[Special surgical technique of minimally invasive total knee replacement]. / Spezielle chirurgische Technik der minimalinvasiven Totalendoprothetik des Kniegelenkes.

AIM: Due to the initial disappointing experience with minimally invasive knee arthroplasty, many surgeons still prefer the conventional technique. Sharing technical details, personal insights and results may help abbreviate the individual learning curve towards successful MIS. METHOD: Based on the experience of over 250 minimally invasive knee arthroplasties an operative algorithm was developed and evaluated to assure optimal realization of a gentle joint replacement using a mini-mid-vastus incision. Short-term results were compared to those of the conventional technique with particular regard to pain, use of analgesic medication, flexion of the knee and achievements at physiotherapy. RESULTS: In comparison to the conventional procedure, MIS produced significantly better results regarding pain and function during early rehabilitation and did not affect the perfect positioning of the implants. The morphine-equivalent dose was less than a half on day 2 after operation. Flexion on days 1 and 3 was 70 degrees and 75 degrees respectively. 80 degrees were obtained after 4 days and after 6 weeks flexion was at an average of 115 degrees . In contrast, results of the conventional control group were notably worse, with 50 degrees and 65 degrees on days 1 and 3, 80 degrees being obtained on day 6 only and a mean flexion of 100 degrees after 6 weeks. CONCLUSION: The special surgical technique of minimally invasive knee arthroplasty accelerates and facilitates the rehabilitation of the patient and thereby defines a new quality standard.

Unicompartmental knee replacement: some unanswered questions.

Within the past 5 years, there has been a resurgence of interest in doing unicompartmental knee replacement, which was encouraged by reports of easier recuperation, decreased hospital stays, and good functional results. Before doing a unicompartmental replacement, the surgeon should answer four important questions: Is the disease truly unicompartmental? Can this be determined on a clinical examination and standard radiographs, or are more sophisticated studies such as a bone scan or an arthroscopy required? Second, if the patient does have unicompartmental disease are there any specific contraindications to the surgery? The absence of an intact anterior cruciate ligament, and presence of an inflammatory arthroplasty have been said to be contraindications. Is crystalline arthropathy a contraindication? What are the limits of fixed deformity in varus or flexion that can be corrected by a unicompartmental replacement? Overcorrection of angular deformities has in the past led to increased wear of the opposite compartment. Therefore, how much should the knee be corrected? What surgical technique should the surgeon consider? Should the tibial components be inset into the bone or onset. Although it has been alleged that instrumentation is not necessary, obtaining proper alignment often cannot be obtained without the use of instruments. Finally, should the implants be inserted with or without acrylic cement, and what is the minimal polyethylene thickness that is permissible?

Lateral release rates after total knee arthroplasty.

For a total knee replacement to function well, the patella must track centrally in the trochlear groove. A lateral release may be required to ensure such central tracking. During surgery, an evaluation was made of patellar tracking in 178 patients undergoing total knee replacement. The Genesis II prosthesis with a deep-dish tibial insert was used for all the patients. The evaluation was made using the nontouch technique and the axial traction (modified no-touch) technique before and after release of the tourniquet. With the tourniquet still inflated, there were 29 knees in which the patella tilted laterally and 11 additional knees in which the patella subluxed laterally. Using the modified no-touch technique, there were only 12 knees in which the patella tilted laterally and five in which it subluxed laterally. With the tourniquet deflated, only nine of the patellas tilted laterally and three subluxed laterally. It was only in this final group that a lateral release was done for an overall lateral release rate of 6%. Eleven of these 12 knees had a preoperative fixed valgus deformity greater than 10 degrees. Only one lateral release was required for a patient with a preoperative varus deformity. Four patients with a preoperative fixed valgus deformity and a laterally subluxed patella did not require a lateral release. Axial realignment and reconstitution of an anterior trochlear surface by the implant were sufficient to centralize the patella. Had only the no-touch test been used, there would have been 18 unnecessary lateral releases done. When the knees were evaluated radiographically, there was no statistical difference in patellar position between that group and the knees that required a lateral release. Overall in the entire group at 6 weeks after surgery, 105 knees (59%) had no patellar tilt. At 3 months, as quadriceps tone returned to normal, 138 knees (79%) had no patellar tilt. Thirty-three of the remaining 35 knees had a patellar tilt less than 10 degrees. None of the patients had lateral patellar subluxation at any time after surgery.

The Genesis total knee prosthesis: a 10-year followup study.

This current author reports on the results of 100 consecutive patients with osteoarthritis who underwent a primary cemented total knee replacement using the Genesis prosthesis and who have been followed up for at least 10 years after surgery. In patients in whom the posterior cruciate ligament was sacrificed (combined flexion and angular deformities > 15 degrees to 20 degrees) a posterior-stabilized cam module was affixed to the femoral component and a posterior-stabilized polyethylene was used. More than 95% of patients in both groups had excellent pain relief. The mean flexion was 114 degrees in the group of patients in whom the posterior cruciate ligament was sacrificed and 117 degrees in the group of patients in whom the posterior cruciate ligament was retained. Partial bone cement tibial radiolucencies were seen in 12% of the patients in whom the posterior cruciate ligament was retained and 2% of the patients in whom the posterior cruciate ligament was sacrificed. At 10 years, 76% of the group in whom the posterior cruciate ligament was retained had excellent results and 20% had good results. In the group in whom the posterior cruciate ligament was sacrificed 75% had excellent results and 23% had good results. The survivorship was 96% in the group of patients in whom the posterior cruciate ligament was retained and 97% in the group of patients in whom the posterior cruciate ligament was sacrificed.

Deep-dish congruent tibial component use in total knee arthroplasty: a randomized prospective study.

One hundred seventy-six patients with osteoarthritis of the knee were randomized prospectively into two groups. In both groups the posterior cruciate ligament was released from its femoral attachment. In one group a posterior stabilized tibial component was used whereas in the other group a deep-dish tibial polyethylene component was inserted (Genesis II). The surgical and perioperative technique was identical in both groups and all the implants were cemented to their respective bones. Patients began range of motion exercises within the first few hours after surgery and were allowed weightbearing to tolerance beginning on the first postoperative day. At followup there was no statistical difference in the mean range of flexion (approximately 116 degrees), ability to ascend and descend stairs in a bipedal manner (80%), pain scores, knee scores (94 points), stability, or the lack of anterior knee pain. Postoperative implant alignment in the sagittal and coronal planes and on Merchant skyline views was excellent in both groups. There was only one lateral release required and that was in one patient who received a deep-dish component. Using deep-dish implant obviates the need to resect intercondylar femoral bone, decreasing the potential for fracture and maximizing bone volume should revision be necessary in the future.

Rotating hinge total knee arthroplasty in severly affected knees.

A consecutive series of 24 knees in 21 patients who received a Finn rotating hinge for primary (nine knees) or revision (15 knees) total knee arthroplasty between August 1993 and January 1997 was reviewed. The average followup was 33 months (range, 21-62 months) for all patients in the study. Seventeen patients (20 knees) were followed up for more than 2 years. Twenty-four knees (21 patients) were categorized according to Knee Society scoring criteria: 37.5% (nine knees) were Category A, 25% (six knees) were Category B, and 37.5% (nine knees) were Category C. Using the Knee Society knee and function scores, clinical and radiographic results were assessed and outcome analysis was determined. The average Knee Society knee score improved from 44 points (range, 5-64 points) before surgery to 83 points (range, 45-95 points) after surgery; the average functional score according to the Knee Society system improved from 10 points (range, 0-35 points) before surgery to 45 points (range, 0-100 points) after surgery. Pain and function markedly improved after surgery. For treatment of the most severely affected knees with compromised bone and ligamentous instability, the Finn total knee replacement appears to be an acceptable option. As a rotating hinge design, the prosthesis at early followup provides excellent pain relief, restoration of walking capacity, and stabilization, without evidence of early mechanical failure.

Total knee replacement in patients older than 85 years.

Between 1987 and 1995, 62 unilateral total knee replacements performed in patients older than 85 years (mean age, 87 years) were followed up for a minimum of 2 years (range, 2-11 years, mean, 5.4 years). This group represented 3.8% of all the total knee replacements performed during the same time. The majority of the patients were women with osteoarthritis. There was a 70% preoperative cardiac disease comorbidity. Overall, confusion after surgery was greater in this older group than in the patients younger than 85 years of age, however, confusion was lower in the group of patients who had epidural anesthesia as compared with those patients who had surgery under general anesthesia. The mean knee score at followup was 89 points and the mean pain score was 43 points (of 50 points). The mean flexion was 114 degrees. Seventy-five percent of these elderly patients still required the use of a cane for walking outdoors compared with 18% of the patients who were younger than 85 years. More than 855 of the older patients could travel independently to socialize and shop after surgery. Seventy-six percent of the patients were living independently or in senior retirement housing after surgery. Only two of the patients required living accommodations in a nursing home. One third of the patients still could drive their own car after surgery. Quality of life improvement was markedly increased in this elderly group of patients. The results of this study indicate that total knee replacement still is a valuable procedure even for this elderly group, and most of these patients returned to a more functional lifestyle.

Total knee replacement for patients with patellofemoral arthritis.

Fifty-three patients with incapacitating patellofemoral arthritis and minimal tibiofemoral changes underwent a total knee replacement. Their results were compared with the results of a concomitant series of patients with tricompartmental osteoarthritis. Preoperatively group of patients with patellofemoral arthritis had more individuals with a lateral patellar tilt and inability to climb stairs in a bipedal manner than in the group with tricompartmental arthritis. Furthermore, fewer patients in the group of patients with patellofemoral arthritis could rise independently from a chair than could those patients with tricompartmental arthritis. The mean followup period was 7.4 years. The rate of lateral parapatellar releases was three times greater in the patients with patellofemoral arthritis. The group of patients with patellofemoral arthritis had higher knee scores and a greater ability to climb stairs in a bipedal manner as compared with the patients with tricompartmental arthritis. Residual anterior knee pain was present in approximately 7% of patients in both groups. Total knee replacement resulted in better outcomes for older patients with patellofemoral arthritis as compared with patellofemoral replacement, debridement procedures, and patellectomy.

Management of the patella during revision total knee replacement arthroplasty.

Managing the patella and balancing the patellofemoral joint space is one of the most difficult aspects of performing a primary total knee replacement (TKR). The situation is compounded in the revision situation. Unfortunately, an otherwise well-performed TKR will fail because of problems with the patella or the extensor mechanism. This article discusses various aspects of the management of the patella and extensor mechanism during revision TKR with an objective of minimizing complications and maximizing functional outcomes. The topics covered include exposure of the patella and extensor mechanism during revision surgery, whether or not to remove all prior patellar implants, the technique for removal of a prior implant, the management of bone loss or fractures of the patella during revision TKR, the insertion (or noninsertion) and fixation of a new implant, and the balance of the patellofemoral joint space, including avoidance of patella baja or patella alta. A compilation of scientific and "no-so" scientific data and experience gleaned over the past 26 years of total knee replacement surgery will be presented.

Ultrasound screening for deep venous thrombosis after total knee arthroplasty. 2-year reassessment.

The efficacy of ultrasound compared with ascending venography for the detection of deep venous thrombosis immediately after total knee arthroplasty was assessed after a 2-year interval. One hundred thirty-seven patients were eligible for the study; however, 31 patients received only one of the screening methods and a color Doppler examination was inconclusive in six patients. Therefore, 100 patients had a Doppler examination and a venogram. Overall, the sensitivity of ultrasound was 85%, the specificity 97%, the positive predictive value 85%, the negative predictive value 97%, and the accuracy 95%. The sensitivity in the calf was 83%, in the popliteal vein 86%, and in the femoral vein 100%. Two years ago, the initial assessment of ultrasound for the detection of deep venous thrombosis after surgery in patients who had total joint arthroplasty revealed a 75% sensitivity, 99% specificity, 91% positive predictive value, 97% negative predictive value, and 97% accuracy. The sensitivity in the calf was 83%; the sensitivity in the popliteal vein was 40%; and the sensitivity in the femoral vein was 50%. After 2 years of using this screening test with one technician and one radiologist, an improvement with this noninvasive technique was shown. However, it was found that Doppler imaging is not as sensitive as venography for detecting calf thrombi. Any imaging technique should be validated by each institution to determine the validity of the instrument and the learning curve of the technician administering the examination.

Comparison of joint position sense after total knee arthroplasty.

A comparison of joint position sense, determined by reproducibility of index angles and their subsequent change, was performed in 55 knees that had undergoing a semiconstrained total knee arthroplasty. Knees were stratified into groups that represented arthroplasties performed with or without posterior cruciate ligament retention, with or without resurfacing of the patella, and with or without cement for fixation. There was no significant difference in joint position sense among all the arthroplasty groups. Likewise, there was no difference in joint position sense between any of the arthroplasty groups and an age-matched control group of 32 knees in 32 patients who had not previously undergoing a total knee arthroplasty. Knee arthroplasty does not affect joint position sense.

The Insall Award. Total knee replacement with posterior cruciate ligament retention in rheumatoid arthritis. Problems and complications.

A series of patients with rheumatoid arthritis underwent total knee replacement with posterior cruciate ligament retention and was observed a minimum of 6 years and a mean of 8.2 years. A group of patients with osteoarthritis with an identical prosthesis and a group of patients with rheumatoid arthritis with a posterior stabilized implant served as controls. In the rheumatoid arthritis group with posterior cruciate ligament retention, there was an increased incidence in posterior instability and recurvatum deformity, resulting in an increased revision rate. Those patients undergoing revision for instability had a higher incidence of recurrent synovitis, and at revision the posterior cruciate ligament was grossly absent with a Grade 1 synovial reaction. In patients with rheumatoid arthritis undergoing total knee replacement, a posterior stabilized prosthesis rather than a posterior cruciate ligament sparing prosthesis should be used.

The Insall Award. Total knee replacement with posterior cruciate ligament retention in patients with a fixed varus deformity.

A group of patients with a preoperative varus contracture of at least 15 degrees underwent total knee replacement with retention of the posterior cruciate ligament. Their outcomes at 10 years were compared with a group of patients with similar contractures in whom a posterior stabilized implant was used, and to a group of patients in whom there was no contracture. In the contracture group where the posterior cruciate ligament was retained, there was an increased incidence of pain, an increased incidence of bone cement radiolucencies, and a decrease in the eventual flexion arc. There was likewise an increased revision rate and a decreased survivorship. In patients with such contractures, the posterior cruciate ligament is a part of the deformity; the deformity cannot be corrected by medial release procedures alone. All these results suggest that for the patient with a fixed varus contracture a posterior cruciate release should be performed and a posterior stabilized type of implant used.

Knee closure in total knee replacement: a randomized prospective trial.

A randomized prospective study of 75 total knee replacements in 64 patients who were randomized to capsular closure with the knee in full extension or in flexion was done. Thirty-one knees received a posterior cruciate ligament retaining prosthesis and 44 knees received a posterior stabilized prosthesis. Preoperatively, there was no significant difference between the groups, and patients were stratified by surgeon and type of prosthesis. Postoperatively, all patients were evaluated by a physical therapist who did not know the type of prosthesis the patient received. In addition to the range of motion obtained at discharge; the number of days required to achieve unassisted transfer; the number of days required to achieve assisted and unassisted use of a walker, cane, and stairs; and the number of days to discharge from the hospital were recorded. All patients were also evaluated at 2 to 3 months postoperatively, and the Knee Society clinical rating system scores were compared. There was no statistically significant difference in any of the early rehabilitation parameters or in the 2- to 3-month followup data. Moreover, there was no statistically significant difference in the rate of complications. With stratification according to the type of prosthesis used or the surgeon performing the operation, there was still no statistically significant difference in any of the studied parameters. It was therefore concluded that the degree of knee flexion at the time of capsular closure in total knee replacement has no effect on early rehabilitation after total knee replacement.

Randomized trial of epidural versus general anesthesia: outcomes after primary total knee replacement.

To compare the effects of epidural anesthesia and general anesthesia on early postoperative outcomes after unilateral primary total knee replacement, 262 patients were randomly assigned to receive either epidural or general anesthesia. All patients received a common rehabilitation protocol including a standardized assessment of progress. One hundred eighty-eight patients received a common thromboembolic prophylaxis protocol with postoperative aspirin, and had a standardized surveillance protocol to detect thromboembolic complications. Deep vein thrombosis was determined by venography on the operative limb, and pulmonary embolism was determined by comparison of preoperative and postoperative lung perfusion scans. The epidural anesthesia group reached all rehabilitative milestones earlier postoperatively than did the general anesthesia group, with a statistically significant earlier attainment of stair climbing. The incidence of deep vein thrombosis was 40% with epidural anesthesia, and 48% with general anesthesia. There were no clots proximal to the popliteal veins. The incidence of pulmonary embolism on lung scan was 12% with epidural anesthesia and 9% with general anesthesia. Epidural anesthesia is associated with more rapid achievement of postoperative in hospital rehabilitation goals after total knee replacement. A minor reduction in postoperative deep vein thrombosis rate was observed with epidural anesthesia, but this did not reach statistical significance. No difference in early postoperative pulmonary embolism was observed between the 2 types of anesthesia.