop 1987; 215: 162-72. 11. Rosenberg AG, Barden RM, Galante JO. Cemented and ingrowth fixation of the Miller-Galante prosthesis. Clinical and roentgenographic comparison after three- to six-year follow-up studies. Clin Orthop 1990;260:71-9. 12. Cousins S, Foort J. An orthosis for medial or lateral stabilization of arthritic knees. Orthot Prostet 1975;29:21-6. 13. Jawad ASM, Goodwill CJ. TVS brace in patients with rheumatoid arthritis or osteoarthritis of the knee. Br J Rheumatol 1985;25:416-7. 14. Smith EM, Juvinall RC, Core11 EB, Nyober V. Bracing the unstable arthritic knee. Arch Phys Med Rehabil 1970;51:22-9. 15. Horlick S, Loomer R. Valgus knee bracing for medial gonarthrosis. Clin J Sport Med. 1993;3:251-5. 16. Eloranta V, Komi PV. Postural effects on the function of the quadriceps femoris muscle under concentric contraction. Electromyogr Clin Neurophysiol 1981;21:555-67. 17. Portnoy H, Morin F. Electromyographic study of postural muscle in various positions and movement. Am J Physiol 1956; 186:122-6. Suppliers a. Generation II Orthotics, Ltd, 11091 Hammersmith Gate, Richmond, British Columbia, V7A 5E6 Canada. b. KIN-SOO-HX; Japan Chattanooga Co., 3968 Uruido Hasuda, City Saitama Pref, Japan. c. IG06 sensograph; San-Ei Co, 3-42-6 Hongo, Bunkyo-ku, Tokyo, Japan.
Arch
Phys Med
Rehabil
Vol78,
July
1997