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PubMed2005

Do older adults with knee osteoarthritis place greater loads on the knee during gait? A preliminary study.

OBJECTIVE: To compare the gait of older adults with knee osteoarthritis (OA) to an age-, sex-, and weight-matched healthy cohort that would provide preliminary data to examine the hypothesis that adults with knee OA have abnormal knee joint moments and place greater loads on the knee joint during walking compared with healthy adults. DESIGN: Nonrandomized, descriptive study of healthy and osteoarthritic older adults. SETTING: University clinical research laboratory. PARTICIPANTS: Ten older adults with tibiofemoral and/or patellofemoral radiographic evidence and pain and disability attributed to knee OA and 10 age-, sex-, and weight-matched healthy adults. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Three-dimensional gait analysis to calculate knee joint forces and hip, knee, and ankle joint moments; an analysis of covariance adjusted for differences in walking speed between the groups; electromyographic data to verify our interpretation of the knee joint moment data. RESULTS: The joint forces and moments did not differ statistically between the OA and healthy groups. Nonsignificant differences in the OA group relative to the healthy group included between 7% and 8% greater knee joint compressive (OA group, 3.67+/-0.24 body weight [BW]; healthy group, 3.40+/-0.24 BW) and shear (OA group, 0.47+/-0.04 BW; healthy group, .44+/-.04 BW) forces, 33% higher knee extension moments (OA group, .32+/-.07 Nm/kg; healthy group, .24+/-.07 Nm/kg), and 24% lower knee internal abduction moments (OA group, .25+/-.06 Nm/kg; healthy group, .33+/-.06 Nm/kg). CONCLUSIONS: Previous research suggests that mechanical overload may be associated with knee OA. Our results do not provide statistical evidence to support this hypothesis. Nevertheless, the trends in the data, along with previous results, suggest the need to investigate further the possible existence of a biomechanical pathway to knee OA.

Aged↗

PubMed2005

Associations among knee adduction moment, frontal plane ground reaction force, and lever arm during walking in patients with knee osteoarthritis.

The adduction moment about the knee during walking gait has been proposed as an indirect measure of dynamic knee joint load. However, the relative contributions of the variables primarily used to calculate the knee adduction moment have not been investigated. The objectives of this paper were to: (1) describe and compare the magnitude and temporal characteristics of the knee adduction moment, frontal plane lever arm, and frontal plane ground reaction force (GRF) during gait in patients with knee osteoarthritis (OA) and, (2) examine the associations among these variables. Results indicated that both the knee adduction moment and the frontal plane GRF varied considerably throughout stance and exhibited the characteristic "double-hump" pattern, while the frontal plane lever arm magnitude varied only slightly during stance. Knees with OA had significantly greater peak knee adduction moments and frontal plane lever arms, but significantly less peak frontal plane GRF than knees without OA. Pearson product moment correlations indicated a higher association between peak knee adduction moment and peak frontal plane lever arm than between peak knee adduction moment and peak frontal plane GRF, particularly in knees with OA. These results suggest that the frontal plane lever arm assessed during walking is an important variable in the examination of knee OA, and warrants further investigation.

Adult↗

PubMed1979

Foot-pounds of torque of the normal knee and the rehabilitated postmeniscectomy knee.

Foot-pounds of torque of the knee flexors and knee extensors of eight rehabilitated patients who had had meniscectomies were obtained isometrically and at 60 and 210 degrees per second by use of an isokinetic apparatus. Our purpose was to test the null hypothesis that no significant difference in torque would be manifested between the rehabilitated postmeniscectomy knee and the normal knee. Mean torque developed by the rehabilitated postoperative knee was 10 to 12 percent less than the mean torque developed by the normal knee. We found a significant difference between means of torque of the normal knee and the rehabilitated knee for isometric flexion, rapid dynamic flexion, and rapid dynamic extension. Means of torque of knee extension for the three types of contraction for both knees of the subjects demonstrated similar patterns in which torque developed isometrically was greater than torque developed by slow dynamic tension, which in turn was greater than torque developed by rapid dynamic contraction. Means of torque of knee flexion for the three types of contraction for both knees of the subjects created patterns in which torque developed isometrically was essentially equal to torque developed by slow dynamic tension, and both these measurements exceeded torque developed by rapid dynamic contractions. Overall, the results suggest that physical therapists need to use rehabilitative techniques that promote muscular power and muscular endurance in addition to muscular strength and that more attention needs to be directed to the rehabilitation of knee flexors.

Adolescent↗

PubMed2001

Component rotation and anterior knee pain after total knee arthroplasty.

All patients undergoing cruciate-retaining primary total knee arthroplasty for degenerative osteoarthritis at one center were studied prospectively. Clinical and radiographic followup was obtained at a minimum 5 years in 102 knees in 73 patients. Patients were asked specifically about the presence of the pain in the anterior aspect of the knee in the vicinity of the patella and rated the severity of the pain on a visual analog scale. Significant anterior knee pain rating at least 3 of 10 on the visual analog scale was present in 16 knees (13 patients). Eleven patients with 14 symptomatic knees agreed to undergo computed tomography scanning to accurately determine the rotation of the tibial and femoral components. The epicondylar axis and tibial tubercle were used as references using a previously validated technique. A control group of 11 asymptomatic patients (14 knees), matched for age, gender, and length of followup also underwent computed tomography scanning. All patients in both groups had normal axial alignment. There was a highly significant difference in tibial component rotation between the two groups with the patients with anterior knee pain averaging 6.2 degrees internal rotation compared with 0.4 degrees external rotation in the control group. There also was a significant difference in combined component rotation with the patients with anterior knee pain averaging 4.7 degrees internal rotation compared with 2.6 degrees external rotation in the control group. There was no significant difference in the degree of radiographic patellar tilt or patellar subluxation between the two groups. Patients with combined component internal rotation were more than five times as likely to experience anterior knee pain after total knee arthroplasty compared with those with combined component external rotation. Component malrotation is a significant factor in the development of anterior knee pain after total knee arthroplasty.

Aged↗

PubMed2005

Knee proprioception in patients with osteosarcoma around the knee after modular endoprosthetic reconstruction.

BACKGROUND: Proprioception as an outcome for patients with osteosarcoma who have undergone modular endoprosthetic knee reconstruction has not been studied, as far as we know. The primary purpose of the present study was to understand the differences in knee proprioception between this patient population and control subjects. We also compared differences in proprioception between patients with tumors at different sites and between patients who had different proportions of bone length excised. METHODS: We evaluated twenty patients who had undergone a wide resection of a tumor about the knee followed by reconstruction with a modular endoprosthesis. The mean age of the patients was 21.7 years. The patients were grouped according to tumor site, i.e., the distal part of the femur or the proximal part of the tibia; they were also grouped according to the length of resected bone (<40% or >or=40% of the length of the bone). Another twenty age-matched control subjects were recruited for this study. Knee proprioception was evaluated by comparing active and passive angular repositioning of the involved limb and the normal limb in the patients and the dominant limb in the central subjects. RESULTS: The absolute matching error of active and passive repositioning was 2.7 degrees +/- 2.1 degrees and 2.9 degrees +/- 2.2 degrees , respectively, for knees treated operatively and 3.2 degrees +/- 2.1 degrees and 2.1 degrees +/- 1.3 degrees , respectively, for the dominant knees in the control subjects. The differences between the operatively treated knees and the control knees were not significant (p > 0.05). There was also no significant difference in proprioception between the patients with a distal femoral tumor and those with a proximal tibial tumor (p > 0.05). The proprioception of the patients with a greater length of bone resected was significantly worse in both lower extremities than that of patients with a shorter resected length (p = 0.016 for the normal side and p = 0.025 for the involved side). CONCLUSIONS: The proprioception of the involved knees in the patients with osteosarcoma who had modular endoprosthetic reconstruction was not found to be different from the normal knees or the knees in the control subjects. On the basis of our data, we found that proprioception is probably not influenced by the tumor site. Conversely, resection length appears to be an important factor. These study findings may be used as a reference for knee proprioception in patients with osteosarcoma who have a modular endoprosthetic knee reconstruction.

Adolescent↗

PubMed2005

Total knee replacement for posttraumatic degenerative arthritis of the knee.

OBJECTIVE: To evaluate the results of total knee arthroplasty (TKA) in patients with posttraumatic degenerative arthritis due to a previous fracture around the knee. METHODS: We analyzed the results of 15 TKAs, performed from 1997 to 2003, in 15 patients with post-traumatic degenerative arthritis due to a previous fracture around knee. There were 3 women and 12 men with an average age of 58 years (range, 31-76 years). The time from fracture to arthroplasty averaged 8.2 years (range, 2-27 years). Internal fixation had previously been performed in 8 patients resulting in retained hardware. At the time of arthroplasty a femoral fracture malunion was present in two knees. Lateral retinacular release (4 knees), extensor mechanism realignment (1 knee) or medial collateral ligament reconstruction (1 knee) were needed at the time of arthroplasty. RESULTS: Follow-up averaged 35 months (range, 12-73 months). No patient was lost for follow-up. According to the Knee Society Score scale, the mean preoperative knee score was 37 (range, 10-70) and functional score was 41 (range, 0-60). They were improved significantly to a mean of 84 (range, 10-100) and 76 (range, 20-100) points, respectively at the latest follow-up. The mean knee arc of motion were improved from 84 degree preoperation to 94 degree at the latest follow-up. Postoperative manipulation under anesthesia for poor motion was carried out in 4 knees. No knee had aseptic loosening that required subsequent revision. Two knees developed superficial infection and were treated with debridement. It subsequently recovered with the retention of components. CONCLUSIONS: Significant improvement in function and relief of pain has been achieved in patients with previous fractures undergoing subsequent TKA. However, this procedure is technically demanding and patients are at increased risk for restricted motion and need more care following TKA. This study suggests that the outcome of TKA may be improved further by making special efforts to restore limb alignment, to ensure correct component positioning, and to manage soft tissue balance.

Adult↗

PubMed1994

Tricompartmental knee replacement. A comparison of orthopaedic surgeons' self reported performance rates with surgical indications, contraindications, and expected outcomes. Knee Replacement Patient Outcomes Research Team.

The chance of a person with osteoarthritis of the knee receiving a knee replacement is highly variable. To understand better the reasons for this variation, all practicing orthopaedists in Indiana were surveyed about their management of severe knee osteoarthritis and their perception of tricompartmental knee replacement as a therapeutic option. Their perceptions of indications and outcomes of knee replacement were compared with the self reported annual number of patients for whom they performed (or referred to other surgeons for) tricompartmental knee replacements. A completed survey was returned by 220 (79%) of the 280 orthopaedists surveyed; analyses were limited to the 188 respondents who had cared for at least one patient with osteoarthritis of the knee in the prior 2 weeks (mean = 13). These surgeons reported performing (or referring patients for) a mean of 31 knee replacements in the prior year (SD 45, median 21, range 0-480 knee replacements). There was strong agreement (> 95%) among respondents for seven (21%) of 33 surgical indications and contraindications, and more general agreement (> 60%) for 21 (64%). In the five factors (15%) for which there was disagreement, there was no consistent relationship between opinions and self reported knee replacement performance rate. Surgeons reporting more knee replacements had significantly higher estimates of pain relief and functional improvement following surgery, and lower estimates of prosthesis infection and failure rates. When all responses were considered together, four decision factors correlated independently with the performance of more knee replacements, but these four factors explained only 24% of the variation in self reported knee replacement performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2006

Mobile vs. fixed bearing unicondylar knee arthroplasty: A randomized study on short term clinical outcomes and knee kinematics.

The literature contains limited yet controversial information regarding whether a fixed or a mobile bearing implant should be used in unicompartmental knee arthroplasty (UKA). This randomized study was to further document the performance and comparison of the two designs. Fifty-six knees in 48 patients (mean age of 72 years) undergoing medial UKA were randomized into a fixed bearing (Miller/Galante) or a mobile bearing (Oxford) UKA. The 2 year clinical outcomes (clinical scores), radiographic findings, and weight bearing knee kinematics (assessed using RSA) were compared between the two groups. The mobile bearing knees displayed a larger and an incrementally increased tibial internal rotation (4.3 degrees, 7.6 degrees, 9.5 degrees vs. 3.0 degrees, 3.0 degrees, 4.2 degrees respectively at 30 degrees, 60 degrees, 90 degrees of knee flexion) compared to the fixed ones. The medial femoral condyle in the mobile bearing knees remained 2 mm from the initial position vs. a 4.2 mm anterior translation in the fixed bearing knees during knee flexion. The contact point in the mobile bearing implant moved 2 mm posteriorly vs. a 6 mm anterior movement in the other group. The mobile bearing knees had a lower incidence of radiolucency at the bone implant interface (8% vs. 37%, p < 0.05). The incidence of lateral compartment OA and progression of OA at patello-femoral joint were equal. No differences were found regarding Knee Society Scores, WOMAC, and SF-36 scores (p > 0.05). This study indicates that mobile bearing knees had a better kinematics, a lower incidence of radiolucency but not yet a better knee function at 2 years.

Aged↗

PubMed1996

Self-reported functional status in osteoarthritis of the knee in a rural southern community: the role of sociodemographic factors, obesity, and knee pain.

OBJECTIVE: This study examined the roles of sociodemographic factors (age, race, gender, education, marital status), obesity, and severity of radiographic knee osteoarthritis (OA) and knee pain on self-reported functional status. METHODS: The sample included 1,272 African-American and Caucasian individuals, aged 45 years or older, from the Johnston County Osteoarthritis Project. Analysis of variance was used to assess variation in mean Health Assessment Questionnaire (HAQ) scores by the above variables. RESULTS: Mean HAQ scores differed by severity of radiographic knee OA and knee pain, obesity, and all demographic factors (P < 0.0001), except race. Only age, female sex, obesity, and knee pain severity were independent effects (P < 0.0009). Disability associated with knee pain varied by both radiographic knee OA severity and obesity. CONCLUSIONS: Knee pain severity was more important than radiographic knee OA severity in determining disability. Obesity was independently associated with disability and compounded disability from knee pain. Studies of disability in knee OA should include assessment of obesity, severity of radiographic knee OA, and severity of knee pain, as well as their interactions.

Activities of Daily Living↗

PubMed1995

Association of radiographic features of osteoarthritis of the knee with knee pain: data from the Baltimore Longitudinal Study of Aging.

OBJECTIVE: To examine the association between self-reported knee pain and radiographic features of osteoarthritis (OA) of the knee. METHODS: A sample of participants in the Baltimore Longitudinal Study of Aging (452 Caucasian males and 223 Caucasian females) completed questionnaires and underwent a standing radiograph of both knees at the same biennial visit between 1984 and 1989. Radiographs were interpreted using both the Kellgren-Lawrence and individual features scales. Odds ratios were calculated for the association of radiographic features with knee pain after adjustment for age, sex, and body mass index. RESULTS: Overall, 156 (23%) persons reported ever having knee pain, and 104 (15%) reported current knee pain (within the previous year). Both ever knee pain and current knee pain were significantly associated with the presence of definite knee OA (Kellgren-Lawrence grade > or = 2) and with the presence of all individual features. There was a direct relationship between all measures of severity of radiographic OA and knee pain. CONCLUSION: These data demonstrate that radiographic features of knee OA are significantly associated with knee pain. The data also support the continued use of the Kellgren-Lawrence grading scale for defining knee OA in population studies.

Adult↗

PubMed2004

Knee adduction moment and development of chronic knee pain in elders.

OBJECTIVE: To determine whether the adduction moment at the knee during locomotor activity contributes to the development of future chronic knee pain. METHODS: We studied 132 community-dwelling elders who had undergone a full kinetic and kinematic motion analysis while performing 4 different activities: standing, walking, rising from a chair, and descending stairs. We contacted the participants 3-4 years after their baseline locomotion analysis and identified those who reported no knee pain at the time of motion analysis but who subsequently developed new chronic knee pain at followup. We examined whether the development of new chronic knee pain was associated with higher peak adduction moment at the knee during activities, measured at baseline. RESULTS: Of the 132 elders evaluated in 1995-1996, 118 (89%) were contacted in 1999. Of the 118 contacted, 80 (mean age 75 years; 78% women) had no lower extremity prosthetic joints at baseline, no known underlying inflammatory arthritis at baseline nor followup, and no baseline knee pain. At followup, 7 had developed new chronic knee pain defined as pain or stiffness on most days of the month and with walking 2 blocks or using stairs. Compared with those who did not develop knee pain, those who did develop new chronic knee pain had higher baseline adduction moments for all activities (P = 0.01), ranging from 8% higher during chair rise to 39% higher during stair descent. CONCLUSION: We found that greater adduction moment at the knee during activities contributes to the development of future chronic knee pain. Our results suggest that biomechanical factors may play an important role in the pathogenesis of knee pain and should be studied further.

Aged↗

PubMed2006

Knee pain, knee osteoarthritis, and the risk of fracture.

OBJECTIVE: Patients with osteoarthritis (OA) have increased bone mineral density; however, the association between knee OA and fracture is controversial. Few data exist on the association between knee pain and fracture. We examined the association of knee OA and knee pain with fracture and falls in elderly men and women. METHODS: The study group comprised 6,641 men and women ages > or =75 years who participated in a 3-year randomized controlled trial of intramuscular vitamin D therapy. Patients completed a questionnaire about knee pain and OA. Fracture and fall data were collected prospectively every 6 months. RESULTS: Knee pain prevalence and a clinician diagnosis of knee OA were 35.2% and 6.8%, respectively. A total of 436 incident nonvertebral fractures were reported, and 3,992 patients sustained a fall. Prevalent knee pain was associated with an increased risk of falls (hazard ratio [HR] 1.26, 95% confidence interval [95% CI] 1.17-1.36) and hip fracture (HR 2.0, 95% CI 1.18-3.37). Increasing severity of knee pain was associated with a greater risk of falls and hip fracture. Clinician diagnosis of knee OA was associated with an increased risk of nonvertebral fractures (HR 1.61, 95% CI 1.09-2.36). The increased risk of fracture was not substantially reduced by adjusting for falls, but was attenuated by adjustment for the use of walking aids. CONCLUSION: Patients with a clinical diagnosis of knee OA and with knee pain have an increased risk of nonvertebral and hip fracture. This is not explained by the increased risk of falls, but is more likely to be due to the severity of falls sustained. Knee pain and OA should be regarded as independent risk factors for fracture.

Aged↗

PubMed2004

Muscles that influence knee flexion velocity in double support: implications for stiff-knee gait.

Adequate knee flexion velocity at toe-off is important for achieving normal swing-phase knee flexion during gait. Consequently, insufficient knee flexion velocity at toe-off can contribute to stiff-knee gait, a movement abnormality in which swing-phase knee flexion is diminished. This work aims to identify the muscles that contribute to knee flexion velocity during double support in normal gait and the muscles that have the most potential to alter this velocity. This objective was achieved by perturbing the forces generated by individual muscles during double support in a forward dynamic simulation of normal gait and observing the effects of the perturbations on peak knee flexion velocity. Iliopsoas and gastrocnemius were identified as the muscles that contribute most to increasing knee flexion velocity during double support. Increased forces in vasti, rectus femoris, and soleus were found to decrease knee flexion velocity. Vasti, rectus femoris, gastrocnemius, and iliopsoas were all found to have large potentials to influence peak knee flexion velocity during double support. The results of this work indicate which muscles likely contribute to the diminished knee flexion velocity at toe-off observed in stiff-knee gait, and identify the treatment strategies that have the most potential to increase this velocity in persons with stiff-knee gait.

Gait↗

PubMed2006

Design and evaluation of a stance-control knee-ankle-foot orthosis knee joint.

Conventional knee-ankle-foot orthoses (KAFOs) are prescribed for people with knee-extensor muscle weakness. However, the orthoses lock the knee in full extension and, therefore, do not permit a natural gait pattern. A new electromechanical stance-control knee-ankle-foot orthosis (SCKAFO) knee joint that employs a novel friction-based belt-clamping mechanism was designed to enable a more natural gait. The SCKAFO knee joint allows free knee motion during swing and other non-weight-bearing activities and inhibits knee flexion while allowing knee extension during weight bearing. A prototype SCKAFO knee joint was mechanically tested to determine the moment at failure, loading behavior, and wear resistance. The mean maximum resisting moment of the SCKAFO knee joint over five loading trials was 69 Nm +/- 4.9 Nm. The SCKAFO knee-joint strength and performance were sufficient to allow testing on a 90 kg subject at normal walking cadence. Proper function of the new electromechanical knee joint was verified in walking trials of an able-bodied subject.

Ankle Joint↗

PubMed1982

[A biomechanical study of osteoarthritis of the knee with special reference to the rotatory movement of the knee joint].

Clinical picture of osteoarthritis of the knee (OA) was investigated from the viewpoint of dynamic rotatory movement of the knee. With regard to 140 normal knee joints and 263 OA joints, dynamic rotatory movement of the knee was measured and analyzed on serial lateral X-ray films of the knee during loading. In normal knee joints, the femur showed internal rotation on the tibia from a 90 degrees flexion to maximal extension. In OA joints, rotatory movement on terminal extension of the knee, i.e., screw home movement, was disturbed in the early stage. With progress of osteoarthritis, the previously mentioned rotatory movement of the knee joint was reduced, and finally adverse rotatory movement appeared. The measured results of the rotatory movement of the knee in normal and every grades of OA joints were analyzed by the least squares method and subsequently depicted in an approximate curve of the fifth degree. Consequently, osteoarthritis of the knee was graded into 4 groups, on the basis of rotatory movement of the knee. Thus, it is concluded that disturbed rotatory movement of the knee may be a key factor in the progress of osteoarthritis of the knee.

Adolescent↗

PubMed2003

Conversion of a fused knee with use of a posterior stabilized total knee prosthesis.

BACKGROUND: Typically a hinged or condylar constrained prosthesis is recommended for total knee arthroplasty in a fused knee, to substitute for the absent or deficient collateral ligaments. The purpose of this study was to evaluate the stability and clinical results after the use of a posterior stabilized prosthesis in the conversion of a fused knee to a total knee arthroplasty. METHODS: Thirty-six patients (thirty-six knees) with a mean age of 39.2 years underwent conversion of a fused knee to a total knee arthroplasty with a posterior stabilized prosthesis. The mean duration of ankylosis had been 24.5 years. Clinical and radiographic evaluation was carried out preoperatively; at six weeks and three, six, and twelve months postoperatively; and annually thereafter. The mean duration of follow-up was 7.7 years. RESULTS: The mean preoperative Hospital for Special Surgery knee score of 60 points improved to 83.2 points at the final follow-up examination. Twenty-two knees were pain-free, and the remaining fourteen were mildly painful after prolonged walking. The mean amount of active flexion in the entire group was 77.7 degrees. The extension lag in the entire group averaged 12.5 degrees. Complications included necrosis of the skin edges in eighteen knees (50%), a rupture of the quadriceps tendon in two patients, and a pyogenic infection in two. No prosthesis required revision because of clinical or radiographic loosening. CONCLUSIONS: We believe that when the soft-tissue sleeves in a previously fused knee are carefully preserved intraoperatively, they can provide adequate stability after total knee arthroplasty with a posterior stabilized prosthesis. Therefore, we believe that use of that type of prosthesis is a reasonable alternative to the use of a more constrained implant in the treatment of this condition.

Adult↗

PubMed2005

Can normal knee kinematics be restored with unicompartmental knee replacement?

BACKGROUND: Unicompartmental replacement can be an alternative to tibial osteotomy in younger, active patients with unicompartmental knee disease. In unicompartmental replacement, the other compartments and knee ligaments are largely untouched. Therefore, it was hypothesized that the knee kinematics after unicompartmental replacement may also be unchanged. To test this hypothesis, knee kinematics and quadriceps tension were recorded before and after replacement with a unicompartmental design and then with a tricompartmental design. METHODS: Six human cadaver knees were tested before implantation, after implantation with a bicruciate-retaining unicompartmental knee prosthesis, and after implantation with a posterior cruciate-retaining tricompartmental knee prosthesis. The unicompartmental prosthesis was initially implanted, and it was then revised to a total condylar knee replacement. The knee kinematics were measured with use of an electromagnetic tracking device while the knee was put through dynamic simulated stair-climbing under peak flexion moments of approximately 40 N-m. Quadriceps tension was also measured for all three conditions. RESULTS: No significant differences in tibial axial rotation were noted between the intact and unicompartmental conditions. However, tricompartmental replacement significantly affected tibial axial rotation (p = 0.001). Femoral rollback was not significantly affected by either unicompartmental or tricompartmental arthroplasty. Quadriceps tension was also similar among all three conditions. CONCLUSIONS: In this in vitro cadaver study, the tricompartmental replacement significantly changed knee kinematics while the unicompartmental replacement preserved normal knee kinematics.

Aged↗

PubMed2001

Knee joint kinematics, fixation and function related to joint area design in total knee arthroplasty.

The aim was to study the influence of different designs of the joint area on tibial component fixation, kinematics and clinical outcome after a cemented total knee arthroplasty (TKA). The HSS score and a special questionnaire were used at the clinical examination. Conventional radiography was done to record the positioning of the implants and development of radiolucencies. The migration and inducible displacement were evaluated using radiostereometry (RSA). The kinematics of the knee during active extension was studied using dynamic RSA. In randomised and prospective studies 87 knees in 83 patients (28 male, 55 female, age 69, range 50-83) received an AMK (DePuy, Johnson & Johnson) TKA. The patients were divided into two groups. In group 1 the patients had varus/valgus deformities of < or = 5 degrees and the PCL was retained. The PCL was resected in group 2 where the patients had deformities exceeding 5 degrees and/or fixed flexion deformities of more than 10 degrees. In group 1 a flat (F, n = 20) or a concave (C, n = 20) design was implanted (study 3). In group 2 (study 4) the patients received a concave (n = 25) or a posterior-stabilised (PS, n = 22) tibial plateau. The migration of the tibial component, positioning of the prosthesis, development of radiolucencies and the clinical outcome was evaluated after 1 and 2 years. Twenty-two patients (11 F, 11 C) in group 1 (study 1) and 22 knees in 20 patients in group 2 (study 2, 11 C, 11 PS) were examined 1 year post-operatively to evaluate the kinematics of the knee. Eleven normals served as controls. During active extension of the knee the inducible displacements of the tibial component were recorded in 16 knees (15 patients). Based on successful RSA examinations 5 knees (4 F, 1 C) from group 1 and 11 knees (5 C, 6 PS) from group 2 were selected (study 5). Abnormal kinematics and especially increased AP translations compared to normals (p < 0.0005) were recorded in all designs. The concave design showed the widest AP-translations in both studies. The clinical outcome in terms of HSS score did not differ between the flat versus the concave designs in study 1 and between the concave versus the PS implants in study 2. Up to two years the migration of the tibial component and the development of radiolucent lines were of the same magnitude for the flat versus the concave inserts in study 3 and the concave versus the PS design in study 4. Also did the positioning of the implant and the fulfillment of the patients expectations on the surgery preoperatively not differ. The AMK prosthesis migrated at about the same amount as have been reported for similar designs. In study 5 all implants showed a correlation between some of the inducible displacements (anterior-posterior tilting and maximum total point motion) and the corresponding migration 0-2 years. The more the anterior tilt the more the migration in the same direction. If the PCL was sacrificed during the knee replacement the change into increased anterior tilt occurred earlier (i.e. at more degree of flexion) if a concave insert was used compared to the PS design. When the active extension reached 25 degrees there were more anterior tilt of the tibial component in the concave design (p = 0.001) and if the tibial plateau centre had a medial position (p < 0.0005). Compared with normal knees all prosthetic designs showed abnormal pattern of motion. The extent of this abnormality was influenced by the design of the joint area. A corresponding influence on the fixation of the tibial component could not be verified. The choice of joint area and recorded kinematics had no or small influence on the clinical results. Feelings of instability could to some extent be related to the kinematics of the knee joint.

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