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Biomedical subjects

A D Hanssen

Publications and source records attributed to A D Hanssen.

At least 55 records · Page 3Linked to original sources
PubMed1997

Differences in patellar tracking and knee kinematics among three different total knee designs.

Patellar complications are the primary reason for reoperation of the current condylar type designs. The aim of this study was to compare patellar tracking of various knee implant designs: Genesis II NexGen, and the P.F.C. Sigma Modular Knee System regarding trochlear groove center curvature. Nine unembalmed whole cadaveric lower extremities were used. The quadriceps and hamstrings were dissected into their individual muscles and loads were applied onto the muscles proximally based on the cross sectional area of the muscles. The three-dimensional kinematics of the patellofemoral and tibiofemoral joint of the intact knee were measured using a 3Space tracking system. Three implants (one from each company) were implanted onto the same cadaveric knee in random order consecutively. This was done to ensure consistency of the soft tissue constraints in influencing the amount of patellar tracking. Patellar rotation, patellar tilting, patellar lateral shift and patellar displacement in relation to groove center were measured. There was no significant difference between the intact knee and the various implants regarding patellar rotation and lateral shift. However, all three prosthetic designs showed a significant degree of lateral tilting when compared with the intact knee. At 60 degrees knee flexion, the normal patella was tilted laterally to 0.44 degree +/- 2.15 degrees as compared with the Genesis II patella at 4.75 degrees +/- 4.81 degrees, the NexGen patella at 4.85 degrees +/- 4.81 degrees, and the P.F.C. Sigma patella at 4.89 degrees +/- 3.79 degrees lateral tilt. There was no difference between the intact knee compared with the resurfaced patella in patellar displacement in relation to the groove center. This study suggests the relatively similar kinematic behavior between the implant designs as compared with the intact knees. However, additional modification of implant geometry may be required to help decrease the amount of patellar tilt.

Arthroplasty, Replacement, Knee↗
PubMed1997

Periprosthetic fractures of the tibia associated with total knee arthroplasty.

One hundred two periprosthetic tibial fractures associated with total knee arthroplasty were identified in 29 men and 73 women. Eighty-three fractures occurred postoperatively, and 19 occurred intraoperatively. Fractures were classified into four types based on location and proximity to the prosthesis. There were 61 Type I fractures, occurring at the tibial plateau; 22 Type II fractures, occurring adjacent to the prosthetic stem; 17 Type III fractures, occurring distal to the prosthetic stem; and two Type IV fractures, involving the tibial tubercle. Fracture types were additionally classified by whether the prosthesis appeared to be radiographically well fixed (A) or loose (B) at the time of fracture, or whether the fracture occurred intraoperatively (C). The majority of postoperative Types I and II fractures were Types IB and IIB, and these were treated most successfully with revision surgery. Types IIA, IIIA, and IVA fractures were managed successfully by the usual principles of tibial fracture treatment. Type IC fractures usually were managed by intraoperative fixation, Type IIC by bone grafting or external immobilization and weightbearing restrictions, and Type IIIC by conventional fracture management. This classification system provides a guide for determining the appropriate treatment for tibial fractures associated with total knee arthroplasty.

Adult↗
PubMed1996

Total knee arthroplasty in a previously ankylosed or arthrodesed knee.

Few reports address the reconstructive challenge of total knee arthroplasty after a surgically fused or ankylosed knee. The long term results and complications of a large series of patients who have had their ankylosed or arthrodesed knee converted to a total knee replacement were evaluated. Thirty-seven knees (35 patients, 28 female and 7 male) without any motion in the knee were retrospectively reviewed in a multicenter study after total knee arthroplasty. The mean age was 53 years, and the average length of followup was 90 months. The results at followup showed an average 7 degrees lack of extension and 62 degrees flexion. Complications included 24% short term complications and 35% major complications with a 14% infection rate. The total complication rate was 57%. A satisfactory outcome (no pain and an unlimited ambulation distance) was obtained in only 10 patients (29%). Patients with a satisfactory outcome had an average age of 45, and postoperative knee flexion of 87 degrees, significantly different from those with an unsatisfactory outcome. There was no relationship between results and the angle at which the knee was ankylosed preoperatively. This analysis indicates that although success in reconstructing a previously ankylosed or arthrodesed knee is possible, the lack of consistent adequate motion and the complication rate may suggest that the surgeon reconsider the risks and benefits of this difficult procedure.

Adult↗
PubMed1996

The effect of superior placement of the acetabular component on the rate of loosening after total hip arthroplasty.

A method for measurement of the true acetabular region and the approximate femoral head center as well as a classification consisting of four zones for assessment of the acetabular position of the acetabular cup were used to analyze the results of primary total hip arthroplasty with cement in 117 patients (145 hips). All patients had Crowe type-II congenital dysplasia of the hip. The mean age at the time of the arthroplasty was fifty-one years (range, fifteen to seventy-six years), and the mean duration of follow-up was fourteen years (range, two to twenty-two years). The initial position of the acetabular cup outside of the true acetabular region and outside of zone 1 (inferior and medial) was associated with an increase in the rates of loosening (p < 0.05) and revision (p < 0.04) of the femoral components. Cups that initially were more than fifteen millimeters superior to the approximate femoral head center, without lateral displacement, were associated with an increased rate of loosening (p < 0.001) and of revision (p < 0.04) of the femoral components as well as with an increased rate of loosening (p < 0.002) and of revision (p < 0.01) of the acetabular components. These findings suggest that superior positioning of the acetabular component, even without lateral displacement, leads to increased rates of loosening of the femoral and acetabular components. An attempt should be made to position the acetabular component in or near the true acetabular region.

Acetabulum↗
PubMed1996

Clinical outcomes and radiological instability following decompressive lumbar laminectomy for degenerative spinal stenosis: a comparison of patients undergoing concomitant arthrodesis versus decompression alone.

One hundred twenty-four patients with degenerative lumbar stenosis underwent decompression with fusion (32 patients) and without fusion (92 patients) during a 30-month period between 1986 and 1988. Patient-reported satisfaction at a mean follow-up period of 5.8 years (range 4.6-6.8 years) revealed a 79% good or fair outcome and a 21% poor outcome (26 patients). Seven patients (6%) developed lumbar instability, three patients (2%) developed new stenosis at an adjacent unoperated level, and three patients (2%) developed a new disc herniation between 2 and 5 years after surgery. Progressive postoperative spondylolisthesis occurred in 31% of patients with normal preoperative alignment (mean 7.8 mm, range 2-20 mm) and in 73% of patients with preoperative subluxation (mean 5.1 mm, range 2-13 mm) in whom fusion was not attained. Radiological progression did not correlate well with patient-reported outcome. The major conclusions from this study are the following: 1) the majority of patients respond well to this surgery, but complication (22%) and late deterioration (10%) rates are not insignificant; 2) radiological instability is common after decompression for degenerative lumbar spinal stenosis, but this correlates poorly with clinical outcome; 3) there are no definitive clinical or radiological factors that preoperatively predict patients at risk for a poor outcome; 4) post-operative radiological instability is more likely to occur when the following criteria are present: preoperative spondy-degenerated L-4 or a markedly degenerated L-3 disc; and when a radical and extensive decompression greater than one level is planned; and 5) the group at greatest risk for a poor outcome consists of those patients with normal preoperative alignment who do not suffer slippage following surgery.

Adult↗
PubMed1995

Patient outcome with reinfection following reimplantation for the infected total knee arthroplasty.

From 1976 to 1992, 24 knees (24 patients) were treated for reinfection after reimplantation of a prosthesis to treat an infected total knee arthroplasty. Including the index total knee arthroplasty, the average number of total procedures for the affected knee was 9.3 procedures (range, 5-23 procedures), and surgical procedures used for the affected knee after reinfection averaged 3.7 procedures (range, 1-12 procedures). The final outcome included 10 knees with a successful knee arthrodeses, 5 patients with infected prostheses who were prescribed suppressive oral antibiotic treatment, 4 above the knee amputations, 3 persistent pseudarthroses of the knee joint, 1 resection arthroplasty, and 1 uninfected total knee prosthesis. A poor prognosis was associated with use of a hinged knee design: 3 of the 4 amputations were done after a hinge knee prosthesis was implanted; 2 patients had a persistent pseudarthrosis after a failed attempt at knee arthrodesis; 1 patient had a resection arthroplasty; and 1 patient had a retained infected prosthesis. A successful arthrodesis in which the initial attempt included use of an external fixation devices was more likely for prostheses without stems (75%) when compared with cemented stemmed prostheses (40%). Long intramedullary arthrodesis was successful in all 3 attempts. Aspiration for diagnosis followed by oral antibiotic suppression was universally unsuccessful in 4 patients, whereas early aggressive open debridement facilitated retention of the prosthesis in 4 of 6 patients. The increased difficulty in achieving a healed wound, a successful knee arthrodesis, and eradication of infection with subsequent nonprosthetic salvage procedures as well as the attendant morbidity associated with reinfection must be considered carefully and discussed with the patient before the reimplantation prosthesis is inserted to treat the infected total knee arthroplasty.

Adult↗
PubMed1994

The use of porous prostheses in delayed reconstruction of total hip replacements that have failed because of infection.

Between March 1984 and March 1989, thirty-four patients who had an infection at the site of a cemented total hip prosthesis were managed with resection arthroplasty and delayed implantation of a porous total hip prosthesis without cement. The interval from the time of the resection arthroplasty to the implantation of another prosthesis averaged eight months (range, three to nineteen months). At an average of forty-seven months (range, twenty-four to seventy-two months) after the reimplantation, six patients (18 per cent) had recurrence of the infection. Patients who had rheumatoid arthritis were at significantly higher risk for the development of a recurrent infection (p < 0.01). Of the twenty-eight patients who did not have a recurrent infection, six had definite radiographic evidence of loosening of the femoral component at the latest follow-up evaluation. For twenty-five of the twenty-eight patients, sufficient data were available for calculation of the Mayo Clinic hip score; only fourteen (56 per cent) of these patients had a satisfactory functional outcome. The high (68 per cent) rate of complications and the long-term durability of the prosthesis in these patients remain a concern. The fact that 18 per cent of the patients had a recurrent infection suggests that avoidance of the use of bone cement does not improve the rate of resolution of infection after a delayed revision operation in patients who have an infection following a total hip arthroplasty.

Adult↗
PubMed1994

Prevention of deep wound infection after total hip arthroplasty: the role of prophylactic antibiotics and clean air technology.

The role of antimicrobial prophylaxis has been established to be the single most significant factor in the prevention of deep wound infection following total hip arthroplasty. The proper dose, duration of treatment, and type of antibiotic have not been definitively established. The effect of clean air technology techniques has not been universally proven in the clinical setting to provide a reduction in the incidence of infection following total hip arthroplasty. The role of these two methods to prevent deep infection following total hip arthroplasty requires further study.

Antibiotic Prophylaxis↗
PubMed1994

Cemented long-stem revision total knee arthroplasty.

Theoretical concerns about the use of cemented long-stemmed revision total knee arthroplasty include inducing stress shielding with adverse effects on prosthesis fixation. This study details the clinical outcome of 35 patients with 40 cemented long-stemmed kinematic stabilizer revision total knee arthroplasties at followup evaluation averaging 58.2 months (range, 24-111 months). Of these 40 revision arthroplasties, there were 25 long-stemmed tibial components and 38 long-stemmed femoral components. The Knee Society pain score improved from a preoperative value of 38 points (range, 4-80 points) to 83 points (range, 33-100 points) at last evaluation. The Knee Society function score improved from a preoperative value of 46 points (range, 5-100 points) to 64 points (range, 0-100 points) at last evaluation. Initial postoperative radiographs showed tibial bone-cement radiolucencies in 5 knees, but at final followup none of these radiolucencies had progressed. Radiolucencies developed in 5 additional tibial components by the time of final followup, but these were all incomplete and < 1 mm in width. Two femoral components had initial postoperative radiolucencies. These radiolucencies remained stable in 1 knee, whereas the other knee had asymptomatic radiographic loosening. Incomplete radiolucencies of < 1 mm developed in 3 additional femoral components at final followup. The incidence of tibial radiolucencies of 32% in the present study is similar to the incidence of radiolucencies with a nonstemmed revision cemented total knee arthroplasty, with the same prosthetic design, previously reported from the authors' institution.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Treatment of the infected total knee arthroplasty with insertion of another prosthesis. The effect of antibiotic-impregnated bone cement.

Eighty-six patients with 89 infected total knee arthroplasties were treated with insertion of another prosthesis. Treatment was not according to an established protocol for parameters, such as delay between removal of the infected prosthesis and insertion of the new prosthesis, duration of antibiotics, use of antibiotic-impregnated cement spacers or beads, and use of antibiotic-impregnated cement for prosthetic fixation at revision surgery. Final followup averaged 52 months (range, 6-126 months). Complications occurred in 30 (33.7%) knees, with recurrent deep infection developing in 10 (11.24%) knees. Patient age, medical diagnosis, type of microorganism, duration of parenteral antibiotics, delay between the resection and revision surgery, and use of antibiotic-impregnated cement spacers or beads were not correlated with the cure rate of infection. Use of antibiotic-impregnated bone cement for prosthesis fixation at revision surgery was the only variable that correlated with the cure rate of deep infection. Seven (28%) of the 25 knees without antibiotic-impregnated cement for prosthesis fixation developed recurrent infection compared with 3 (4.7%) of 64 knees with antibiotic-impregnated cement for prosthesis fixation. This difference was statistically significant (p = 0.0025, log-rank test).

Adult↗
PubMed1993

V-Y quadricepsplasty in total knee arthroplasty.

The results in 14 consecutive patients (16 knees) who have had total knee arthroplasty (TKA) with a V-Y quadricepsplasty were reviewed. There were eight men and six women with an average age of 66.2 years. Nine patients (ten knees) had revision arthroplasty and five patients (six knees) had primary arthroplasty. Nine of the 14 patients were examined and evaluated in the biomechanics laboratory using the modified Cybex-II system at a mean of three years from surgery. Using the knee rating score of the Hospital for Special Surgery, there were two excellent, ten good, two fair, and two poor results. The average active range of motion was 4 degrees to 85 degrees. Biomechanical testing revealed statistically significant weakness in extension compared with the contralateral side only at test speeds of 120, 180, and 240 degrees per second in those patients who had contralateral normal knees. The affected side at other test speeds were weaker but did not reach statistically significant weakness when compared with the contralateral knee. Comparing V-Y quadricepsplasty to normal medial parapatellar TKA patients, the extensor mechanism was weaker in the V-Y group but not to a significant degree. If one requires a V-Y quadricepsplasty during TKA, one can expect near normal active extension and moderate weakness in extension. Knee scores reflect the difficult reconstructive challenges that are inherent in patients who require a V-Y quadricepsplasty.

Activities of Daily Living↗
PubMed1991

Primary total knee arthroplasty in patients with psoriasis.

Between 1976 and 1988, 50 primary total knee arthroplasties were performed on 34 patients with psoriasis vulgaris. The skin lesions were graded for severity in all patients and the extent of affected body surface was mapped. All patients received peri-operative antibiotics. Only one deep infection, with Staphylococcus aureus, occurred 25 months after operation. The average length of follow-up was nearly four and a half years, being to a minimum of two years or until failure of the arthroplasty. There appears to be no increased risk of deep infection in patient with psoriasis vulgaris undergoing primary total knee arthroplasty.

Adult↗
PubMed1989

Deep postoperative wound infection after carpal tunnel release.

Between January 1976 and December 1985, 3620 carpal tunnel releases were done at the Mayo Clinic. A deep postoperative infection developed in 17 (0.47%) patients. These 17 were compared control group of 102 patients to identify possible risk factors. Statistically significant risk factors included intraoperative instillation of steroid solution into the carpal canal, flexor tendon synovectomy, prolonged operative time, and use of a surgical drain. Infection incidence was 0.87% in males and 0.25% in females (statistically significant). Seven (41%) of the 17 patients had a suboptimal result at final follow-up.

Adult↗
PubMed1988

A comparison of primary and revision total knee arthroplasty using the kinematic stabilizer prosthesis.

The first 121 arthroplasties (in 105 patients) in which the cemented kinematic-stabilizer total knee prosthesis was used for primary arthroplasty or surgical revision at the Mayo Clinic were reviewed. Sixty-six patients (seventy-nine arthroplasties) were followed for a mean of thirty-seven months. There were fifty-three revision and twenty-six primary arthroplasties. The average range of motion in both groups increased from 95 to 101 degrees. Although none of these patients could ascend stairs without support before the operation, thirty-two (51 per cent) could do so at the time of the final follow-up. The incidence of moderate or severe pain was reduced from 86 to 6 per cent. Moderate or severe ligamentous instability had been present in thirty-three knees (42 per cent) preoperatively, but only five knees had significant medial, lateral, anterior, or posterior instability at final follow-up. The Hospital for Special Surgery knee score increased from an average of 56 points to 83 points in all of the knees. At follow-up, the patients who had had primary arthroplasty had 92 per cent good or excellent results and the patients who had had surgical revision had 81 per cent good or excellent results (p less than 0.05). There was no significant difference in the results between the patients who had osteoarthritis and those who had rheumatoid arthritis. Over-all, 85 per cent of the results were good or excellent at final follow-up. Tibial radiolucent lines of one to two millimeters were observed in 29 per cent of the knees at follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗