The extensile rectus snip exposure in revision of total knee arthroplasty.

Revision of a total knee arthroplasty may require an extensile approach to permit a satisfactory exposure without compromising the attachment of the patellar tendon. It has been assumed that a rectus snip is a relatively benign form of release, but the effect of using this approach on function, pain and patient satisfaction is not known. From January 1997 to December 1999, 107 patients who underwent revision of total knee arthroplasty were followed up at a minimum of two years (mean 40.5 months) and assessed by the Oxford Hip Score, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Short-Form (SF)-12 and patient satisfaction. Co-morbidity, surgical exposure, the Hospital for Special Surgery (HSS) knee scores and the range of movement were also used. A standard medial parapatellar approach was used in 57 patients and the rectus snip in 50. The two groups were equivalent for age, sex and co-morbidity scores. The WOMAC function, pain, stiffness and satisfaction scores demonstrated no statistical difference. The use of a rectus snip as an extensile procedure has no effect on outcome.

Arterial complications and total knee arthroplasty.

Arterial complications after total knee arthroplasty (TKA) are rare; however, the sequelae can be disastrous. Infection and the need for amputation or vascular reconstructive surgery are not uncommon. A thorough preoperative assessment can identify at-risk patients, many, if not all, of whom have preexisting peripheral arterial disease. In the presence of peripheral arterial disease, the use of a tourniquet during TKA has been implicated in subsequent arterial complications. Following the guidelines that have been established regarding preoperative assessment, the role of the vascular surgeon, and the use of a tourniquet before and during TKA can assist the orthopaedic surgeon in assessing candidates for TKA and reducing the risk of arterial complications.

The PROSTALAC functional spacer in two-stage revision for infected knee replacements. Prosthesis of antibiotic-loaded acrylic cement.

The PROSTALAC functional spacer is made of antibiotic-loaded acrylic cement but has a small metal-on-polythene articular surface. We have used it as an interim spacer in two-stage exchange arthroplasty for infected total knee replacement. PROSTALAC allows continuous rehabilitation between stages as it maintains good alignment and stability of the knee and a reasonable range of movement. It also helps to maintain the soft-tissue planes, which facilitates the second-stage procedure. We reviewed 45 consecutive patients, treated over a period of nine years. The mean follow-up was for 48 months (20 to 112). At final review, there was no evidence of infection in 41 patients (91%); only one had a recurrent infection with the same organism. There was improvement in the Hospital for Special Surgery knee score between stages and at final review. The range of movement was maintained between stages. Complications were primarily related to the extensor mechanism and stability of the knee between stages. Both of these problems decreased with refinement of the design of the implant. The rate of cure of the infection in our patients was similar to that using other methods. Movement of the knee does not appear to hinder control of infection.

The outcome of two-stage arthroplasty using a custom-made interval spacer to treat the infected hip.

Sixty-one patients undergoing a two-stage revision of an infected hip using a prosthesis of antibiotic-loaded acrylic cement were followed for an average of 43 months. Twelve patients were excluded (3 died, 6 had no proven infection, and 2 no second stage). Only 1 patient was lost to follow-up evaluation from those included, for a retrieval rate of 98% for those still living. Of the remaining 48 patients, 3 had further sepsis: Two became reinfected with different organisms and 1 with the same organism, for an infection eradication rate of 94%. The other 45 had no clinical, laboratory, or radiographic evidence of infection. Thirty-seven patients (80%) had a Harris hip score greater than 80 or an improvement of at least 30 points.

Position of the knee joint after total joint arthroplasty.

A method for assessing knee joint position after surgery using the preoperative long-leg radiograph and the postoperative knee radiograph is described. Assessment of the formula has shown a near perfect correlation between the calculated position on the long-leg radiograph compared with the measured position for 44 knees. Three hundred eighteen knees after total joint arthroplasty were retrospectively reviewed and the postoperative position was determined. The preoperative position of the mechanical axis was 14.5 +/- 37.3 mm medial to the knee joint center. Using the standing knee radiograph the postoperative position of the mechanical axis was 3.07 +/- 9.2 mm lateral to the knee joint center, while the portable radiograph placed the mechanical axis 4.5 +/- 12.4 mm medial to the knee joint center. There was a highly significant difference in the position of the knee joint center depending on the radiograph used for calculation (standing or portable). The difference between the two means was not due to opening of the knee joint, but likely due to change in the rotation of the knee in the presence of knee flexion. This series of the knee arthroplasties has a low projected rate of aseptic failure.

Robotrac in total knee arthroplasty. The silent assistant.

This article describes a new prerobotic device (Robotrac) that may be used effectively in total knee arthroplasty (TKA). This device holds the femur in any position, allowing the surgeon to situate the knee in any position of flexion that may be necessary during the course of TKA. Using this device, it often is possible to perform TKA without any additional assistant surgeons. To date, we have used Robotrac in more than 200 consecutive total knee replacements without any untoward effects. With the use of this device, it is possible to save about $142 Canadian per total knee replacement. The literature concerning the use of robotics in medicine is reviewed.

Temporary antibiotic loaded acrylic hip replacement: a novel method for management of the infected THA.

Postoperative infection after hip joint replacement is an uncommon but potentially devastating complication in contemporary orthopaedics. Management in two stages is the more favored approach in North America. This introduces difficulty with patient management in the interval between stages, delays rehabilitation, and introduces technical difficulty during the second stage. A method has been developed whereby a temporary antibiotic-loaded facsimile of the hip is introduced at the first stage, designed to maintain stability of the joint, length of the limb, and mobility of the patient. It has been used in a total of 86 cases to date. The results in 46 cases with a minimum follow-up of 2 years are reviewed in this article. The infection was controlled in 93.5% of cases.

Two-stage exchange arthroplasty using a functional antibiotic-loaded spacer in the treatment of the infected knee replacement: the Vancouver experience.

Two-stage exchange arthroplasty is currently the method of choice in the treatment of the infected knee replacement. The prosthesis of antibiotic-loaded acrylic cement (PROSTALAC) is a temporary, antibiotic-loaded functional prosthesis that is used as an interim spacer in two-stage exchange arthroplasty. In this prospective series, we report on the early results of the use of the PROSTALAC knee spacer in two-stage exchange arthroplasty of infected knees. A total of 24 knees were treated with this prosthesis, and were reviewed at a mean follow-up time of 2.2 years. Infection was controlled in all but 2 knees, for an infection cure rate of 91.7%. The patients' function was improved between stages, and motion was maintained in the majority of cases. The significant complications with the PROSTALAC implant in place were tibio-femoral instability, which was corrected with a design modification, and patellar instability, which continues to be a problem. These complications were transient and were not of any significance after the second stage.

Occlusion of arterial flow in the extremities at subsystolic pressures through the use of wide tourniquet cuffs.

Tourniquet-induced peripheral neuropathy is at least partially attributable to excessive forces applied to the nerves beneath cuffs inflated to high pressures. Lowering the inflation pressure to the minimum necessary to obtain an effective arrest of blood flow distal to the tourniquet cuff should increase the safety of these systems. Tourniquet cuffs with widths varying from 4.5 cm to 80 cm were applied to the upper and lower extremities of 34 healthy, normotensive volunteers. Occlusion pressure for the arterial system under study was estimated by determining that level of cuff inflation at which the distal pulse became detectable by ultrasonic flowmetry. The occlusion pressure was inversely proportional to the ratio of tourniquet cuff width to limb circumference and was in the subsystolic range at a cuff width to limb circumference ratio above 0.5. Wide tourniquet cuffs can achieve an effective arrest of the regional arterial circulation at subsystolic pressures of inflation. Wide cuffs may reduce the risk of tourniquet-induced injury to underlying soft tissues by lowering the inflation pressure required to secure a bloodless field.

Perineural pressures under the pneumatic tourniquet in the upper extremity.

The literature indicates that tourniquet-induced neurological injuries are relatively common and frequently occur at a subclinical level. In order to evaluate the pressure transmitted to the major peripheral nerves of the arm by an externally applied pneumatic tourniquet, a fully implantable biomedical pressure transducer was placed adjacent the radial, median and ulnar nerves in six cadaver upper extremities of average dimensions. This sensor allowed accurate, reproducible measurements of perineural pressures without requiring significant disruption of the normal anatomical structures of the test limb for its installation. At levels of tourniquet cuff inflation which are commonly used in clinical practice, there was little or no decrease in the pressure detected in the perineural regions over that applied to the surface of the limb. In addition, there was a steep gradient of perineural pressure between locations beneath the edge of the cuff and those under its midpoint. This was most marked at the highest levels of tourniquet inflation. At presently accepted levels of inflation, pneumatic tourniquet cuffs transmit high pressures to the peripheral nerves without any significant attenuation by the intervening soft tissues. The distribution of these forces is one which may subject the underlying nerves to deleterious shear forces, especially at higher levels of inflation.

Massive intrapelvic synovial cyst as a complication of total hip replacement arthroplasty: a case report.

The authors report a case of massive intrapelvic synovial cyst complicating total hip arthroplasty in a 35-year-old woman with rheumatoid arthritis. The clinical presentation raised the possibility of a coincidental soft-tissue malignant tumour. This was ruled out by ultrasonography, computed tomography, fine-needle aspiration with examination of cells and culture and, ultimately, by image intensification in the operating room during aspiration of the cyst and injection of the adjacent hip joint with Hypaque. The authors conclude that perforation of the acetabular floor at total hip arthroplasty was likely the precipitating event. After 1 year there was no indication for surgical excision of the cyst.

New finger cuffs for use with digital tourniquets.

The advent of tourniquets employing digital technology has led to significant improvements in the safety and accuracy of surgical procedures performed with an occlusive cuff applied proximally on a limb. This article describes the evaluation of new cuffs used on fingers that may permit significantly lower pressures to be more safely and consistently employed. Our experimental studies would suggest that finger occlusion pressure is a function of cuff design, cuff width, finger circumference, and systolic blood pressure.

Introduction to microsurgery.

PIP: An updated definition of microsurgery includes the application of magnification techniques to basic surgical principles and the functional restoration of body structures by means of the direct union of parts or transfer of tissue using microsurgical techniques. Nylen performed the 1st surgery under magnification with the use of an operating microscope in Sweden in 1921. With the expanding scope of microsurgery, it becomes obvious that it is a surgical technique clinically applicable in every surgical specialty. The equipment for microscopy is microscopes, sutures, jeweler's forceps, needle holders, scissors, and coagulators. In microsurgery, all surgical movements have been reduced to a pinch mechanism between thumb and index. The instruments have been designed with this in mind and are characterized by small precision tips, light balanced proportions, pinch closure, and nonreflective surfaces. Long handled instruments are necessary for neurosurgery and gynecology due to the depth of the working field. The perfection of the microsurgery technique begins with extensive practice in the research laboratory. Clinical microsurgical reconstruction should be attempted only when competence has been achieved in the laboratory.^ieng