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Flexion Gap Measured in 45 Degrees and 90 Degrees of Hip Flexion Positions during Total Knee Arthroplasty: Measurement by Navigation System.

Lee JK, Chung KS, Kim BH, Choi CH - Knee Surg Relat Res (2014)

Bottom Line: After posterior cruciate ligament sacrificing, complete soft tissue balancing, and fixation of all components with cement, the flexion gaps were measured with the patello-femoral joint reduced.The flexion gaps showed no significant (p>0.05) differences between the two different hip flexion positions.Therefore, soft tissue balancing and polyethylene thickness should not be affected by hip flexion positions during TKA.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, Hanyang University College of Medicine, Seoul, Korea.

ABSTRACT

Purpose: To evaluate the influence of thigh weight in different hip flexion positions on the knee flexion gap in total knee arthroplasty (TKA).

Materials and methods: We evaluated 20 patients (25 knees) with osteoarthritis of the knee that underwent TKA using a navigation system from May 2010 to April 2011. After posterior cruciate ligament sacrificing, complete soft tissue balancing, and fixation of all components with cement, the flexion gaps were measured with the patello-femoral joint reduced. Medial and lateral flexion gaps were measured separately in both the 90°-90° and 45°-90° flexion positions of the hip-knee joints.

Results: The medial and lateral flexion gaps in the 45°-90° flexion position of the hip-knee joints were 13.02±2.17 mm and 13.12±2.21 mm, respectively. The medial and lateral flexion gaps in the 90°-90° flexion position were 12.92±2.03 mm and 13.08±2.29 mm, respectively. The flexion gaps showed no significant (p>0.05) differences between the two different hip flexion positions.

Conclusions: Flexion gaps in TKA were not influenced by hip flexion positions (45° or 90° of flexion). Therefore, soft tissue balancing and polyethylene thickness should not be affected by hip flexion positions during TKA.

No MeSH data available.


Related in: MedlinePlus

Schematic representation of flexion gap measurement. When the hip is in 90° flexion, the weight of the thigh may not affect the flexion gap (A). When the hip is in 45° flexion, the weight of the thigh would possibly affect the flexion gap (B).
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Figure 1: Schematic representation of flexion gap measurement. When the hip is in 90° flexion, the weight of the thigh may not affect the flexion gap (A). When the hip is in 45° flexion, the weight of the thigh would possibly affect the flexion gap (B).

Mentions: All the operations were performed by the same surgeon using a medial parapatellar approach with the hip and knee joints placed in 45° flexion position and a tourniquet applied. After joint exposure, infrared camera trackers were anchored to the distal femur and the anteromedial aspect of the proximal tibia, and the center of the hip located through rotational exercises was registered. Subsequently, locations of the anatomical structures in the femur and tibia were registered using a probe in the Ci knee system. Under the guidance of the Ci knee system using the gap technique, tibial resection was performed with the goal of creating 0° of varus-valgus angulation in the coronal plane and 4° of posterior slope in the sagittal plane. Femoral resection was performed to make the anatomical axis be in 6° valgus relative to the mechanical axis. With a trial prosthesis positioned in place, the mechanical axis of the lower limb, extension and flexion gap balance, and medial-lateral soft-tissue balance were assessed using navigation system. When proper bone resection and soft-tissue balance were considered achieved, the thickness of the polyethylene insert was determined according to the size of the extension gap and the flexion gap measured with the hip in 45° flexion. The implants were fixed using bone cement. Patella tracking was confirmed with the patella reduced using the no thumb technique. Lateral retinacular release was not considered necessary in any of the cases. After tourniquet release, with the patella reduced, medial and lateral flexion-extension gaps and midflexion gaps (45° of knee flexion position) were measured with the hip in 90° flexion and 45° flexion each using navigation system (Fig. 1). The distances from the proximal tibial cut surface to a site inferior to the femoral component (extension gap) and to the posterior border of the femoral component (flexion gap) were measured using a navigation probe without additional application of traction. Values measured in 0.5 mm increments were recorded for analysis when three orthopedic surgeons agreed on the flexion angles of the hip and knee joints and knee joint gaps presented on the navigation screen.


Flexion Gap Measured in 45 Degrees and 90 Degrees of Hip Flexion Positions during Total Knee Arthroplasty: Measurement by Navigation System.

Lee JK, Chung KS, Kim BH, Choi CH - Knee Surg Relat Res (2014)

Schematic representation of flexion gap measurement. When the hip is in 90° flexion, the weight of the thigh may not affect the flexion gap (A). When the hip is in 45° flexion, the weight of the thigh would possibly affect the flexion gap (B).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4061410&req=5

Figure 1: Schematic representation of flexion gap measurement. When the hip is in 90° flexion, the weight of the thigh may not affect the flexion gap (A). When the hip is in 45° flexion, the weight of the thigh would possibly affect the flexion gap (B).
Mentions: All the operations were performed by the same surgeon using a medial parapatellar approach with the hip and knee joints placed in 45° flexion position and a tourniquet applied. After joint exposure, infrared camera trackers were anchored to the distal femur and the anteromedial aspect of the proximal tibia, and the center of the hip located through rotational exercises was registered. Subsequently, locations of the anatomical structures in the femur and tibia were registered using a probe in the Ci knee system. Under the guidance of the Ci knee system using the gap technique, tibial resection was performed with the goal of creating 0° of varus-valgus angulation in the coronal plane and 4° of posterior slope in the sagittal plane. Femoral resection was performed to make the anatomical axis be in 6° valgus relative to the mechanical axis. With a trial prosthesis positioned in place, the mechanical axis of the lower limb, extension and flexion gap balance, and medial-lateral soft-tissue balance were assessed using navigation system. When proper bone resection and soft-tissue balance were considered achieved, the thickness of the polyethylene insert was determined according to the size of the extension gap and the flexion gap measured with the hip in 45° flexion. The implants were fixed using bone cement. Patella tracking was confirmed with the patella reduced using the no thumb technique. Lateral retinacular release was not considered necessary in any of the cases. After tourniquet release, with the patella reduced, medial and lateral flexion-extension gaps and midflexion gaps (45° of knee flexion position) were measured with the hip in 90° flexion and 45° flexion each using navigation system (Fig. 1). The distances from the proximal tibial cut surface to a site inferior to the femoral component (extension gap) and to the posterior border of the femoral component (flexion gap) were measured using a navigation probe without additional application of traction. Values measured in 0.5 mm increments were recorded for analysis when three orthopedic surgeons agreed on the flexion angles of the hip and knee joints and knee joint gaps presented on the navigation screen.

Bottom Line: After posterior cruciate ligament sacrificing, complete soft tissue balancing, and fixation of all components with cement, the flexion gaps were measured with the patello-femoral joint reduced.The flexion gaps showed no significant (p>0.05) differences between the two different hip flexion positions.Therefore, soft tissue balancing and polyethylene thickness should not be affected by hip flexion positions during TKA.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, Hanyang University College of Medicine, Seoul, Korea.

ABSTRACT

Purpose: To evaluate the influence of thigh weight in different hip flexion positions on the knee flexion gap in total knee arthroplasty (TKA).

Materials and methods: We evaluated 20 patients (25 knees) with osteoarthritis of the knee that underwent TKA using a navigation system from May 2010 to April 2011. After posterior cruciate ligament sacrificing, complete soft tissue balancing, and fixation of all components with cement, the flexion gaps were measured with the patello-femoral joint reduced. Medial and lateral flexion gaps were measured separately in both the 90°-90° and 45°-90° flexion positions of the hip-knee joints.

Results: The medial and lateral flexion gaps in the 45°-90° flexion position of the hip-knee joints were 13.02±2.17 mm and 13.12±2.21 mm, respectively. The medial and lateral flexion gaps in the 90°-90° flexion position were 12.92±2.03 mm and 13.08±2.29 mm, respectively. The flexion gaps showed no significant (p>0.05) differences between the two different hip flexion positions.

Conclusions: Flexion gaps in TKA were not influenced by hip flexion positions (45° or 90° of flexion). Therefore, soft tissue balancing and polyethylene thickness should not be affected by hip flexion positions during TKA.

No MeSH data available.


Related in: MedlinePlus