Cryotherapy for postoperative pain relief following knee arthroplasty
The Journal of Arthroplasty Vol. 9 No. 3 1994 Cryotherapy for Postoperative Pain Relief Following Knee Arthroplasty Marty Ivey, MD, Robert V. Johnston, MD, and Tatsuo Uchida, MS Abstract: Ninety consecutive patients undergoing primary knee arthroplasty received local cryotherapy 72 hours after surgery for pain relief. Thermal-pad circulating tem- peratures were randomly assigned to 50”. 60”, or 70°F (room temperature). Pain relief was monitored using patient-controlled analgesia machines. The amount of morphine received and number of attempts per hour were statistically analyzed with relation to temperature group, age, sex, weight, side, and diagnosis. The amount of morphine injected was positively correlated to the number of attempts per hour and moderately correlated to body weight. There was no correlation between thermal-pad temperature or any other parameter and the amount of morphine injected after surgery. Key words: cryotherapy, postoperative, pain, knee, arthroplasty. The application of cold has been used extensively rior-stabilized prosthesis (Zimmer IB-II, Warsaw, IN)to decrease pain, edema, muscle spasm, hemorrhage, was implanted in each patient by the same surgeon.and the inflammatory response after injury. * Recent The skin incision was closed with metal staples andreports have cited the benefits of cryotherapy in the a single layer of gauze/cast padding dressing was ap-treatment of patients undergoing knee surgery for plied. Hot Ice thermal pads (Pro-Action Medical, Oakpatellar problems or anterior cruciate ligament re- Ridge, TX) were applied to either side of the incisionconstruction.‘,3 To determine the efficacy of cryo- and held in place with three additional layers of casttherapy in reducing postoperative pain following padding and an elastic bandage. A knee immo-knee arthroplasty, 90 consecutive patients were ran- bilizer was applied and the thermal pads weredomly assigned to three thermal-pad temperatures attached distally to the Hot Ice machine (Pro-Actionof 50”. 60”, and 70’F (room temperature). Postopera- Medical).tive pain responses were determined by the amount Prior to the study, 30 sets of three random numbersof morphine the patients received and the number were drawn from the uniform distribution on theof attempts per hour as monitored by a patient-con- interval 0, 1 using the function UNIFORM in the SAStrolled analgesia (PCA) machine. System (Cary, NC). The three random numbers in each set were then transformed into ranks. This re- sulted in 30 sets of random sequences, each with Materials and Methods the integers I, 2, and 3. Patients entering the study received one of three treatments according to the fol- This study was approved by our Institutional Re- lowing assignment: 1, 50”; 2, 60”; and 3, 70°F. Forview Board. Ninety consecutive patients undergoing example, consider 2, 3, 1 and 3, 2, 1 as the first twoprimary knee arthroplasty comprised the study sets. Using this example, the first six consecutive pa-group. Thirty patients were assigned to each temper- tients would have been assigned to the temperatureature group. A cemented, cruciate-sacrificing, poste- group in the order of 60”, 70”, 50”, 70”, 60”, and 50°F. Patients were randomly assigned, as described, to From i/w Univrrcit~v oj Trxds Moiical Branch. GdVeStOFl, Texas. Reprint requests: Marty Ivcy, MD, University of Texas Medical one of three temperature groups-50”, 60”, or 70°FBranch. 6136 McCullough Buikting, Galveston, TX 77555-0792. (room temperature)-and the machine was pro- 285
286 The Journal of Arthroplasty Vol. 9 No. 3 June 1994grammed. Patients were unaware of their assigned and the number of successful administrations weretemperature group. stored hourly, and the data were reviewed and Patients were seen by a physical therapist on the recorded daily. The patients remained on PCA for 72morning after surgery and instructed on bed transfers hours after surgery.and isometric exercises for all muscle groups of the The amount of morphine and the number of at-operated extremity. On the second day after surgery tempts monitored by the PCA system were averagedpatients ambulated weight bearing as tolerated in per hour for analysis. The linear correlation coeffi-parallel bars. Seventy-two hours after surgery the cients (r) were computed to measure the strengthpostoperative dressing and thermal pads were re- of association between four response measurements:moved and the patient started active assistive range the amount of morphine injected, the number of at-of motion. tempts, age, and body weight. Twelve combinations The operative and postoperative pain were man- of three explanatory factors-treatment group (50”,aged by the anesthesia service. The choice of anes- 60”, and 70”F), sex (male and female), and knee (leftthetic technique was at the discretion of the attending and right)-were assessed using a one-way analysisanesthesiologist. Most patients received a balanced, of variance procedure (ANOVA) for each of the fourgeneral endotracheal anesthetic. One patient in response measurements. Also, the two types of diag-group 1 received a subarachnoid anesthetic. Contin- noses (osteoarthritis and rheumatoid arthritis) wereuous epidural anesthesia was performed for one pa- tested for those response measurements using one-tient in each of the three groups. There were no anes- way analysis of variance. All tests were performed atthetic-related complications. The quantity and type the P = .05 level of significance.of narcotics administered during surgery wererecorded. The patients were taken to the postanes-thesia recovery area, where upon awakening and Resultspresenting with pain they received intravenous mor-phine sulfate in 2 mg boluses every 10 minutes until There were no anesthetic, surgical, or medicalthey expressed comfort. The use of a PCA device was complications. All incisions healed primarily withoutreviewed with the patient. The first PCA dose admin- dehiscence, necrosis, or prolonged drainage. One Hotistered was 1 mg morphine sulfate with a 1O-minute Ice machine malfunctioned in the recovery room andlockout. In five instances the initial PCA settings was replaced within 1 hour. Two patients in groupwere modified to account for patient weight or age 1 (50°F) were dropped from the study group because (3 patients in group 1, 1 each in groups 2 and 3). A their postoperative records monitored by the PCAphysician was available on a 24-hour basis to inter- pump were lost. The patient profiles regarding age,vene in instances of inadequate analgesia. Such oc- body weight, treatment group, sex, side, and diagno-currences were first treated with a bolus of 2-4 mg sis are listed in Tables l-3.morphine sulfate and, if necessary, the PCA dose was The amount of morphine injected was correlatedincreased to l$ or 2 mg. The number of PCA requests to the number of attempts (r = .65) and moderately Table 1. Patient Profile (n = 88)Treatment Sex Knee Diagnosis 03 F M L R Osteoarthritis Rheumatoid Arthritis Total 50 16 12 13 15 27 1 28 60 19 II 17 13 28 2 30 70 22 8 15 15 28 2 30 Total 57 31 45 43 83 5 88 Table 2. Descriptive Statistics of Each Treatment Group for AgeTreatment No. of Mean Minimum Maximum (“F) Patients Wars) (y Sk) (years) (years) 50 28 64.5 8.1 53 85 60 30 64.2 10.3 36 85 70 30 66.9 11.6 36 88
Cryotherapy l lvey et al. 287 Table 3. Descriptive Statistics of Each Treatment Group for WeightTreatment No. of Mean Minimum Maximum (“F) Patients (lb) (lb) (lb) 50 2s 192 36 120 270 60 31) 182 36 107 259 70 30 188 39 118 267 Table 4. Descriptive Statistics of Each Treatment Group for Number of PCA AttemptsTreatment No. of Mean SD Minimum Maximum (“F) Patients (hour) (hour) (hour) (hour) - 50 2x 3.6 2.4 0.3 8.4 60 3( 3.4 2.8 0.2 IO.4 70 3(1 3.9 3.0 0.2 Il.6 PCA, patient-controlled analgesia. Table 5. Descriptive Statistics of Each Treatment Group for Amount of Morphine InjectedTreatment No. of Mean SD Minimum Maximum C’F) Patients OWN Wg/h) Ox/h) (mg/h) 50 28 1.6 0.8 0.2 3.2 60 30 1.4 0.7 0.2 s.3 70 30 1.3 0.6 0.2 2.6correlated to body weight (r = .47). Other pairs ofthe response measurements did not have notablecorrelations. Twelve combinations of three explana-tory factors (treatment group, sex, and knee) werenot significantly different for any of the four responsemeasurements. Thus, there were no significant differ-ences among treatment groups between sexes or be-tween knees for the amount of morphine injected .and the number of attempts (Tables 4, 5; Figs. 1, 2). :The same results can also be stated for age and body l bweight. Patients with rheumatoid arthritis tended to : b bhave a lower number of attempts and consequently . ba lower amount of morphine injected than patients . .‘.with osteoarthritis (P -= .07 and .08, respectively). bb b aebb .This tendency seemed to be due to a significantly be 20 .‘.lower body weight of the rheumatoid group than the b on bosteoarthritis group (P = ,003). nob b bbbb b b&b b on : . 2” b Discussion nob b A b . l 00 . .‘. b Clinically, the local application of cold progresses . b . lthrough four phases.4,4 sensation of cold is felt for3 minutes followed by an intense burning or aching 0’ I I Ifeeling up to 7 minutes. From 5 to 12 minutes numb- 50 60 70ness is felt followed by a deep vasodilation. Temp (OF) The pain-relieving effect of cold has been used for Fig. 1. Average amount of morphine administered percenturies.5 Hippocrates used the application of ice hour versusthermal pad temperature.
288 The Journal of Arthroplasty Vol. 9 No. 3 June 1994 . . . f . . . . .Fig. 2. Average number of pa- :tient-controlled analgesia at-tempts per hour versus ther- :mal pad temperature. . . v. . .. . I i i .. i 0% . : 80 : : .:. : . . : v l o* .. 5@0 ’ i0 Tern; (OF)and snow to effect anesthesia prior to surgical proce- twitch.” Reports are conflicting regarding the effectdures.6 Marco Aurelio Severino, an Italian anatomist of cold on local muscle blood flo~.‘~-~’ Cryotherapyand surgeon, applied snow in small tubes to render can also assist with proprioceptive neuromuscular fa-the skin insensible before making an incision.’ Dom- cilitation techniques for stretching to improve flexi-inique-Jean Larrey, Napoleon’s military surgeon, bility.22 Hartviksen applied ice packs to decreasedocumented the numbing effects of cold in battlefield muscle tone in spastic muscles.23 The triceps suracconditions of - 19°C ambient temperature, allowing muscle was examined by placing an intramuscularhim to perform amputations on soldiers.8 In 1943, probe 2$ to 3f cm deep within the muscle. This probeMock’ used ice bags to anesthetize donor sites for was not affected by the application of an ice packskin grafts, and in 195 1, Gibson” used a motor- until 10 minutes had passed. Hartviksen noted thatdriven refrigeration device for the same purpose. spasticity was decreased before the muscle tempera- The application of cold reduces pain by decreasing ture dropped and therefore the effect was throughnerve impulse conduction and the size of the nerve the skin application.action potential.’ ’ Nerve conduction is blocked The application of cold to control traumatically in-when its local temperature falls below 10°C. ” Large, duced edema has been used empirically in the past.myelinated motor fibers appear to be affected Matsen et al. used a rabbit model in an attempt tofirst.“,14 Cold application helps depress the excitabil- objectively quantify postfracture swelling by theity of free nerve endings, thus increasing the pain water displacement method.‘” A circumferentialthreshold.15 water bath surrounding the extremity with tempera- Cold application reduces involuntary muscle tures ranging from 5” to 25°C was utilized for 96spasm due to a relative deactivation of the muscle hours. The amount of swelling observed at 96 hoursspindle. I6 The application of cold elongates latent increased as the water bath temperature decreased.time, contraction time, and relaxation time of muscle Swelling started after the water bath was removed
Cryotherapy l key et al. 289and was primarily localized to the subcutaneous tis- for an additional 20-24 hours. The treatment groupsue. This postcooling edema has been noted by other had 74% good to excellent results in 1 week withoutauthors.15 complications, and the control group, which only McMaster and Liddle recognized that the clinical had a compression dressing prior to tourniquet re-use of ice was not well standardized as methods of lease, had only 32% good to excellent results withuse varied widely. ” They used a rabbit forelimb one infection and one quadriceps muscle extrava-crush model and measured postinjury swelling by sation.the water displacement method to determine the op- Hot ICC thermal pads were applied in a randomtimum application of cold. They reported that the fashion to patients undergoing anterior cruciate liga-early application of cold after injury was beneficial ment reconstruction.3 The thermal pads were set atin decreasing edema, but that extreme cold or pro- 50°F. The study group received pain medications thatlonged use were to be avoided. did not require many injections and were converted Cooling the entire body has been used to treat car- to oral pain medications 1.2 days sooner than thecinoma, psychiatric disorders, head injury, during control group. There was no difference in the lengthcardiac surgery, and in thyroid crises.26 In addition, of hospital stay or progression in physical therapycircumferential local refrigeration has been used for between the control and study groups at 6 weeksdamaged extremities requiring amputation second- after surgery.ary to inadequate circulation and infection. The effect of postoperative cryotherapy on pain re- Cold application should be avoided in patients lief was the only aspect of cold application evaluatedwith cold hypersensitivity syndromes.‘7,‘8 Cold in this study. Objective documentation of the amountshould also be avoided in rheumatoid patients who of morphine administered and the number of PCAhave symptoms of pain and stiffness, patients who attempts per hour was readily obtained. Commer-have anesthetic skin, patients who are comatose, and cial marketing presentations for these products spe-patients with certain athletic injuries where the anes- cifically mention that they will reduce postoperativethetic effect of cold may block protective sensation pain.and increase collagen stiffness. ’ 5 Previous investigators have noted that the applica- Cryotherapy used locally has been reported to tion of ice packs to the knee joints of dogs markedlycause peripheral nerve injury.“,” Superficial nerves, decreased the intraarticular temperature. ” Since thesuch as the ulnar nerve at the elbow, the peroneal skin is benumbed at 50°F ( lO”C), this temperaturenerve at the fibular neck, and the lateral femoral cu- was used as the lowest temperature in the trialtaneous nerve at the iliac crest, have been affected. groups. The ambient room temperature is close to Recommendations for avoiding this complication in- 70°F so we arbitrarily chose this as our upper tempcr-clude the application of cold less than 20 minutes ature. Ninety patients divided into three groupsand avoidance of thcsc particular subcutaneous would develop statistically significant results; therc-nerve locations. One should also avoid compression fore, a third temperature of 60°F was arbitrarilyand temperatures less than 10°C and use ice massage added to the study. rather than continuous compression. One criticism of this study is that the actual circu- In 1945, Schaubel reported on the local use of ice lating temperature of the liquid in each thermal pad after orthopedic procedures in 345 patients.“’ He was not tested and retested to document the accuracyfound that less casts wet-c cut and patients’ tempera- of the machines. All machines were inspected and ture, pulse, and respiratory rates were lower than serviced regularly by the parent company (Pro-Ac- those without ice application. He noted a more nor- tion Medical). mal white blood cell count, fewer postoperative com- All patients in the study group had Hot Ice thermal plications, and less need for narcotics. pads applied over one layer of postoperative dressing Hot Ice thermal pads have been used to accelerate adjacent to the midline skin incision. The thermal postoperative recovery and decrease the morbidity pads were held in place by additional absorbent associated with surgical procedures. Water conducts dressingsand a knee immobilizer. The knee immobi- heat away from an object more efficiently than air. 3 ’ lizer and underlying dressing were kept in place forThermal pads were applied in a random, double- a total of 72 hours, while the patient’s pain response blind, prospective study after electrosurgical lateral was monitored by a PCA machine using injectable release in 110 patients with patellar subluxation, pa- morphine. There were no wound complications or tellofemoral pain syndromes, chondromalacia of the nerve palsies from the use of the Hot Ice thermal patella, and patellar dislocation.” The treatment pads. In our study only the amount of morphine in- group had thermal pads at 50°F applied for 3 hours jected and the number of attempts were correlated and they used a postoperative refreezable ice wrap to the weight of the patients. The temperature of the
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