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The effect of cold therapy on pain, swelling, and range of motion after anterior cruciate ligament reconstructive surgery
Arthroscopy: The Journal of Arthroscopic and Related Surgery 10(5):530-533 Published by Raven Press, Ltd. © 1994 Arthroscopy Associationof North America
The Effect of Cold Therapy on Pain, Swelling, and Range of Motion After Anterior Cruciate Ligament Reconstructive Surgery Dale M. Daniel, M.D., Mary Lou Stone, R.P.T., and Diana L. Arendt, R.N., M.S.N.
Summary: This prospective study assessed the effect of cold therapy on pain, pain medication use, limb swelling, and knee range of motion in 131 patients who had an arthroscopically assisted anterior cruciate ligament reconstruction. Patients were randomized into five treatment groups. Cooling pads were incorporated into the dressing in 89 patients, and no cooling pads were used in 42 patients. There were four cooling-pad temperature groups: 40°F, 45°F, 55°F, and 70°F. The cooling pads lowered the skin temperature. There was no difference between groups with respect to hospital stay, pain medication use, pain scale, knee girth, or range of motion. Key Words: ACL---Ligament reconstruction--Cold therapy--Knee surgery--Pain--Knee motion.
gitudinal incision was used to harvest the graft and make the tibial tunnel. A 5- to 8-cm lateral incision was used to place the femoral tunnel. No extraarticular surgery was performed. Forty-five patients had meniscus repairs during the index surgery, 37 medial, six lateral, and two combined medial and lateral. No tourniquet was used in 72% of the cases. The mean operative time was 186 min. Between February 1990 and April 1991, two 12 × 25 cm cooling pads were placed on each side of the knee at the conclusion of surgery. The pads were connected by hoses to a cooling unit (DuoTemp, Seabrook Medical, Cincinnati, OH, U.S.A.). A temperature sensor was placed on the patient's skin on the lateral side of the knee at the level of the joint line. The wound was then covered with one layer of gauze. The cooling pads were then applied. A second sensor was applied to the knee surface of the cooling pad. Additional dressings were then applied, and the limb was immobilized in 0 ° of flexion in a long-leg brace. The cooling-machine temperature, the cooling-pad temperature, and the skin temperature were recorded each day at 4 a.m. While the patient was in the hospital, the brace was removed for 3 h twice a day for the patient to be placed on a passive-motion machine. The cooling
The use of cold application to reduce pain and swelling after musculoskeletal trauma is common practice (1-3). Recently, continuous cold therapy has been used after knee ligament surgery to reduce postoperative pain and swelling (4,5). Our study was designed to evaluate the effect of temperature cooling pads used after anterior cruciate ligament (ACL) reconstruction to reduce the patients' pain, limb swelling, and joint stiffness. MATERIALS AND METHODS Between February 1990 and November 1991, postoperative pain, swelling, and joint stiffness were documented after arthroscopy-assisted patellar tendon graft ACL reconstructive surgery in 131 patients. The mean patient age was 27. In 11% of patients, surgery was performed within 6 weeks of their ACL disruption, and in 89%, >6 weeks after the injury date. A 10- to 15-cm anterior medial IonFrom the Department of Orthopedic Surgery, Kaiser Permanente Medical Group and the Kaiser Hospital, San Diego, California, U.S.A. Address correspondence and reprint requests to Dr. D. M. Daniel, Department of Orthopedic Surgery, Kaiser Hospital, 4647 Zion Avenue, San Diego, CA 92120, U.S.A.
530
THE E F F E C T OF COLD T H E R A P Y A F T E R A C L S U R G E R Y
531
T A B L E 1. Patient population
All Pad temperature
40°F
45°F
55°F
700F
No pad
Number Mean age Male (%) Surgery within 42 days of ACL injury (%) Meniscus repair (%) Cases using a tourniquet (%) Mean surgery time (min) Mean hospital days
16 27 69
30 27 63
13 27 62
30 27 83
42 26 71
13 13 37 199 3.1
13 47 27 191 3.1
15 38 62 201 3.3
10 40 23 178 3.2
10 29 14 174 3.2
patients 131 27 71 11 34 28 186 3.1
ACL, anterior cruciate ligament.
pads were continued during passive-motion treatments. The passive-motion machine was set to cycle at 1 r/min from 0 to 45 °. The arc of motion was progressed as tolerated by the patient. A continuous-passive-motion machine was not used after the patient left the hospital. After discharge, the patient was instructed to remove the knee brace four times a day and perform well-leg-assisted range-ofmotion exercises for 10 to 15 min. Patients were seen once a week by a physical therapist (M.L.S.) to monitor progress and direct the exercise program. The patient population was divided into five treatment groups with respect to the use of cooling pads, as shown in Table 1. Between February 1990 and September 1990, with informed patient consent, 50 patients were randomized into four coolingpad temperature groups as follows (Fahrenheit temperature/patient number): 40° (16), 45 ° (11), 55° (13), and 70° (10). To increase the possibility of detecting a difference between treatment groups, from October 1990 to April 1991, patients were randomized into two cooling-pad temperature groups: 45 ° (19) and 70° (20). Cooling pads were attached to the cooling machine set at the assigned temperature in the recovery room. The pads were connected to the cooling machine whenever the patient was in bed. The patients were out of bed daily to walk with crutches and perform active exercises in physical therapy. A timing device on one of the machines recorded the time the machine was in use. The cooling machine was discontinued on the third postoperative day or the day of patient discharge, whichever came first. Between May 1991 and November 1991, cooling pads were not applied (n = 42). A temperature sensor was placed on the lateral aspect of the knee. Knee girth and range-of-motion measurements were made preoperatively, on postop day three, or
at the time of patient discharge from the hospital, whichever came first, and 10 to 14 days after surgery. Knee girth measurements were made of both knees with a tape measure at the level of the midpatella. Knee extension was recorded as flexion contracture compared to the contralateral knee using the technique of centimeters of prone heelheight difference (6). Flexion was recorded as prone active-assisted knee flexion. All medications during the hospitalization were ordered on an as-needed basis. Medications used during the hospitalization were extracted from the patient's hospital record and converted to units of pain medication with the use of a pain medication equivalency table (7). One unit of parenteral pain medicine equals 75 mg meperidine (Demerol), and one unit of oral pain medication equals 60 mg codeine. On the third postoperative day or at the time of discharge, whichever came first, the patient was asked to mark on a 10cm analog scale to rate the overall level of postoperative pain during the hospitalization, from no pain to the most pain imaginable. Limb girth and rangeof-motion measurements before and 10 to 14 days after surgery were performed by author M.L.S. Measurements during hospitalization were recorded by the patient's nurse. Study data were entered into a desk-top computer for processing and statistical analysis. Oneway analysis of variance (ANOVA) was used to compare groups for continuous variables (knee T A B L E 2. Machine, pad and skin temperature Machine
Pad
Skin
40 45 55 70 No pad
51 57 64 75
82 81 83 90 98
Results in degrees Fahrenheit.
Arthroscopy, Vol. 10, No. 5, 1994
532
D. M. D A N I E L E T AL. T A B L E 3. Patient pain grading and use o f
pain medication
Pad temperature 40 45 55 70 Nop~ ~lp~ients
Parenteral pain medication
Oral pain medication
Patient grading of postoperative pain
Units
SD
Units
SD
Units
SD
5.5 5.3 4.8 4.4 4.8 4.9
4.1 4.3 3.8 2.6 2.9 3.4
8.8 8.6 9.4 9.9 10.2 9.5
3.0 3.6 3.4 4.0 4.5 3.9
4.1 4.6 5.7 4.9 4.6 4.7
2.1 1.7 2.0 2.4 2.0 2.1
girth, knee flexion, heel-height difference, and pain score).
evaluation of pain during the hospitalization are presented in Table 3. There was no difference in parenteral or oral pain medication between groups; power to detect a three-unit difference, >80%. There was no difference in the evaluation of pain between groups; power to detect a 2.5-unit difference, >80%. The knee girth difference 3 days after surgery was 4.7 cm and 10 to 14 days after surgery was 2.8 cm. There was no difference between treatment groups. Ten to 14 days after surgery, the average flexion contracture was 4.1 ° and flexion, 74.1 °. There was no difference between treatment groups (Table 4). All wounds healed primarily without infection. DISCUSSION
RESULTS All patients in the cold-pad group tolerate the cold pads, though two patients asked that the pad be moved to the next higher temperature (40 to 45°F and 55 to 70°F). Many patients reported to the nurse that the pads felt good, especially when the pads were first connected to the cooling machine after a period of exercise. Total hours of cooling machine use averaged 57 h in the 38 patients using the machine with a timer. Cooling pads were wanner than the temperature of the machine in all groups. The cooling pads decreased the skin temperature in all groups (Table 2). Days of hospitalization varied from 2 to 5 days and averaged 3.2. There was no difference between patient groups. Use of pain medication and patient
There are data to support the thesis that cold therapy after limb trauma decreases limb swelling (3,8). Pain relief with cold therapy is believed to result from a decrease in soft tissue swelling, a decrease in muscle spasm, and an effect on the pain threshold (3,9). Topically applied cold therapy has been demonstrated to reduce deep muscle temperature (10). Nerve palsy has been reported after cryotherapy (11). The only previous study of cold therapy after knee surgery was reported by Cohn et al. (4). The authors randomized 54 patients undergoing arthroscopy-assisted ACL surgery into two treatment groups. Group I used a cold blanket on the knee with the cooling device set at 50°F, and Group II was treated without a cold blanket. They did not measure limb girth or range of motion. They
T A B L E 4. Knee range o f motion and girth Measurement Knee girth (cm) Injured - normal
Heel height difference Injured - normal (cm)
Flexion (degrees)
Arthroscopy, Vol. 10, No. 5, 1994
Pad temp 40 45 55 70 Nop~ 40 45 55 70 No pad 40 45 55 70 No pad
Preop 0.2 0.5 0.2 0.5 0.5 2.1 2.1 3.9 2.0 1.6 131 127 128 129 132
Postop day 3
At suture removal
4.7 4.8 4.8 4.7 4.6
2.9 3.0 2.9 2.6 2.5 3.5 4.8 4.3 4.7 3.5 72 72 72 72 78
THE EFFECT OF COLD THERAPY AFTER ACL SURGERY
d o c u m e n t e d that the a v e r a g e hospital stay of 3.5 days was not altered b y cold therapy. T h e y did docu m e n t a d e c r e a s e in parenteral pain medication in the cold t h e r a p y group. In this study, we d e m o n s t r a t e d that cold therapy d e c r e a s e d k n e e skin t e m p e r a t u r e ; h o w e v e r , w e d e m o n s t r a t e d no benefit o f cold therapy. T h e r e was no r e d u c t i o n in p a i n - m e d i c a t i o n use or hospital stay. T h e r e was no reduction in limb swelling or increase in range o f motion. Acknowledgment: This project was funded in part by Seabrook Medical, Cincinnati, Ohio. The authors thank the nursing staff at E1 Cajon Hospital for data collecting, Jennifer Sachs and Nancy Johnson for assistance in data processing, and Kenton Kaufman, Ph.D., for assistance m statistical analysis. REFERENCES 1. Budassi-Sheehy S, Barber J. Emergency nursing: principles and practice. St. Louis, Missouri: CV Mosby Company, 1985.
533
2. Grana W, Karr J, Stafford M. Rehabilitation techniques for athletic injury. In: Stauffer ES, ed. Instructional Course Lectures. St. Louis, Missouri: CV Mosby Company, 1985;00-00. 3. Lehmann JF, Warren CG, Scham SM. Therapeutic heat and cold. Clin Orthop 1974;90:207--45. 4. Cohn BT, Draeger RI, Jackson DW. The effects of cold therapy in the postoperative management of pain in patients undergoing anterior cruciate ligament reconstruction. Am J Sports Med 1989;17:344-9. 5. Shelbourue KD, Wilckens JH. Current concepts in anterior cruciate ligament rehabilitation. Orthop Rev 1990;19:957--64. 6. Sachs RA, Daniel DM, Stone ML, et al. Patellofemoral problems after anterior cruciate ligament reconstruction. Am J Sports Med 1989;17:760-5. 7. Gilman AG, Rail TW, Nies AS, Taylor P. The pharmacological basis of therapeutics. New York: Pergamon Press, 1990. 8. McMaster WC, Liddle S. Cryotherapy influence on posttraumatic limb edema. Clin Orthop 1980;150:283-7. 9. Kowal M. Review of physiological effects of cryotherapy. J Orthop Sports Phys Ther 1983;Sept/Oct:66-73. 10. McMaster WC, Liddle S, Waugh TR. Laboratory evaluation of various cold therapy modalities. Am J Sports Med 1978; 6:291--4. ! 1. Drez D, Faust DC, Evans JP. Cryotherapy and nerve palsy. Am J Sports Med 1981;9:256--7.
Arthroscopy, Vol. 10, No. 5, 1994
The Effect of Cold Therapy on Pain, Swelling, and Range of Motion After Anterior Cruciate Ligament Reconstructive Surgery Dale M. Daniel, M.D., Mary Lou Stone, R.P.T., and Diana L. Arendt, R.N., M.S.N.
Summary: This prospective study assessed the effect of cold therapy on pain, pain medication use, limb swelling, and knee range of motion in 131 patients who had an arthroscopically assisted anterior cruciate ligament reconstruction. Patients were randomized into five treatment groups. Cooling pads were incorporated into the dressing in 89 patients, and no cooling pads were used in 42 patients. There were four cooling-pad temperature groups: 40°F, 45°F, 55°F, and 70°F. The cooling pads lowered the skin temperature. There was no difference between groups with respect to hospital stay, pain medication use, pain scale, knee girth, or range of motion. Key Words: ACL---Ligament reconstruction--Cold therapy--Knee surgery--Pain--Knee motion.
gitudinal incision was used to harvest the graft and make the tibial tunnel. A 5- to 8-cm lateral incision was used to place the femoral tunnel. No extraarticular surgery was performed. Forty-five patients had meniscus repairs during the index surgery, 37 medial, six lateral, and two combined medial and lateral. No tourniquet was used in 72% of the cases. The mean operative time was 186 min. Between February 1990 and April 1991, two 12 × 25 cm cooling pads were placed on each side of the knee at the conclusion of surgery. The pads were connected by hoses to a cooling unit (DuoTemp, Seabrook Medical, Cincinnati, OH, U.S.A.). A temperature sensor was placed on the patient's skin on the lateral side of the knee at the level of the joint line. The wound was then covered with one layer of gauze. The cooling pads were then applied. A second sensor was applied to the knee surface of the cooling pad. Additional dressings were then applied, and the limb was immobilized in 0 ° of flexion in a long-leg brace. The cooling-machine temperature, the cooling-pad temperature, and the skin temperature were recorded each day at 4 a.m. While the patient was in the hospital, the brace was removed for 3 h twice a day for the patient to be placed on a passive-motion machine. The cooling
The use of cold application to reduce pain and swelling after musculoskeletal trauma is common practice (1-3). Recently, continuous cold therapy has been used after knee ligament surgery to reduce postoperative pain and swelling (4,5). Our study was designed to evaluate the effect of temperature cooling pads used after anterior cruciate ligament (ACL) reconstruction to reduce the patients' pain, limb swelling, and joint stiffness. MATERIALS AND METHODS Between February 1990 and November 1991, postoperative pain, swelling, and joint stiffness were documented after arthroscopy-assisted patellar tendon graft ACL reconstructive surgery in 131 patients. The mean patient age was 27. In 11% of patients, surgery was performed within 6 weeks of their ACL disruption, and in 89%, >6 weeks after the injury date. A 10- to 15-cm anterior medial IonFrom the Department of Orthopedic Surgery, Kaiser Permanente Medical Group and the Kaiser Hospital, San Diego, California, U.S.A. Address correspondence and reprint requests to Dr. D. M. Daniel, Department of Orthopedic Surgery, Kaiser Hospital, 4647 Zion Avenue, San Diego, CA 92120, U.S.A.
530
THE E F F E C T OF COLD T H E R A P Y A F T E R A C L S U R G E R Y
531
T A B L E 1. Patient population
All Pad temperature
40°F
45°F
55°F
700F
No pad
Number Mean age Male (%) Surgery within 42 days of ACL injury (%) Meniscus repair (%) Cases using a tourniquet (%) Mean surgery time (min) Mean hospital days
16 27 69
30 27 63
13 27 62
30 27 83
42 26 71
13 13 37 199 3.1
13 47 27 191 3.1
15 38 62 201 3.3
10 40 23 178 3.2
10 29 14 174 3.2
patients 131 27 71 11 34 28 186 3.1
ACL, anterior cruciate ligament.
pads were continued during passive-motion treatments. The passive-motion machine was set to cycle at 1 r/min from 0 to 45 °. The arc of motion was progressed as tolerated by the patient. A continuous-passive-motion machine was not used after the patient left the hospital. After discharge, the patient was instructed to remove the knee brace four times a day and perform well-leg-assisted range-ofmotion exercises for 10 to 15 min. Patients were seen once a week by a physical therapist (M.L.S.) to monitor progress and direct the exercise program. The patient population was divided into five treatment groups with respect to the use of cooling pads, as shown in Table 1. Between February 1990 and September 1990, with informed patient consent, 50 patients were randomized into four coolingpad temperature groups as follows (Fahrenheit temperature/patient number): 40° (16), 45 ° (11), 55° (13), and 70° (10). To increase the possibility of detecting a difference between treatment groups, from October 1990 to April 1991, patients were randomized into two cooling-pad temperature groups: 45 ° (19) and 70° (20). Cooling pads were attached to the cooling machine set at the assigned temperature in the recovery room. The pads were connected to the cooling machine whenever the patient was in bed. The patients were out of bed daily to walk with crutches and perform active exercises in physical therapy. A timing device on one of the machines recorded the time the machine was in use. The cooling machine was discontinued on the third postoperative day or the day of patient discharge, whichever came first. Between May 1991 and November 1991, cooling pads were not applied (n = 42). A temperature sensor was placed on the lateral aspect of the knee. Knee girth and range-of-motion measurements were made preoperatively, on postop day three, or
at the time of patient discharge from the hospital, whichever came first, and 10 to 14 days after surgery. Knee girth measurements were made of both knees with a tape measure at the level of the midpatella. Knee extension was recorded as flexion contracture compared to the contralateral knee using the technique of centimeters of prone heelheight difference (6). Flexion was recorded as prone active-assisted knee flexion. All medications during the hospitalization were ordered on an as-needed basis. Medications used during the hospitalization were extracted from the patient's hospital record and converted to units of pain medication with the use of a pain medication equivalency table (7). One unit of parenteral pain medicine equals 75 mg meperidine (Demerol), and one unit of oral pain medication equals 60 mg codeine. On the third postoperative day or at the time of discharge, whichever came first, the patient was asked to mark on a 10cm analog scale to rate the overall level of postoperative pain during the hospitalization, from no pain to the most pain imaginable. Limb girth and rangeof-motion measurements before and 10 to 14 days after surgery were performed by author M.L.S. Measurements during hospitalization were recorded by the patient's nurse. Study data were entered into a desk-top computer for processing and statistical analysis. Oneway analysis of variance (ANOVA) was used to compare groups for continuous variables (knee T A B L E 2. Machine, pad and skin temperature Machine
Pad
Skin
40 45 55 70 No pad
51 57 64 75
82 81 83 90 98
Results in degrees Fahrenheit.
Arthroscopy, Vol. 10, No. 5, 1994
532
D. M. D A N I E L E T AL. T A B L E 3. Patient pain grading and use o f
pain medication
Pad temperature 40 45 55 70 Nop~ ~lp~ients
Parenteral pain medication
Oral pain medication
Patient grading of postoperative pain
Units
SD
Units
SD
Units
SD
5.5 5.3 4.8 4.4 4.8 4.9
4.1 4.3 3.8 2.6 2.9 3.4
8.8 8.6 9.4 9.9 10.2 9.5
3.0 3.6 3.4 4.0 4.5 3.9
4.1 4.6 5.7 4.9 4.6 4.7
2.1 1.7 2.0 2.4 2.0 2.1
girth, knee flexion, heel-height difference, and pain score).
evaluation of pain during the hospitalization are presented in Table 3. There was no difference in parenteral or oral pain medication between groups; power to detect a three-unit difference, >80%. There was no difference in the evaluation of pain between groups; power to detect a 2.5-unit difference, >80%. The knee girth difference 3 days after surgery was 4.7 cm and 10 to 14 days after surgery was 2.8 cm. There was no difference between treatment groups. Ten to 14 days after surgery, the average flexion contracture was 4.1 ° and flexion, 74.1 °. There was no difference between treatment groups (Table 4). All wounds healed primarily without infection. DISCUSSION
RESULTS All patients in the cold-pad group tolerate the cold pads, though two patients asked that the pad be moved to the next higher temperature (40 to 45°F and 55 to 70°F). Many patients reported to the nurse that the pads felt good, especially when the pads were first connected to the cooling machine after a period of exercise. Total hours of cooling machine use averaged 57 h in the 38 patients using the machine with a timer. Cooling pads were wanner than the temperature of the machine in all groups. The cooling pads decreased the skin temperature in all groups (Table 2). Days of hospitalization varied from 2 to 5 days and averaged 3.2. There was no difference between patient groups. Use of pain medication and patient
There are data to support the thesis that cold therapy after limb trauma decreases limb swelling (3,8). Pain relief with cold therapy is believed to result from a decrease in soft tissue swelling, a decrease in muscle spasm, and an effect on the pain threshold (3,9). Topically applied cold therapy has been demonstrated to reduce deep muscle temperature (10). Nerve palsy has been reported after cryotherapy (11). The only previous study of cold therapy after knee surgery was reported by Cohn et al. (4). The authors randomized 54 patients undergoing arthroscopy-assisted ACL surgery into two treatment groups. Group I used a cold blanket on the knee with the cooling device set at 50°F, and Group II was treated without a cold blanket. They did not measure limb girth or range of motion. They
T A B L E 4. Knee range o f motion and girth Measurement Knee girth (cm) Injured - normal
Heel height difference Injured - normal (cm)
Flexion (degrees)
Arthroscopy, Vol. 10, No. 5, 1994
Pad temp 40 45 55 70 Nop~ 40 45 55 70 No pad 40 45 55 70 No pad
Preop 0.2 0.5 0.2 0.5 0.5 2.1 2.1 3.9 2.0 1.6 131 127 128 129 132
Postop day 3
At suture removal
4.7 4.8 4.8 4.7 4.6
2.9 3.0 2.9 2.6 2.5 3.5 4.8 4.3 4.7 3.5 72 72 72 72 78
THE EFFECT OF COLD THERAPY AFTER ACL SURGERY
d o c u m e n t e d that the a v e r a g e hospital stay of 3.5 days was not altered b y cold therapy. T h e y did docu m e n t a d e c r e a s e in parenteral pain medication in the cold t h e r a p y group. In this study, we d e m o n s t r a t e d that cold therapy d e c r e a s e d k n e e skin t e m p e r a t u r e ; h o w e v e r , w e d e m o n s t r a t e d no benefit o f cold therapy. T h e r e was no r e d u c t i o n in p a i n - m e d i c a t i o n use or hospital stay. T h e r e was no reduction in limb swelling or increase in range o f motion. Acknowledgment: This project was funded in part by Seabrook Medical, Cincinnati, Ohio. The authors thank the nursing staff at E1 Cajon Hospital for data collecting, Jennifer Sachs and Nancy Johnson for assistance in data processing, and Kenton Kaufman, Ph.D., for assistance m statistical analysis. REFERENCES 1. Budassi-Sheehy S, Barber J. Emergency nursing: principles and practice. St. Louis, Missouri: CV Mosby Company, 1985.
533
2. Grana W, Karr J, Stafford M. Rehabilitation techniques for athletic injury. In: Stauffer ES, ed. Instructional Course Lectures. St. Louis, Missouri: CV Mosby Company, 1985;00-00. 3. Lehmann JF, Warren CG, Scham SM. Therapeutic heat and cold. Clin Orthop 1974;90:207--45. 4. Cohn BT, Draeger RI, Jackson DW. The effects of cold therapy in the postoperative management of pain in patients undergoing anterior cruciate ligament reconstruction. Am J Sports Med 1989;17:344-9. 5. Shelbourue KD, Wilckens JH. Current concepts in anterior cruciate ligament rehabilitation. Orthop Rev 1990;19:957--64. 6. Sachs RA, Daniel DM, Stone ML, et al. Patellofemoral problems after anterior cruciate ligament reconstruction. Am J Sports Med 1989;17:760-5. 7. Gilman AG, Rail TW, Nies AS, Taylor P. The pharmacological basis of therapeutics. New York: Pergamon Press, 1990. 8. McMaster WC, Liddle S. Cryotherapy influence on posttraumatic limb edema. Clin Orthop 1980;150:283-7. 9. Kowal M. Review of physiological effects of cryotherapy. J Orthop Sports Phys Ther 1983;Sept/Oct:66-73. 10. McMaster WC, Liddle S, Waugh TR. Laboratory evaluation of various cold therapy modalities. Am J Sports Med 1978; 6:291--4. ! 1. Drez D, Faust DC, Evans JP. Cryotherapy and nerve palsy. Am J Sports Med 1981;9:256--7.
Arthroscopy, Vol. 10, No. 5, 1994