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PubMed1998

Tibiofemoral contact pressures in degenerative joint disease.

Using tibiofemoral joints from older (age, 53-80 years) human cadavers with articular cartilage degeneration, contact pressures and contact areas were measured in the extended knee in four conditions: (1) neutral alignment; (2) 5 degrees varus (simulating single limb stance of gait); (3) 5 degrees valgus; and (4) after a 5 degrees proximal tibial closing wedge valgus osteotomy. In degenerated cartilage, contact pressures were reduced at the lesion sites and were high on the borders of the lesions. No statistically significant changes occurred in contact pressures and areas when values from neutral loading were compared with values during loading in each of the other three conditions. Lateral average and maximum contact pressures were less in varus loading than in valgus loading. Equal medial and lateral contact pressures during varus loading, in contrast to lower medial than lateral contact pressures in the other three loading, supports the theory that the varus moment imposed on the knee in single limb stance could be a mechanism causing medial tibiofemoral osteoarthritis. The 5 degrees valgus osteotomy resulted in contact pressures similar to those in neutral loading. These experiments do not support the value of the 5 degrees valgus osteotomy in reducing contact pressures on the medial tibial plateau.

Aged↗

PubMed1999

Does laxity alter the relationship between strength and physical function in knee osteoarthritis?

OBJECTIVE: Since strengthening interventions have had a lower-than-expected impact on patient function in studies of knee osteoarthritis (OA) and it is known that laxity influences muscle activity, this study examined whether the relationship between strength and function is weaker in the presence of laxity. METHODS: One hundred sixty-four patients with knee OA were studied. Knee OA was defined by the presence of definite osteophytes, and patients had to have at least a little difficulty with knee-requiring activities. Tests were performed to determine quadriceps and hamstring strength, varus-valgus laxity, functional status (Western Ontario and McMaster Universities Osteoarthritis Index Physical Functioning subscale [WOMAC-PF] and chair-stand performance), body mass index, and pain. High and low laxity groups were defined as above and below the sample median, respectively. RESULTS: Strength and chair-stand rates correlated (r = 0.44 to 0.52), as did strength and the WOMAC-PF score (r = -0.21 to -0.36). In multivariate analyses, greater laxity was consistently associated with a weaker relationship between strength (quadriceps or hamstring) and physical functioning (chair-stand rate or WOMAC-PF score). CONCLUSION: Varus-valgus laxity is associated with a decrease in the magnitude of the relationship between strength and physical function in knee OA. In studies examining the functional and structural consequences of resistance exercise in knee OA, stratification of analyses by varus-valgus laxity should be considered. The effect of strengthening interventions in knee OA may be enhanced by consideration of the status of the passive restraint system.

Adult↗

PubMed2000

A biomechanical analysis of a medial unloading brace for osteoarthritis in the knee.

OBJECTIVES: The goals of the study were to measure the force applied to the lateral side of the knee by a valgus loading brace designed for patients with medial compartment osteoarthritis (OA) and to compare the varus moment at the knee during level gait with and without the brace. METHODS: Five subjects diagnosed with medial compartment OA were fitted with a custom Monarch valgus loading knee brace. A 3-dimensional videobased motion analysis system and force plate information were used to calculate forces and moments at the knee. An instrumented condylar bladder was used to determine the force applied to the knee by the brace. The varus moments for the braced and unbraced trials were compared during gait at 15%, 20%, 25%, and 30% of stance. RESULTS: The Monarch brace significantly reduced the varus moment at 20% and 25% of stance. The valgus force measured with the custom condylar bladder remained fairly constant throughout the first 80% of the stance phase. CONCLUSIONS: The reduced various moment observed for the braced condition demonstrates the biomechanical function of the brace in 5 subjects and may contribute to a reduction of pain for patients with medial compartment OA.

Activities of Daily Living↗

PubMed1995

Laxity characteristics of normal and pathological murine knee joints in vitro.

The aim of this study was to validate a device developed previously to measure laxity of murine knee joints and to investigate whether experimentally induced pathological conditions result in measurable laxity. The laxity characteristics of normal murine knee joints were derived from measurements of 25 left knees of normal mice. Reproducible, nonlinear s-shaped load-displacement curves were determined, and parameters of anterior-posterior translation, varus-valgus rotation, and compliance were calculated from the curves. No differences were found between the left and right knee joints of eight mice. The average displacement between 0.8 N of anterior force and 0.8 N of posterior force was 0.47 +/- 0.10 mm. The endpoint compliances for anterior and posterior displacements were 0.16 +/- 0.03 and 0.16 +/- 0.04 mm/N, respectively. The average rotation between a 4 Nmm valgus moment and a 4 Nmm varus moment was 17.4 +/- 3.3 degrees. The endpoint compliances for varus and valgus rotations were 1.1 +/- 0.7 and 1.0 +/- 0.3 degrees/Nmm, respectively. Storage of the joints at -70 degrees C had no effect on laxity. We also studied the parameters of laxity after pathology of the knee joint was induced. Zymosan-induced or antigen-induced arthritis did not increase laxity of the joint. In an osteoarthritis model induced by injection of collagenase, laxity was markedly increased. In conclusion, laxity in the knees of mice can be measured reproducibly and changes in the characteristics of laxity due to pathological conditions can be quantified.

Animals↗

PubMed1995

Combined knee loading states that generate high anterior cruciate ligament forces.

Injuries to the anterior cruciate ligament frequently occur under combined mechanisms of knee loading. This in vitro study was designed to measure levels of ligament force under dual combinations of individual loading states and to determine which combinations generated high force. Resultant force was recorded as the knee was extended passively from 90 degrees of flexion to 5 degrees of hyperextension under constant tibial loadings. The individual loading states were 100 N of anterior tibial force, 10 Nm of varus and valgus moment, and 10 Nm of internal and external tibial torque. Straight anterior tibial force was the most direct loading mechanisms; the mean ligament force was approximately equal to applied anterior tibial force near 30 degrees of flexion and to 150% of applied tibial force at full extension. The addition of internal tibial torque to a knee loaded by anterior tibial force produced dramatic increases of force at full extension and hyperextension. This loading combination produced the highest ligament forces recorded in the study and is the most dangerous in terms of potential injury to the ligament. In direct contrast, the addition of external tibial torque to a knee loaded by anterior tibial force decreased the force dramatically for flexed positions of the knee; at close to 90 degrees of flexion, the anterior cruciate ligament became completely unloaded. The addition of varus moment to a knee loaded by anterior tibial force increased the force in extension and hyperextension, whereas the addition of valgus moment increased the force at flexed positions. These states of combined loading also could present an increased risk for injury. Internal tibial torque is an important loading mechanism of the anterior cruciate ligament for an extended knee. The overall risk of injury to the ligament from varus or valgus moment applied in combination with internal tibial torque is similar to the risk from internal tibial torque alone. External tibial torque was a relatively unimportant mechanism for generating anterior cruciate ligament force.

Aged↗

PubMed1986

The static stabilizing function of the popliteal tendon in the knee. An experimental study.

We investigated the importance of the anterior cruciate ligament (ACL), its two components (the AMP and PLP), and the lateral compartment ligaments with special attention to the popliteal tendon (PT) in relation to valgus-varus, axial rotation, and anterior-posterior instability. Mobility patterns were drawn from 15 osteoligamentous knee preparations after successive transection of the structures. Even when combined lesion involved the lateral collateral ligament (LCL), the PT, and the posterolateral capsule (PLC), anterior tibial displacement was not effected until the ACL was cut. The lateral structures acted as secondary restraints to anterior displacement, and prevented simultaneous anterolateral rotation during application of the anterior force. LCL and PLC transection affected varus stability in full extension, and instability improved on additional section of the PT, even if the ACL remained intact. Maximum instability after combined lateral lesion occurred at 40 degrees of flexion, whether the ACL was transected or not. Further flexion caused a rapid decrease of instability. The PT was shown to effectively restrain varus instability from 0 to 90 degrees of flexion. It was experimentally established with regard to axial rotation that marked posterolateral instability was impossible with an intact PT. Maximum instability was recorded at 30 degrees of flexion after combined lesion to the lateral structures. Even in the extension, considerable posterolateral instability was observed. The restraining effect of the PLC was prominent in extension.

Biomechanical Phenomena↗

PubMed1984

Roentgenologic findings of the hydrolethalus syndrome.

The hydrolethalus syndrome is an autosomal recessive malformation syndrome which has been recently described in Finland. The name hydrolethalus refers to the main findings, namely polyhydramnios, hydrocephalus and lethality. The patients are either stillborn or die soon after birth. The typical roentgenologic findings are hypoplasia of the tibia associated with the anomalies of the respective bone ray, e.g. metatarsus primus varus atavisticus, hallux varus or hallux duplex varus and hydrocephalus with extreme micrognathia and a specific midline defect of the occipital bone.

Abnormalities, Multiple↗

PubMed1998

[Fracture of the radial condyle of the humerus in the growth period].

In an overview the clinical and academic problems of this kind of fractures are described and their treatment is discussed. The most important problem is the pseudarthrosis that can happen in the framework of a conservative treatment of displaced fractures, rarely after operative treatment with K-wires. A rather academic problem is the obligatory growth disturbance of a partial stimulation of the lateral part of the growth plate. This leads to radial overgrowth and thus to a more or less distinct varus deformity. The extent of varus deformity is dependent on the time till consolidation, which is longest in conservatively treated fractures and shortest in those treated with compression screw osteosynthesis. An additional academic problem is the so-called fishtail deformity that becomes radiological visible at the end of growth. This deformity has no clinical significance. Pseudarthrosis, varus and fishtail deformity are a result of increasing instability of primarily or secondarily displaced fractures. All three problems can be avoided by metaphyseal compression osteosynthesis with an AO small-fragment screw with an additional axial K wire in the trochlea. Our own long-term results are shown and compared with the results of other procedures in the literature.

Adolescent↗

PubMed2003

[Kinematic analysis before and after bicondylar resurfacing knee arthroplasty].

Knee joint motion appears as a hinge movement around the flexion-extension axis. Corresponding to the rolling-sliding mechanism and alternative models of knee joint kinematics, an instant center pathway must be expected. The current photogrammetric investigation aimed to analyze these pathways when assessed in the sagittal plane in patients with preoperative varus or valgus deformity. A total of 40 patients either with varus or valgus deformity (20 in each group) were examined before and 6 months after implantation of PFC-SIGMA prostheses. Apart from the influence of knee joint deformity, a so-called soft tissue ratio was investigated. Therefore, the relation of thigh and femur as well as lower limb and tibia diameters was calculated and combined in one value. The investigation unit consisted of a standardized chair with passive knee joint movement (90-0 degrees flexion) supported by an electric motor. The position of predefined skin markers was assessed by digital camera with online transmission to a PC. The instant center pathway was then evaluated applying the Reuleaux technique based on the changes of skin marker positions. Results showed the following characteristics: small values of soft tissue ratio were represented by round or oval courses of the pathway whereas increasing ratios led to triangular and slightly increased dimensions of the courses. Varus deformity was primarily combined with an increase of the pathway's dimension and in contrast, valgus deformity showed decreased pathways. In each case, dimensions normalized after prosthesis implantation. The instant center pathway of knee joint motion showed for both patient groups characteristic phenomena. They were clearly associated with constitutional and clinical features of each patient.

Aged↗

PubMed2005

[Diagnosis specific differences in knee joint geometry. A challenge for the correct axial implantation of long stems in total knee arthroplasty].

BACKGROUND: Arthrotic deformities with changes in knee geometry can produce difficulties in implanting long stem knee prosthesis systems using intramedullary alignment. They can result in incorrect lower limb axis and prosthesis positioning. The aim of the presented study was to measure knee geometry in patients with varus and valgus gonarthrosis in order to define diagnosis related differences. METHODS: A total of 75 patients with indication for total knee arthroplasty were divided in two groups using the weight bearing lower limb axis: patients with varus gonarthrosis (n=43) and with valgus gonarthrosis (n=32). Angles and extensions, important for knee prosthesis implantation, were measured, digitalized and analyzed. The results were investigated for diagnosis specific differences. RESULTS: After regulation of the measured extension in mean femur/tibia lengths, significant diagnosis specific differences were found: femur condyles were widened towards pathologic weight bearing (P<0.044), and the mechanical tibia axis of the varus gonarthrosis group is transferred to the lateral side (P<0.046) and in projection over the lateral internal cortical substance. CONCLUSION: The significant differences in deformed arthrotic knees indicate that for an optimal postoperative result the use of standard implants is not always sufficient. Modular knee prosthesis systems can provide adequately for individual demands.

Adult↗

PubMed1997

The effect of wedged insoles on the thrust of osteoarthritic knees.

We describe a method of quantifying the lateral/medial thrust of the knee which occurs in the early phase of walking. We have used this method to evaluate the effects of wedged insoles on the lateral and medial thrust for normal knees and knees with unicompartment osteoarthritis (OA). A laterally elevated (valgus) insole decreased the lateral thrust of both normal and osteoarthritic knees. A medially elevated (varus) insole increased the lateral thrust. In 50 symptomatic knees with medial compartment OA, decreasing the lateral thrust with a valgus insole reduced pain on walking in 27. Patients whose pain was reduced by valgus insoles tended to have earlier OA and to have a significantly greater reduction in the lateral thrust than in the 23 remaining unaffected knees. A varus insole was effective in decreasing the medial thrust and reducing pain in all ten knees with lateral compartment OA. We recommend the use of valgus insoles for patients with painful early medial compartment OA and the use of varus insoles for lateral compartment OA.

Acceleration↗

PubMed2004

Anatomical and biomechanical investigations of the iliotibial tract.

Divergent descriptions of the anatomic location and biomechanical function of the iliotibial tract (IT) can be found in the literature. This study attempted to obtain exact data regarding the anatomic course and material characteristics including the biomechanical properties of this structure. The following were its aims: (1) anatomical investigations of the IT; (2) mechanical properties of the IT; (3) femoral head centralizing force of the IT and subligamentous forces in the height of the greater trochanter in different joint positions by using a custom-made measuring prosthesis and a subligamentous positioned sensor; (4) construction of a finite element model of the proximal femur including the IT and measuring the femoral neck angle under variation. The hip joints and IT in a total of 18 unfixed corpses were evaluated. We studied the anatomic relationship to surrounding structures, as well as the material properties with the help of tensile strength testing utilizing an uniaxial apparatus. During the test, a load-displacement curve was registered, documenting the maximum load and deformation of the IT. To measure the subligamentous pressure at the height of the greater trochanter, a custom-made sensor with a power-recording instrument was constructed. Furthermore, an altered hip prosthesis with a pressure gauge at the height of the femoral neck was used to measure the forces which are directed at the acetabulum. The investigations were done in neutral-0 position and ab/adduction of the hip joint of the unfixed corpse. In addition, we varied the femoral neck angle between 115 degrees and 155 degrees in 5 degrees steps. To confirm the subligamentous forces, we did the same measurements intraoperatively at the height of the greater trochanter before and after hip joint replacement in 12 patients. We constructed a finite element model of the proximal femur and considering the IT. The acquisition of the data was done at physiological (128 degrees), varus (115 degrees), and valgus (155 degrees) femoral neck angles. The influencing forces of the IT at the height of the greater trochanter and the forces at the femoral head or the acetabulum could be measured. Our anatomical investigations revealed a splitting of the IT into a superficial and a deep portion, which covers the tensor fasciae latae. The tensor fasciae latae has an insertion on the IT. The IT continues down the femur, passing over the greater trochanter without developing an actual fixation to the bone. Part of the insertion of the gluteus maximus radiates into the IT. The IT passes over the vastus lateralis and inserts at the infracondylar tubercle of the tibia or Gerdy's tubercle, at the head of the fibula, as well as at the lateral intermuscular septum. Portions also insert on the transverse and longitudinal retinaculum of the patella. Concerning the material properties of the IT, we found a structural stiffness of 17 N/mm extension on average (D = 17 N/mm). The subligamentous measurements at the height of the greater trochanter in the unfixed corpse and intraoperatively during hip joint replacement showed an increase of the forces during adduction and a decrease during abduction of the hip joint. We found thereby a maximum increase up to 106 N with 40 degrees adduction. Concerning the femoral neck angle, we can state that valgus leads to lower subligamentous forces and varus to higher subligamentous forces. The forces directed at the acetabulum, which were measured by the prosthesis with a sensor along the femoral neck, showed a decrease with varus angles and an increase with valgus angles. The highest force of 624 N was measured with 40 degrees adduction and an angle of 155 degrees. The finite element model of the proximal femur showed a sole hip joint-centralizing force of the IT of 655 N with a femoral neck angle of 128 degrees after subtraction of the gluteal muscle force and the body weight. At 115 degrees, we found an increase up to 997 N and a decrease to 438 N at 155 degrees. Concerning the resulting forces in the acetabulum, we found opposite forces in comparison with the force of the IT at the height of the greater trochanter: at 115 degrees, a femoral head-centralizing force of 1601 N; at 128 degrees, 2360 N; and at 155 degrees, 2422 N. By our investigations, we can approximately prove the hip joint-centralizing force of the IT. By variation of the femoral neck angle and the position of the hip joint, we can predict the subligamentous force of the IT and the resulting force at the femoral head or at the acetabulum. The intraoperative measurement of the subligamentous forces of the IT is a good monitoring mechanism for the persistent hip-centralizing function of the IT in the course of hip joint replacement. The surgeon has the opportunity to check the stability of the hip joint after replacement. The finite element model gives the opportunity to check the divergent relative strength by variation of the femoral neck angle and the tension of the IT. In this way, the changes in the forces induced by a displacement osteotomy could be estimated preoperatively.

Aged↗

PubMed2004

Photoelastic study of the internal and contact stresses on the knee joint before and after osteotomy.

INTRODUCTION: The treatment of knee osteoarthrosis represents a difficult task. Osteotomy is one of the treatment regimes which, in earlier times, was the only surgical procedure giving reliable mid-term results. The improvement was attributed either to the changing of the acting forces or to the so-called biological factor. The use of a photoelastic model allows the observation of the direction of the significant contact and internal stresses at every point in a single plane. MATERIALS AND METHODS: In the present study, we investigated the stress-strain situation of the knee joints in models made from 1 cm thick Araldite plates. These models reproduce tracings from anteroposterior X-ray views of monopodal loading of human knee joints. The models represent: normal knee joints, normal varus or valgus knee joint, knee joints suffering osteoarthrosis in varus or valgus, and knee joints suffering osteoarthrosis, following corrective osteotomies. The models were first loaded along the longitudinal axis with the leg in full extension, with 70 kg (body weight) and then with 140 kg, representing double the normal body weight. RESULTS: The application of longitudinal force on a normal knee joint, in full extension, results in symmetrical arrangement of trajectories in the condyles. Loading of the leg in varus or valgus produces shifting of stresses towards the inclination side. Increased contact stresses are always greater in the tibial condyles. The concentration of strain is directed towards the cortices of the loaded area. In a knee joint with osteoarthrosis, deviation of the trajectories in the condyles towards the inclination of the leg axis is observed. Also, increased contact stresses appear in the articular surfaces, on the inclination side. Isoclinics have meeting points on the loaded cortices. Supracondylar femoral osteotomy, or high tibial osteotomy, restores the axis of the leg, redistributes internal stresses (strain) in the condyles, corrects the trajectorial lines, and redistributes contact stresses in the articular surfaces towards the normal values. CONCLUSION: Correction of the femorotibial axis results in redistribution of the isochromatics, isoclinics, trajectorial lines and contact stresses. The values of the above parameters are corrected and remain closer to these of the normal knee, but in no case does the correction of all the above factors attain normal values. The change of direction of the main stresses following osteotomies towards those of the normal knee probably represents the biomechanical explanation of the way the osteotomy relieves pain and improves function.

Biomechanical Phenomena↗

PubMed2006

Asymmetry of mediolateral laxity of the normal knee.

BACKGROUND: Understanding the normal kinematics of the joints is important for reconstructive surgery. However, only a few extensive studies have been done on medial and lateral laxity of the normal knee. METHODS: Radiographs of 50 normal knees were obtained under varus and valgus stress in both extension and flexion and the relative angle of the articular surface was measured. RESULTS: In extension, the mean angle was 4.9 degrees in varus stress and 2.4 degrees in valgus stress. In flexion, the mean angle was 4.8 degrees in varus stress and 1.7 degrees in valgus stress. Lateral laxity was significantly greater than medial laxity in both extension and flexion. CONCLUSIONS: Lateral laxity may be necessary for the medial pivot movement of the normal knee. There is some disagreement regarding the importance of pursuing the perfect rectangular gaps during total knee arthroplasty (TKA). The methods for measuring the tension of soft tissues during the operation are not accurate and do not always reflect the postoperative tensions of dynamic phases, such as walking and standing. Slight lateral laxity can be accepted with TKA, and further studies are necessary to determine whether prosthesis lift-off occurs in the replaced knee with slight lateral laxity similar to that in the normal knee.

Adult↗

PubMed2004

Evaluation of knee and hindfoot alignment before and after total knee arthroplasty: a prospective analysis.

A prospective study on 100 cases was performed to evaluate the effect of total knee arthroplasty (TKA) on hindfoot alignment, and to compare knee alignment and hindfoot alignment preoperatively and postoperatively. Preoperative knee alignment ranged from 30 degrees of valgus to 13 degrees of varus. Postoperative knee alignment ranged from 14 degrees of valgus to 0 degrees. Preoperative foot alignment ranged from 22 degrees of valgus to 13 degrees of varus. Postoperative foot alignment ranged from 22 degrees of valgus to 11 degrees of varus. Preoperative knee alignment did not correlate with foot alignment (P =.182). Postoperative knee alignment and foot alignment also showed no correlation (P =.222). Preoperative and postoperative knee alignment were correlated, as expected (P =.000). Notably, hindfoot alignment was changed by knee arthroplasty, and changed in a predictable fashion (P=.000). The alignment of the foot before knee arthroplasty was the largest contributing factor to the hindfoot alignment after arthroplasty of the knee. Hindfoot alignment was changed by TKA, and changed in a predictable fashion.

Arthroplasty, Replacement, Knee↗

PubMed2004

Lateral retinacular release as a function of femoral component rotation in total knee arthroplasty.

A consensus exists in the orthopaedic community that proper rotational placement of components may reduce the need for lateral release. This study compares the rates and results of lateral release before and after femoral component placement was defined by the transepicondylar axis (TEA). Between 1990 and 1991, 104 primary total knee arthroplasties (TKA) were reviewed during which equal amounts of bone from the posterior femoral condyles were removed. In this group, the lateral release incidence was 24% for varus deformities and 33% for valgus deformities. When the femoral component was externally rotated approximating the TEA, a review of 246 primary TKAs performed between 1998 and 1999 showed lateral release rates of 7% in varus deformities and 29% in valgus deformities. This study documents the statistically significant decline in the lateral release rate with external rotation of the femoral component during TKA in varus deformities (P<.0001), and a decreasing trend in valgus knees (P =.09).

Adult↗

PubMed2004

The initial stability of an exeter femoral stem after impaction bone grafting in combination with segmental defect reconstruction.

Bone impaction grafting of the femur is associated with more complications when segmental defects are present. The effect of segmental defect repair on initial stem stability was studied in an in vitro study with fresh-frozen goat femora. A standardized medial segmental defect was reconstructed using a cortical strut or a metal mesh. As controls, we used intact femora and femora with a nonreconstructed defect. In all 4 groups, impacted bone grafting was performed in combination with a cemented Exeter stem. Each group contained 5 femora. Reconstructions were dynamically loaded up to 1,500 N. Migration was measured with Roentgen stereophotogrammetric analysis. All cases with a nonreconstructed segmental defect failed into excessive varus rotation. None of the femora with a reconstructed defect failed. Cortical struts and metal meshes were equally effective in creating a stable stem construction (varus rotation, 2.89 +/- 2.27 and 2.27 +/- 0.57, respectively). Reconstructions with a metal mesh were more reproducible, although the obtained stability was significantly lower (P<.01) when compared with impaction grafting in an intact femur (varus rotation, 0.58 +/- 0.36).

Animals↗

PubMed2006

Patient, implant, and alignment factors associated with revision of medial compartment unicondylar arthroplasty.

The investigators reviewed 245 fixed-bearing unicondylar arthroplasties that one surgeon performed as treatment of medial compartment osteoarthritis between 1988 and 1997 using a variety of cemented metal-backed tibial components and gamma-irradiated-in-air polyethylene bearings. Multivariate statistical analysis was used to evaluate how the event of revision was influenced by 3 patient factors, 3 implant factors, and 7 factors assessed from preoperative and early postoperative radiographs. Five factors were statistically associated with revision: (younger) patient age, (thinner) tibial component initial thickness, (longer) polyethylene shelf age, (lesser) angular reduction of medial tibial plateau varus, and (more varus) postoperative hip-knee-ankle angle. Besides illustrating deleterious consequences of using gamma-irradiated-in-air polyethylene in medial unicompartmental arthroplasty, our results support reducing varus angulation of the medial tibial plateau and knee at surgery.

Age Factors↗