ORIGINAL COMMUNICATIONS Endoscopic release of the carpal tunnel: A randomized prospective multicenter study A 10-center randomized prospective multicenter study of endoscopic release of the carpal tunnel was carried out. Surgery was performed with a new device for transecting the transverse carpal ligament while control hands were treated with conventional open surgery. There were 122 patients in the study; 25 had carpal tunnel surgery on both hands and 97 had surgery on one hand. Of the surgical procedures, 65 were in the control group and 82 were in the device group. The endoscopic device was coupled to a fiberoptic light and a video camera. A trigger-activated blade was used to incise the transverse carpal ligament. After surgery, the best predictors of return to work and to activities of daily living were strength and tenderness variables. For patients in the device group with one affected hand, the median time for return to work was 21111 days less than that for the control group . Two patients treated with the endoscopicdevice required reoperation by open surgical decompression; only one of these had incomplete release with the device. Two patients in the device group experienced transient ulnar neurapraxia. (J HAND SURG 1992;17A:987-95.)
John M . Agee, MD, Sacramento, Calif , H. Relton McCarroll , Jr. , MD, San Francisco, Calif., Richard D. Tortosa , MD, Yuba City, Calif., Donald A. Berry, PhD, Durham , N.C ., Robert M. Szabo, MD, Sacramento, Calif., and Clayton A . Peimer, MD, Buffalo , N .Y.
Carpal tunnel syndrome is the most commonly diagnosed peripheral entrapment neuropathy. I The technical aspects of its surgical care are controversial? and varied. I , 3 Although conventional open surgical release of the carpal tunnel predictably relieves the symptoms of median nerve compression , it is frequently associated with postoperative pain , tenderness , and weakness that delay the patient's return to activities of daily living (ADL) and emplo yment. In contrast to the open surgical technique , som e surgeons have advocated a transverse skin incision at the
Supported in part by the 3M Orth opedic Products Division, 51. Paul , Minn. Received for publicat ion OCI. 24, 1991; accepted in revised form May 20 , 1992. One or more of the authors have received or will receive benefits for personal or professional use from a commercial party related directly or indirectl y to the subject of this article. Reprint requests : John M. Agee , MD, Director, Hand Biomechanics Laboratory, Inc" 77 Scripps Dr. , Suite 101, Sacramento, CA 95825 .
3/1/38959
wrisr' combined with a blind surgical release of a transverse carpal ligament by means of knives, scissors, and special instruments. It is our hypothesis that a surgical approach that combines endoscopic visualization of the transverse carpal ligament with a limited surgical incision will offer the benefits of decreased postoperative morbidity without unacceptable risk to the patient.
Materials and methods Endoscopic device. The endoscopic device (3M Orthopedic Products Division , St. Paul, Minn.) and the surgical technique were developed at the Hand Biomechanic s Laboratory in Sacramento, Calif. The design of the device was developed in concert with the surgical technique," with each evolving through the use of a series of prototypes on fresh cadaver spe cimens. The device has a pistol grip handp iece with an integral trigger mechanism from which extends a blade assembly desig ned in size and shape to be inserted down the length of the carpal tunnel. A rectangular window on the flat upper surface near the tip of the blade assembly permits viewing of the transverse carpal ligament through an endoscope positioned just proximal to the
THE JOURNAL OF HAND SURGERY
987
988
Agee et al,
Fig. 1. The probe is inserted through an incision in forearm fascia. All instruments and the device follow the ring finger ray.
window. A trigger-actuated retractable blade immediately distal to the window elevates 3.5 mm above the surface of the blade assembly. The flat upper surface of the blade assembly is designed to avoid injury to the median nerve and digital flexor tendons when the window is snugly applied to the deep side of the ligament. A video camera and a fiberoptic light source coupled to the endoscope provide direct viewing and illumination similar to those provided by other endoscopic/ athroscopic equipment. Surgical technique. With the use of tourniquet control and regional block or general anesthesia, a 2 em skin incision is placed in the wrist flexion crease between the flexor carpi radialis and flexi carpi ulnaris tendons. A spreading subcutaneous dissection protects the underlying palmar cutaneous nerve. A probe inserted through a distally based V-shaped incision in the forearm fascia helps define a proximal-to-distal path down the palmar-ulnar aspect of the carpal tunnel. With the device aimed at the ring finger and with the wrist in extension, the blade assembly of the device is inserted along the same path (Fig. 1). Through the window near the tip of the device's blade assembly, a strip of transverse carpal ligament that is
The Journal of HAND SURGERY
free of all other structures is visualized. Once the distal edge of the ligament is clearly identified and the ulnar position and ring finger aim are checked, the trigger is pulled to elevate the blade in a triangular area defined by the ulnar half of the distal edge of the transverse carpal ligament, the ulnar border of the median nerve and/ or its digital branches, and the proximal edge of the superficial palmar arch (Fig. 2). Application of upward pressure to hold the window against the deep side of the ligament as the device is gently withdrawn excludes flexor tendons and the median nerve during incision of the transverse carpal ligament (Fig. 3). Additional passes may be necessary for complete release of the transverse carpal ligament, with endoscopic control permitting visualization of its cut edges. Study design. A ten-center study compared conventional open primary carpal tunnel release with closed endoscope-assisted release. The study design was reviewed and approved by each center's institutional review board, and informed consent was obtained from each patient. Patients were required to meet entry criteria designed to identify idiopathic carpal tunnel syndrome supported by abnormal nerve studies but normal electromyograms. Patient inclusion/ exclusion criteria included the absence of generalized peripheral neuropathy as well as diabetes mellitus or thyroid disease, anatomic abnormalities of the wrist and hand (including previous displaced fractures), inflammatory joint diseases, a history of median nerve injury from trauma (including contusion, fracture of the distal radius or wrist joint, etc.), previous surgery on the wrist, vasospastic disorders such as Raynaud's disease or sympathetic dystrophies and their equivalents, psychiatric disorders, chronic renal disease requiring dialysis, previous carpal tunnel release, thenar weakness sufficient to require tendon transfer to support thumb opposition at the time of carpal tunnel release (Camitz or other), and any other surgery required at the time of carpal tunnel release. There were 122 patients in the study; 25 had carpal tunnel surgery on both hands and 97 had surgery on one hand. Thus a total of 147 carpal tunnel procedures were performed. Of these, 82 were in the device group and 65 were in the conventional open surgical control group. Of the patients with unilateral procedures, 79 were workers; of these, 49 were in the device group and 30 were in the control group. The only significant difference between the two treatment groups was the use of diuretics during preoperative treatment of the carpal tunnel syndrome in 2 of 82 patients in the device group and 7 of 65 patients in the control group. Some differences were expected on the basis of chance alone; however, these differences should not have had a material effect on the results.
Vol. 17A, No.6 November 1992
Endoscopic relase of carpal funnel
989
Blade Assembly
Fig. 2. Safe zone of blade elevation. The safe zone is within a triangle defined by the ulnar half of the distal edge of the transverse carpal ligament (a), the ulnar border of the median nerve, i.e., its common digital branch (b), and the ulnar proximal margin of the superficial palmar arch (c) .
....
Fig. 3. Transverse carpal ligament incision on withdrawal of device.
In patients who had bilateral carpal tunnel syndrome, each hand was operated on in a separate procedure. In the early part of the study, the first hand to be treated surgically was randomized into the control or device groups. Frequently, those patients who had the first carpal tunnel release performed endoscopically refused to have the other hand treated with the conventional open surgical approach. Later in the study, patients with bilateral carpal tunnel syndrome had the control surgery first, followed by surgery with the endoscopic device on the opposite hand. Clinical examination. Before surgery, the following tests were performed on the affected and unaffected hands: grip strength with Jamar dynamometer readings at five settings; pinch strength, both lateral/key and
pulp; Semmes-Weinstein monofilament sensory mapping; Phalen's wrist flexion test; Tinel's test at the carpal tunnel; and manual motor testing, with grades 0 through 5, for thumb abduction. In addition, all patients had preoperative wrist x-ray films, including a carpal tunnel view (normal films were required for patient participation). All patients were questioned about any drug therapy they had received in the 4 weeks preceding entry into the study. At postoperative weeks 1, 2, 3, 6, 9, 13, and 26, the following data were collected: employment status, return of hand use for ADL, postoperative symptoms (same as preoperative), and clinical examination data for comparison with the preoperative data (grip and pinch measurements, monofilament sensory examina-
990
Agee et al.
tion, motor testing of thenar muscles, etc.) Grip strength was never tested at week 1 because of wound healing. In addition, scar tenderness and radial and ulnar pillar tenderness were graded from 0 to 4 (none to very tender), and a record of medication use was completed. Data analysis. For evaluation of the effect of surgery within each treatment group at each visit, the hypothesis of no change from preoperative evaluation was tested. For quantitative variables, such as percentage change from preoperative values, paired t tests" were used. For categorical variables, such as normal! abnormal, McNemar's test" was used. Retired persons, housewives, and persons who had bilateral surgical procedures were excluded from analysis of times for return to work. In the comparison of times of return to ADL, patients who had bilateral surgery were included with those who had unilateral surgery. The data for return to ADL by the two treatment groups of bilateral surgery patients also were compared separately by the Wilcoxon two-sample rank test. 6 The Kaplan-Meier method? was used to estimate median times of return to work and to ADL. Treatment groups were compared on the basis of times of return to work and to ADL by means of a survival analysis version of the Wilcoxon test. 8 Results Strength, sensory, and motor testing. Hands in both treatment groups were weaker in the early postoperative period than they were before surgery. Hands in both' groups became stronger with time. Patients in the device group returned to preoperative or greater strength more quickly than those in the control group (p < 0.05, Table I). There was no difference in sensory and motor (thenar) test results between the device and control groups (Table II). Within both treatment groups, sensory test results improved (p < 0.05) at week 2 as compared with preoperative measurements, except those for the small finger, which showed little if any subsequent improvement. Motor tests showed continual improvement in both groups, with both groups eventually exceeding preoperative levels. Phalen's and Tinel's test scores improved dramatically and similarly in the two groups (p < 0.05, Table III). Patient assessments. As shown in Table IV, the percentage of patients with pain, tingling, weakness, and numbness decreased over the course of the study within both treatment groups (p < 0.05). However, one of four patients in each group was still reporting some pain 6 months after surgery. Similarly, 6 months after surgery, about one patient in eight reported tingling,
The Journal of HAND SURGERY
one in three was reporting weakness, and one in six was reporting numbness. Table V shows that patients in the device group experienced less scar tenderness throughout the study than did controls, with the difference being statistically significant at weeks 1,2,3, and 9. The device group also experienced less radial pillar tenderness 3 and 9 weeks after surgery, and less ulnar pillar tenderness 1 week after surgery, while tenderness reported during the remaining visits was comparable in the two groups. Median times of return to work and to ADL. The 50% line in Fig. 4 shows that the median time for patients with unilateral surgery to return to work was 25 days for the device group and 46.5 days for the control group (p < 0.01). Patients with workers' compensation took much longer to return to work than did patients without workers' compensation. The median time to return to work for patients on workers' compensation was 71 days in the device group and 78 days in the control group (Table VI). Among patients not receiving workers' compensation, the device group had a greater advantage in time for return to work over the control group (p < 0.01) than was observed when all patients in the two groups were compared. Median time to return to work for unilateral surgery patients without workers' compensation in the device group was 16.5 days as compared to 45.5 days in the control group (Fig. 5 and Table VI). Also, 75% of the patients in the device group had returned to work by 42 days whereas it took 52 days for 75% of the control patients to return to work. (Fig. 5). The median times for return to ADL for all patients, with and without workers' compensation, are shown in Table VI. For the patients without workers' compensation, these times were 5 and 13 days, respectively, for the device and control groups (p < 0.01). Of the 25 patients with bilateral operations, 16 returned to ADL sooner with the device-treated hand than they did with the control hand. The difference was not statistically significant. Center effect. In a multicenter study, there is a possibility that a few centers could influence the results in a given direction whereas other centers could have the opposite effect. When data from each center were examined separately, there was reasonable uniformity in the results across centers, with the direction of the effect being the same for virtually all centers. Complications. TWo patients in the device group had persistent signs and symptoms of carpal tunnel syndrome that required reoperation by conventional open surgery. One patient, with an incomplete release of the proximal extent of the transverse carpal ligament, had complete resolution of symptoms after surgery. The
Vol. 17A, No.6 November 1992
Endoscopic relase of carpal IUIl/Iel
991
Table I. Strength by time since surgery Mean percent changefrom preoperative value Postoperative week Strength measurement" group Jamar grip Device Control Lateral I key pinch Device Control Pulp pinch Device Control Sample sizet Device Control
I NA NA
2
I
6
I
3
I
I
9
/3
I
26 14~
-55
-2U -38
-12 -22
-16§ -32
-211 -19
6
m
14~
21~
-52
-I
3
10
14~
-26 -52
-28
-II
I
10 7t
9 17
1411 17
74 51
74 60
79 57
73 57
72
59
64 48
-33~
-27~
-4
-II§
-4 -14
6t
72
-2
9
55
'Strength was measured in pounds and expressed as percent change from preoperative value. tSample sizes are maxima; for some variables, a small number of observations was missing. *Significant improvement compared with control, p -c 0.001. §Significant improvement compared with control, p
John M . Agee, MD, Sacramento, Calif , H. Relton McCarroll , Jr. , MD, San Francisco, Calif., Richard D. Tortosa , MD, Yuba City, Calif., Donald A. Berry, PhD, Durham , N.C ., Robert M. Szabo, MD, Sacramento, Calif., and Clayton A . Peimer, MD, Buffalo , N .Y.
Carpal tunnel syndrome is the most commonly diagnosed peripheral entrapment neuropathy. I The technical aspects of its surgical care are controversial? and varied. I , 3 Although conventional open surgical release of the carpal tunnel predictably relieves the symptoms of median nerve compression , it is frequently associated with postoperative pain , tenderness , and weakness that delay the patient's return to activities of daily living (ADL) and emplo yment. In contrast to the open surgical technique , som e surgeons have advocated a transverse skin incision at the
Supported in part by the 3M Orth opedic Products Division, 51. Paul , Minn. Received for publicat ion OCI. 24, 1991; accepted in revised form May 20 , 1992. One or more of the authors have received or will receive benefits for personal or professional use from a commercial party related directly or indirectl y to the subject of this article. Reprint requests : John M. Agee , MD, Director, Hand Biomechanics Laboratory, Inc" 77 Scripps Dr. , Suite 101, Sacramento, CA 95825 .
3/1/38959
wrisr' combined with a blind surgical release of a transverse carpal ligament by means of knives, scissors, and special instruments. It is our hypothesis that a surgical approach that combines endoscopic visualization of the transverse carpal ligament with a limited surgical incision will offer the benefits of decreased postoperative morbidity without unacceptable risk to the patient.
Materials and methods Endoscopic device. The endoscopic device (3M Orthopedic Products Division , St. Paul, Minn.) and the surgical technique were developed at the Hand Biomechanic s Laboratory in Sacramento, Calif. The design of the device was developed in concert with the surgical technique," with each evolving through the use of a series of prototypes on fresh cadaver spe cimens. The device has a pistol grip handp iece with an integral trigger mechanism from which extends a blade assembly desig ned in size and shape to be inserted down the length of the carpal tunnel. A rectangular window on the flat upper surface near the tip of the blade assembly permits viewing of the transverse carpal ligament through an endoscope positioned just proximal to the
THE JOURNAL OF HAND SURGERY
987
988
Agee et al,
Fig. 1. The probe is inserted through an incision in forearm fascia. All instruments and the device follow the ring finger ray.
window. A trigger-actuated retractable blade immediately distal to the window elevates 3.5 mm above the surface of the blade assembly. The flat upper surface of the blade assembly is designed to avoid injury to the median nerve and digital flexor tendons when the window is snugly applied to the deep side of the ligament. A video camera and a fiberoptic light source coupled to the endoscope provide direct viewing and illumination similar to those provided by other endoscopic/ athroscopic equipment. Surgical technique. With the use of tourniquet control and regional block or general anesthesia, a 2 em skin incision is placed in the wrist flexion crease between the flexor carpi radialis and flexi carpi ulnaris tendons. A spreading subcutaneous dissection protects the underlying palmar cutaneous nerve. A probe inserted through a distally based V-shaped incision in the forearm fascia helps define a proximal-to-distal path down the palmar-ulnar aspect of the carpal tunnel. With the device aimed at the ring finger and with the wrist in extension, the blade assembly of the device is inserted along the same path (Fig. 1). Through the window near the tip of the device's blade assembly, a strip of transverse carpal ligament that is
The Journal of HAND SURGERY
free of all other structures is visualized. Once the distal edge of the ligament is clearly identified and the ulnar position and ring finger aim are checked, the trigger is pulled to elevate the blade in a triangular area defined by the ulnar half of the distal edge of the transverse carpal ligament, the ulnar border of the median nerve and/ or its digital branches, and the proximal edge of the superficial palmar arch (Fig. 2). Application of upward pressure to hold the window against the deep side of the ligament as the device is gently withdrawn excludes flexor tendons and the median nerve during incision of the transverse carpal ligament (Fig. 3). Additional passes may be necessary for complete release of the transverse carpal ligament, with endoscopic control permitting visualization of its cut edges. Study design. A ten-center study compared conventional open primary carpal tunnel release with closed endoscope-assisted release. The study design was reviewed and approved by each center's institutional review board, and informed consent was obtained from each patient. Patients were required to meet entry criteria designed to identify idiopathic carpal tunnel syndrome supported by abnormal nerve studies but normal electromyograms. Patient inclusion/ exclusion criteria included the absence of generalized peripheral neuropathy as well as diabetes mellitus or thyroid disease, anatomic abnormalities of the wrist and hand (including previous displaced fractures), inflammatory joint diseases, a history of median nerve injury from trauma (including contusion, fracture of the distal radius or wrist joint, etc.), previous surgery on the wrist, vasospastic disorders such as Raynaud's disease or sympathetic dystrophies and their equivalents, psychiatric disorders, chronic renal disease requiring dialysis, previous carpal tunnel release, thenar weakness sufficient to require tendon transfer to support thumb opposition at the time of carpal tunnel release (Camitz or other), and any other surgery required at the time of carpal tunnel release. There were 122 patients in the study; 25 had carpal tunnel surgery on both hands and 97 had surgery on one hand. Thus a total of 147 carpal tunnel procedures were performed. Of these, 82 were in the device group and 65 were in the conventional open surgical control group. Of the patients with unilateral procedures, 79 were workers; of these, 49 were in the device group and 30 were in the control group. The only significant difference between the two treatment groups was the use of diuretics during preoperative treatment of the carpal tunnel syndrome in 2 of 82 patients in the device group and 7 of 65 patients in the control group. Some differences were expected on the basis of chance alone; however, these differences should not have had a material effect on the results.
Vol. 17A, No.6 November 1992
Endoscopic relase of carpal funnel
989
Blade Assembly
Fig. 2. Safe zone of blade elevation. The safe zone is within a triangle defined by the ulnar half of the distal edge of the transverse carpal ligament (a), the ulnar border of the median nerve, i.e., its common digital branch (b), and the ulnar proximal margin of the superficial palmar arch (c) .
....
Fig. 3. Transverse carpal ligament incision on withdrawal of device.
In patients who had bilateral carpal tunnel syndrome, each hand was operated on in a separate procedure. In the early part of the study, the first hand to be treated surgically was randomized into the control or device groups. Frequently, those patients who had the first carpal tunnel release performed endoscopically refused to have the other hand treated with the conventional open surgical approach. Later in the study, patients with bilateral carpal tunnel syndrome had the control surgery first, followed by surgery with the endoscopic device on the opposite hand. Clinical examination. Before surgery, the following tests were performed on the affected and unaffected hands: grip strength with Jamar dynamometer readings at five settings; pinch strength, both lateral/key and
pulp; Semmes-Weinstein monofilament sensory mapping; Phalen's wrist flexion test; Tinel's test at the carpal tunnel; and manual motor testing, with grades 0 through 5, for thumb abduction. In addition, all patients had preoperative wrist x-ray films, including a carpal tunnel view (normal films were required for patient participation). All patients were questioned about any drug therapy they had received in the 4 weeks preceding entry into the study. At postoperative weeks 1, 2, 3, 6, 9, 13, and 26, the following data were collected: employment status, return of hand use for ADL, postoperative symptoms (same as preoperative), and clinical examination data for comparison with the preoperative data (grip and pinch measurements, monofilament sensory examina-
990
Agee et al.
tion, motor testing of thenar muscles, etc.) Grip strength was never tested at week 1 because of wound healing. In addition, scar tenderness and radial and ulnar pillar tenderness were graded from 0 to 4 (none to very tender), and a record of medication use was completed. Data analysis. For evaluation of the effect of surgery within each treatment group at each visit, the hypothesis of no change from preoperative evaluation was tested. For quantitative variables, such as percentage change from preoperative values, paired t tests" were used. For categorical variables, such as normal! abnormal, McNemar's test" was used. Retired persons, housewives, and persons who had bilateral surgical procedures were excluded from analysis of times for return to work. In the comparison of times of return to ADL, patients who had bilateral surgery were included with those who had unilateral surgery. The data for return to ADL by the two treatment groups of bilateral surgery patients also were compared separately by the Wilcoxon two-sample rank test. 6 The Kaplan-Meier method? was used to estimate median times of return to work and to ADL. Treatment groups were compared on the basis of times of return to work and to ADL by means of a survival analysis version of the Wilcoxon test. 8 Results Strength, sensory, and motor testing. Hands in both treatment groups were weaker in the early postoperative period than they were before surgery. Hands in both' groups became stronger with time. Patients in the device group returned to preoperative or greater strength more quickly than those in the control group (p < 0.05, Table I). There was no difference in sensory and motor (thenar) test results between the device and control groups (Table II). Within both treatment groups, sensory test results improved (p < 0.05) at week 2 as compared with preoperative measurements, except those for the small finger, which showed little if any subsequent improvement. Motor tests showed continual improvement in both groups, with both groups eventually exceeding preoperative levels. Phalen's and Tinel's test scores improved dramatically and similarly in the two groups (p < 0.05, Table III). Patient assessments. As shown in Table IV, the percentage of patients with pain, tingling, weakness, and numbness decreased over the course of the study within both treatment groups (p < 0.05). However, one of four patients in each group was still reporting some pain 6 months after surgery. Similarly, 6 months after surgery, about one patient in eight reported tingling,
The Journal of HAND SURGERY
one in three was reporting weakness, and one in six was reporting numbness. Table V shows that patients in the device group experienced less scar tenderness throughout the study than did controls, with the difference being statistically significant at weeks 1,2,3, and 9. The device group also experienced less radial pillar tenderness 3 and 9 weeks after surgery, and less ulnar pillar tenderness 1 week after surgery, while tenderness reported during the remaining visits was comparable in the two groups. Median times of return to work and to ADL. The 50% line in Fig. 4 shows that the median time for patients with unilateral surgery to return to work was 25 days for the device group and 46.5 days for the control group (p < 0.01). Patients with workers' compensation took much longer to return to work than did patients without workers' compensation. The median time to return to work for patients on workers' compensation was 71 days in the device group and 78 days in the control group (Table VI). Among patients not receiving workers' compensation, the device group had a greater advantage in time for return to work over the control group (p < 0.01) than was observed when all patients in the two groups were compared. Median time to return to work for unilateral surgery patients without workers' compensation in the device group was 16.5 days as compared to 45.5 days in the control group (Fig. 5 and Table VI). Also, 75% of the patients in the device group had returned to work by 42 days whereas it took 52 days for 75% of the control patients to return to work. (Fig. 5). The median times for return to ADL for all patients, with and without workers' compensation, are shown in Table VI. For the patients without workers' compensation, these times were 5 and 13 days, respectively, for the device and control groups (p < 0.01). Of the 25 patients with bilateral operations, 16 returned to ADL sooner with the device-treated hand than they did with the control hand. The difference was not statistically significant. Center effect. In a multicenter study, there is a possibility that a few centers could influence the results in a given direction whereas other centers could have the opposite effect. When data from each center were examined separately, there was reasonable uniformity in the results across centers, with the direction of the effect being the same for virtually all centers. Complications. TWo patients in the device group had persistent signs and symptoms of carpal tunnel syndrome that required reoperation by conventional open surgery. One patient, with an incomplete release of the proximal extent of the transverse carpal ligament, had complete resolution of symptoms after surgery. The
Vol. 17A, No.6 November 1992
Endoscopic relase of carpal IUIl/Iel
991
Table I. Strength by time since surgery Mean percent changefrom preoperative value Postoperative week Strength measurement" group Jamar grip Device Control Lateral I key pinch Device Control Pulp pinch Device Control Sample sizet Device Control
I NA NA
2
I
6
I
3
I
I
9
/3
I
26 14~
-55
-2U -38
-12 -22
-16§ -32
-211 -19
6
m
14~
21~
-52
-I
3
10
14~
-26 -52
-28
-II
I
10 7t
9 17
1411 17
74 51
74 60
79 57
73 57
72
59
64 48
-33~
-27~
-4
-II§
-4 -14
6t
72
-2
9
55
'Strength was measured in pounds and expressed as percent change from preoperative value. tSample sizes are maxima; for some variables, a small number of observations was missing. *Significant improvement compared with control, p -c 0.001. §Significant improvement compared with control, p
