The use of dual-mobility bearings in patients at high risk of dislocation.

AIMS: Instability continues to be a troublesome complication after total hip arthroplasty (THA). Patient-related risk factors associated with a higher dislocation risk include the preoperative diagnosis, an age of 75 years or older, high body mass index (BMI), a history of alcohol abuse, and neurodegenerative diseases. The goal of this study was to assess the dislocation rate, radiographic outcomes, and complications of patients stratified as high-risk for dislocation who received a dual mobility (DM) bearing in a primary THA at a minimum follow-up of two years. MATERIALS AND METHODS: We performed a retrospective review of a consecutive series of DM THA performed between 2010 and 2014 at our institution (Hospital for Special Surgery, New York, New York) by a single, high-volume orthopaedic surgeon employing a single prosthesis design (Anatomic Dual Mobility (ADM) Stryker, Mahwah, New Jersey). Patient medical records and radiographs were reviewed to confirm the type of implant used, to identify any preoperative risk factors for dislocation, and any complications. Radiographic analysis was performed to assess for signs of osteolysis or remodelling of the acetabulum. RESULTS: There were 151 patients who met the classification of high-risk according to the inclusion criteria and received DM THA during the study period. Mean age was 82 years old (73 to 95) and 114 patients (77.5%) were female. Mean follow-up was 3.6 years (1.9 to 6.1), with five patients lost to follow-up and one patient who died (for a reason unrelated to the index procedure). One patient (0.66%) sustained an intraprosthetic dislocation; there were no other dislocations. CONCLUSION: At mid-term follow-up, the use of a DM bearing for primary THA in patients at high risk of dislocation provided a stable reconstruction option with excellent radiographic results. Longer follow-up is needed to confirm the durability of these reconstructions.

Dislocation following total hip arthroplasty using dual mobility acetabular components: a systematic review.

AIMS: The aim of this systematic review was to report the rate of dislocation following the use of dual mobility (DM) acetabular components in primary and revision total hip arthroplasty (THA). MATERIALS AND METHODS: A systematic review of the literature according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines was performed. A comprehensive search of Pubmed/Medline, Cochrane Library and Embase (Scopus) was conducted for English articles between January 1974 and March 2016 using various combinations of the keywords "dual mobility", "dual-mobility", "tripolar", "double-mobility", "double mobility", "hip", "cup", "socket". The following data were extracted by two investigators independently: demographics, whether the operation was a primary or revision THA, length of follow-up, the design of the components, diameter of the femoral head, and type of fixation of the acetabular component. RESULTS: In all, 59 articles met our inclusion criteria. These included a total of 17 908 THAs which were divided into two groups: studies dealing with DM components in primary THA and those dealing with these components in revision THA. The mean rate of dislocation was 0.9% in the primary THA group, and 3.0% in the revision THA group. The mean rate of intraprosthetic dislocation was 0.7% in primary and 1.3% in revision THAs. CONCLUSION: Based on the current data, the use of DM acetabular components are effective in minimising the risk of instability after both primary and revision THA. This benefit must be balanced against continuing concerns about the additional modularity, and the new mode of failure of intraprosthetic dislocation. Longer term studies are needed to assess the function of these newer materials compared with previous generations. Cite this article: Bone Joint J 2017;99-B(1 Supple A):18-24.

The knee joint in rheumatoid arthritis.

The knee joint is commonly damaged in polyarticular rheumatoid arthritis. Surgical management depends on the preservation of the articular cartilage and degree of synovitis. Arthroscopic synovectomy is performed in intractable synovitis with cartilage sparing. Technique of total knee replacement is more complex because of bone and soft-tissue damage in rheumatoid arthritis, and complications are more common, particularly infection. Overall, long-term results with knee arthroplasty have been excellent in rheumatoid arthritis, with improved function and reduction in pain in the vast majority of patients.

Blood management in orthopedic surgery.

The orthopedic surgeon has several options available for blood conservation. Preoperative autologous donation (PAD) of blood is a cost-effective measure when the cost of managing transfusion-transmitted infectious disease is considered; overuse and underuse are expensive problems, however. Hemodilution, while used successfully in prostate surgery, is logistically impractical in joint replacement centers. Intraoperative blood salvage, although costly, is useful in orthopedic procedures when the anticipated blood loss is > 1,000 mL. Reinfusion of postoperative drainage that has been filtered and washed is being used in some orthopedic procedures. Studies are under way to determine whether this method of blood conservation alters transfusion requirements. Recombinant human erythropoietin (Epoetin alfa) has a role in elective procedures with significant blood loss, including complex revision joint replacement, bilateral joint arthroplasty, and spinal fusion. Preoperative Epoetin alfa administration enhances preoperative autologous blood collection and increases perioperative red blood cell mass.

Prophylaxis against deep venous thrombosis after total knee arthroplasty. Pneumatic plantar compression and aspirin compared with aspirin alone.

A prospective, randomized study was conducted to assess the efficacy of pulsatile pneumatic plantar compression for prophylaxis against deep venous thrombosis after total knee arthroplasty performed with use of regional anesthesia. One hundred and twenty-two patients (164 knees) who were scheduled to have a unilateral or a one-stage bilateral total knee arthroplasty were separately randomized to be managed with either aspirin alone or the pulsatile pneumatic plantar-compression device and aspirin. The prevalence of deep venous thrombosis was 27 per cent (twenty-two of eighty-one knees) in the group treated with pneumatic plantar compression compared with 59 per cent (forty-nine of eighty-three knees) in the patients managed with aspirin alone (the control group) (p < 0.001). A significant difference was also noted in the group that had had a unilateral arthroplasty (a prevalence of 27 per cent [eleven of forty-one knees] in the group treated with pneumatic plantar compression, compared with 67 per cent [twenty-six of thirty-nine knees] in that treated with aspirin alone; p < 0.006) and in the group that had had a one-stage bilateral procedure (a prevalence of 28 per cent [eleven of forty knees] in the group treated with pneumatic plantar compression, compared with 52 per cent [twenty-three of forty-four knees] in that treated with aspirin alone; p < 0.03). No proximal thrombi were noted in any patient who used the pulsatile pneumatic plantar-compression device, while the prevalence of proximal thrombosis in the popliteal or femoral veins was 14 per cent (twelve of eighty-three knees) in the group treated with aspirin alone (p < 0.0003). In the group treated with a unilateral procedure and aspirin alone the prevalence of proximal thrombosis was 13 per cent (five of thirty-nine knees; p < 0.02), while in the group treated with a bilateral procedure and aspirin alone it was 16 per cent (seven of forty-four knees; p < 0.01). Only in the patients who had had a unilateral procedure was use of the compression device associated with significantly less edema postoperatively than was use of aspirin alone. The change between the preoperative and postoperative circumferences of the thigh and leg was significantly less (9 +/- 4.1 millimeters [mean and standard deviation] less for the thigh [p < 0.01] and 6 +/- 3.9 millimeters less for the leg [p < 0.049]) with the compression device than with aspirin alone. In addition, there was significantly less mean drainage (98 +/- 61.1 milliliters) in the group treated with a unilateral procedure and pneumatic compression, compared with that treated with a unilateral procedure and aspirin alone (p < 0.041). An internal timer of the compression device was used to assess the compliance of the patient with use of the device, and a relationship between deep venous thrombosis and the total duration of treatment with the device was found. The patients in whom deep venous thrombosis did not develop used the device for a mean of 96 +/- 23.4 hours (range, sixty to 164 hours) postoperatively, or 19.2 +/- 5.1 hours a day, while those in whom thrombosis developed used it for a mean of 67 +/- 21.1 hours (range, twenty-six to 101 hours), or 13.4 +/- 4.3 hours a day (p < 0.001). No untoward effects were noted in any patient who used the device. This study confirms the safety and efficacy of pulsatile pneumatic plantar compression and aspirin compared with aspirin alone and supports the use of mechanical compression for prophylaxis against deep venous thrombosis and for reduction of edema in patients who have had a total knee arthroplasty. In addition, we found a direct relationship between compliance with the use of this device and its efficacy in reducing deep venous thrombosis.

The use of spinal anesthesia for total hip-replacement arthroplasty.

Two hundred and thirty-four total hip replacements in 199 patients performed by one surgeon were reviewed to compare the effects of spinal and general anesthesia. The amount of total blood loss was reduced an average of 600 milliliters in patients under spinal anesthesia. The amounts of operative blood loss, postoperative suction drainage, and blood replacement were also reduced very significantly (p smaller than 0.001). The patients in the two anesthesia groups were similar as to sex, age, body weight, pre-existing medical disease, preoperative medications administered, hip disease, type of prosthesis used, position during surgery, and anticoagulation regimen. The postoperative complications were fewer in the spinal anesthesia group. It is concluded from this study that spinal anesthesia is to be preferred over general anesthesia in patients undergoing total hip replacement.

Treatment of pathological fractures of the hip by endoprosthetic replacement.

In 167 consecutive pathological or impending fractures of the hip treated by endoprosthetic replacement from 1975 to 1978, there was dramatic relief of pain in all patients. Either a long-stem femoral endoprosthesis or a total prosthetic hip was used. The ambulatory status was significantly enhanced in those patients who were able to walk but it was not in the gravely ill. Cementing the prosthesis allowed stabilization of the entire femur as well as resection of diseased bone. The patients had a median survival time of 5.6 months. There were no dislocations, instances of loosening, or failures of the device, and the incidence of deep infection was 1.2 per cent. If the anticipated life of the patient exceeds one month, that constitutes an indication for prosthetic replacement for treatment of a pathological or impending fracture of the hip.

Operative treatment of olecranon fractures. Excision or open reduction with internal fixation.

We reviewed the cases of 107 patients who underwent surgical treatment of an isolated fracture of the olecranon. Fifty-three patients were treated by primary excision and fifty-four, by open reduction and internal fixation by various methods. Static and dynamic strength measurements were obtained from the elbow extensors of twenty-nine patients from these two groups. In the over-all series, the ratings for pain, function, range of motion, elbow stability, and incidence of degenerative joint changes were similar for each group. However, thirteen local complications occurred in the fifty-four patients who had open reduction and two, in the fifty-three who had primary excision. Need for removal of the fixation device led to an additional thirteen procedures in the fixation group. Biomechanical testing demonstrated no significant difference in elbow extensor performance for the two groups.

The effect of intravenous fixed-dose heparin during total hip arthroplasty on the incidence of deep-vein thrombosis. A randomized, double-blind trial in patients operated on with epidural anesthesia and controlled hypotension.

Heparin was given in fixed doses intravenously during unilateral primary total hip-replacement operations in a prospective, double-blind trial to assess the effect on the incidence of deep-vein thrombosis. One hundred and fifty patients were randomly assigned to one of two groups before the operation. Twenty-four patients were excluded from the study, leaving 126 patients. Group I consisted of sixty-six patients who received saline solution intravenously, and Group II comprised sixty patients who received heparin. All patients had epidural anesthesia with controlled hypotension. Fixed doses of heparin were administered five minutes before the operative incision was made and every thirty minutes throughout the operation. Mean arterial pressures were maintained at between fifty and sixty millimeters of mercury in all patients. Ascending venography was done on the seventh day after the operation. The incidence of deep-vein thrombosis was 24 per cent (sixteen of sixty-six patients) in Group I and 8 per cent (five of sixty patients) in Group II; the difference is significant (p = 0.03). The intraoperative loss of blood averaged 220 +/- 79 milliliters in Group I compared with 269 +/- 109 milliliters in Group II. An average of less than one unit of blood was transfused for each patient in each group. Postoperatively, there was no difference between the groups with regard to the amount of drainage that was collected in a Hemovac device or the values for hematocrit.

Salvage and reinfusion of postoperative sanguineous wound drainage. A preliminary report.

Thirty-five patients who were to have posterior spinal arthrodesis, total hip arthroplasty, or total knee arthroplasty were entered into one of two groups: Group A, to receive unwashed, filtered sanguineous drainage from the wound, or Group B, to receive washed, filtered drainage. The purpose of this prospective study was to evaluate the safety, efficacy, and difficulty of reinfusion of washed compared with unwashed drainage that had been salvaged from the wound after an orthopaedic operation. The sixteen patients in Group A received a mean of 475 milliliters of unwashed drainage for each total knee arthroplasty, 427 milliliters for each total hip arthroplasty, and ten milliliters for the one posterior spinal arthrodesis. The complications included immediate hypotension (two patients), hyperthermia (one patient), and hypotension five hours after reinfusion (one patient). The latter patient died, four days after the operation, of a massive myocardial infarction. The nineteen patients in Group B received a mean of 193 milliliters of washed, filtered drainage for each total knee arthroplasty, 203 milliliters for each total hip arthroplasty, and 179 milliliters for each posterior spinal arthrodesis. Salvage and reinfusion of washed drainage from the wound caused no problems in these patients.

Ruptures of the tendo achillis. An objective assessment of surgical and non-surgical treatment.

A comparative study is presented of seventy-nine patients with rupture of the tendo achillis, forty-eight of whom were treated surgically and thirty-one, non-surgically. With one exception, all were healthy, athletic individuals. Twenty-two per cent of the patients had an initial misdiagnosis. The patients treated surgically were more satisfied with the results of their treatment. Strength, power, and endurance as measured on the Cybex II dynamometer revealed that the patients treated non-surgically attained only 72 per cent of normal strength and 70 per cent of normal power and endurance as compared with the surgically treated patients. Wound complications occurred in only two patients and no reruptures occurred in the surgically treated group, whereas there were nine rereptures in the group not treated surgically.

Methylmethacrylate stabilization for enhancement of posterior cervical arthrodesis in rheumatoid arthritis.

Stainless-steel wire, titanium mesh, and perforated titanium sheets and methylmethacrylate were used in conjunction with autogenous iliac-bone grafts to provide immediate stability in difficult or long posterior cervical fusions in eleven patients with rheumatoid arthritis, who were followed for three to 12.5 years. Two surgical techniques, using methylmethacrylate and metal supplementation of a traditional posterior cervical arthrodesis, are described. One technique includes the occiput, while the other consists of a long posterior fusion that excludes the occiput. In ten of the eleven patients, permanent radiographic stability was maintained as well as a significant reduction of pain and resolution of neural dysfunction. In the eleventh patient a cervical subluxation developed at the distal end of the rigidly fused segment, and eventually the patient died. Four patients who were seen early in the series had wound dehiscences, two of which were infected. Subsequently the methacrylate-metal composite was reduced in volume, and this problem did not recur. In summary, this technique has provided immediate internal splinting and avoided bulky external-fixation devices. It was most useful in fusions of the occiput to the upper part of the cervical spine, in long posterior cervical arthrodesis, and for the repair of pseudarthroses when traditional arthrodesis techniques had failed.

The double-stemmed silicone-rubber implant for rheumatoid arthritis of the first metatarsophalangeal joint. Long-term results.

Sixty-seven feet in forty-five patients who had rheumatoid arthritis were followed for an average of six years (range, four to ten years) after an operation on the forefoot that included resection of the metatarsophalangeal heads or joints and the insertion of a double-stemmed silicone-rubber implant in the first metatarsophalangeal joint. There were forty-two women and three men, and the average age at the time of the operation was fifty-six years (range, thirty-six to seventy-nine years). The mean duration of known rheumatoid arthritis was fifteen years (range, three to thirty-seven years). Resection of the metatarsophalangeal heads or joints was performed through a plantar approach in forty-one feet and a dorsal approach in twenty-six feet. A double-stemmed silicone-rubber implant was placed in the first metatarsophalangeal joint in all feet. Each patient was evaluated clinically and radiographically with use of a foot-scoring system that was developed for this study. The results were assessed for relief of pain, ability to walk (including the use of shoes), presence of calluses or deformity, and radiographic findings. The average preoperative foot score was 47 points; the score had improved to an average of 81 points at the latest follow-up examination. A good or excellent result was obtained in fifty-eight feet (87 per cent). Complications were infrequent. In three feet, there was delayed healing of the wound; three implants were removed because of dislocation and infection; and four feet had revision to correct deformities of the lesser toes.

The prevalence of deep venous thrombosis after total hip arthroplasty with hypotensive epidural anesthesia.

A prospective, randomized trial was done to evaluate the prevalence of deep venous thrombosis following primary unilateral or bilateral total hip arthroplasty with use of hypotensive epidural anesthesia, external pneumatic-compression boots, and aspirin (Group I) and with use of hypotensive epidural anesthesia and aspirin (Group II). All operations were performed by two of us (E. A. S. and T. P. S.) through a posterolateral approach. Two hundred and thirty-one patients who were more than thirty-nine years old and who had a total of 250 primary total hip arthroplasties were included in the study. There were 113 patients (124 hips) in Group I and 118 patients (126 hips) in Group II. All patients had venography on the sixth, seventh, or eighth postoperative day. Group I had no proximal thrombi, seven distal thrombi (6 per cent), and one late pulmonary embolus (1 per cent). Group II had one proximal thrombus (popliteal) (1 per cent), eight distal thrombi (6 per cent), and one late pulmonary embolus (1 per cent). The difference was not significant (p = 0.65). However, a significant difference may have been noted if the study population had been larger. The combination of hypotensive epidural anesthesia and aspirin is effective prophylaxis against deep venous thrombosis in patients who have a primary total hip arthroplasty. The extremely low rate of deep venous thrombosis in the present study may be attributed to the use of hypotensive epidural anesthesia and the associated decrease in blood loss and transfusion requirements.(ABSTRACT TRUNCATED AT 250 WORDS)

Total knee arthroplasty in hemophilia.

Twenty-four total knee arthroplasties were performed in fourteen disabled patients with hemophilia. The average age of the patients at operation was thirty-five years. Twenty-one of the implants that were used were total condylar prostheses. Using The Hospital for Special Surgery knee-rating system after two to nine years of follow-up, the result in fifteen knees was rated as excellent; in six, as good; and in one, as fair. Two patients had a poor result that was attributable to late infection. Pain and function were markedly improved, and the average gain in range of motion was 23 degrees. Postoperative complications, in addition to the infections, included one subcutaneous hematoma, one hemolytic anemia, and one instance of inhibition to Factor VIII. The technical problems in treatment were formidable. Total knee arthroplasty in a hemophiliac can be successful, but it should be performed only with strict hematological supervision. The surgeon should be prepared to treat many potential postoperative complications.

Dislodgment of polyethylene liners in first and second-generation Harris-Galante acetabular components. A report of eighteen cases.

BACKGROUND: Dislodgment of the polyethylene liner is an increasingly common complication following total hip arthroplasty. The purposes of this study are to present the results in a series of patients with this complication and to analyze the mode of failure. METHODS: Between November 1995 and January 2001, eighteen patients who had had a total hip arthroplasty presented with dislodgment of the polyethylene liner from a Harris-Galante metal acetabular shell. The medical records, radiographs, operative notes, and retrieved components were reviewed. In addition, scanning electron microscopy was used to study the fractured surfaces in a shell that had four broken tines. RESULTS: The components had been in situ for an average of seven years (range, three to eleven years). Seventeen components were second generation, and one was first generation. Symptoms developed spontaneously in sixteen patients, during sexual intercourse in one, and following a fall on the hip in one. Radiographs showed eccentric positioning of the head in all of the hips and broken tines in six. All of the shells were well fixed. Treatment consisted of revision of the shell in four patients, exchange of the liner in four, cementation of a new liner into the shell in seven, and cementation of an all-polyethylene cup in three. The liners had severe damage of the rim. Scanning-electron microscopy of the fractured surfaces of four tines revealed a fatigue pattern. CONCLUSIONS: We believe that, as the liner wears and becomes loose because of an inadequate locking mechanism, progressive micromotion occurs and the load increases on the polyethylene rim until it deforms and/or fractures. Subsequently, nothing prevents the liner from rotating out of the shell. As this mechanism of failure appears to include fatigue failure of the locking tines and wear of the liner, this complication is likely to increase as the components age in situ.

Patients' expectations of knee surgery.

BACKGROUND: Patients' expectations of medical care are linked to their requests for treatment and to their assessments of outcome and satisfaction. Our goals were to measure patients" preoperative expectations of knee surgery and to develop and test patient-derived knee expectations surveys. METHODS: An initial sample of 377 patients (mean age, 54.6 18.2 years; 52% women) was enrolled in the survey-development phase. One hundred and sixty-one (43%) of these patients subsequently underwent total knee arthroplasty; seventy-five (20%), cruciate ligament repair; eighty-five (23%), meniscal surgery; and fifty-six (15%), surgery for another knee condition. Preoperatively, these patients were asked open-ended questions about their expectations of knee surgery. Their responses were grouped with use of qualitative research techniques to generate categories of expectations. Categories were transformed into specific questions and were formatted into two draft surveys, one for patients undergoing total knee arthroplasty and one for patients undergoing other surgical procedures on the knee. A second sample of 163 patients (mean age, 55.1 17.5 years; 49% women) was enrolled in the survey-testing phase, and they completed the draft surveys on two separate occasions to establish test-retest reliability. Items were selected for the final surveys if they were cited by 5% of the patients, if they represented important functional changes resulting from surgery, or if they represented potentially unrealistic expectations. All selected items fulfilled reliability criteria, defined as a kappa (or weighted kappa) value of 0.4, or were deemed to be clinically relevant by a panel of orthopaedic surgeons. RESULTS: From the survey-development phase, a total of fifty-two categories of expectations were discerned; they included both anticipated items such as pain relief and improvement in walking ability and unanticipated items such as improving psychological well-being. Expectations varied by diagnosis and patient characteristics, including functional status. Two final surveys were generated: the seventeen-item Hospital for Special Surgery Knee Replacement Expectations Survey and the twenty-item Hospital for Special Surgery Knee Surgery Expectations Survey. Each required less than five minutes to complete. CONCLUSIONS: Patients have multiple expectations of knee surgery in the areas of symptom relief and improvement of physical and psychosocial function, and these expectations vary according to the diagnosis. We developed two valid and reliable surveys that can be used preoperatively to direct patient education and shared decision-making and to provide a framework for setting reasonable goals. Reexamining patients' responses postoperatively could provide a way to assess fulfillment of expectations, which is a crucial patient-derived measure of outcome and satisfaction.

The effect of preoperative donation of autologous blood on deep-vein thrombosis after total hip arthroplasty.

We have assessed the effect of the donation of autologous blood and the preoperative level of haemoglobin on the prevalence of postoperative thromboembolism in 2043 patients who had a total hip arthroplasty. The level of haemoglobin was determined seven to ten days before surgery and all patients had venography of the operated leg on the fifth postoperative day. The number of patients who had donated autologous blood (1037) was similar to that who had not (1006). A significant decrease in the incidence of deep-vein thrombosis (DVT) was noted in those who had donated blood preoperatively (9.0%) compared with those who had not (13.5%) (p = 0.003). For all patients, the lower the preoperative level of haemoglobin the less likely it was that a postoperative DVT would develop. Of those who had donated blood, 0.3% developed a postoperative pulmonary embolism compared with 0.7% in those who had not, but this difference was not statistically significant. No significant difference was found in the requirements for transfusion between the two groups.

Venous haemodynamics after total knee arthroplasty: evaluation of active dorsal to plantar flexion and several mechanical compression devices.

We performed a crossover study to evaluate the haemodynamic effect of active dorsal to plantar flexion and seven pneumatic compression devices in ten patients who had a total knee arthroplasty. Using the Acuson 128XP/10 duplex ultrasound unit with a 5MHz linear array probe, we assessed the augmentation of peak venous velocity and venous volume above and below the junction of the greater saphenous and common femoral veins in order to study both the deep and superficial venous systems. The pneumatic compression devices evaluated included two foot pumps (A-V Impulse System and PlexiPulse Foot), a foot-calf pump (PlexiPulse Foot-Calf), a calf pump (VenaFlow System) and three calf-thigh pumps (SCD System, Flowtron DVT and Jobst Athrombic Pump). The devices differed in a number of ways, including the length and location of the sleeve and bladder, the frequency and duration of activation, the rate of pressure rise, and the maximum pressure achieved. A randomisation table was used to determine the order of the test conditions for each patient. The enhancement of peak venous velocity occurred primarily in the deep venous system below the level of the saphenofemoral junction. The increases in peak venous velocity were as follows: active dorsal to plantar flexion 175%; foot pumps, A-V Impulse System 29% and PlexiPulse 65%; foot-calf pump, PlexiPulse, 221%; calf pump, VenaFlow, 302% and calf-thigh pumps, Flowtron DVT 87%, SCD System 116% and Jobst Athrombic Pump 263%. All the devices augmented venous volume, the greatest effect being seen with those incorporating calf compression. The increases in ml/min were found in the deep venous system as follows: foot pumps, A-V Impulse System 9.6 and PlexiPulse Foot 16.7; foot-calf pump, PlexiPulse, 38.1; calf pump, VenaFlow, 26.2; calf-thigh pumps, Flowtron DVT 61.5, SCD System 34.7 and Jobst Athrombic Pump 82.3. Active dorsal to plantar flexion generated 8.5 ml for a single calf contraction.