Flexion gap preparation opens the extension gap in posterior cruciate ligament-retaining TKA

Purpose Increasing the tibial slope is often performed if the flexion gap is narrower than the extension gap. The main hypothesis of this study is that increasing the tibial slope coincidentally enlarges the extension gap. Methods Twenty formalin-fixed cadaveric knees were obtained for study. After CT in full extension and 90°flexion, the data of each specimen were entered into a standardized coordinate system and virtual bone cuts were performed with incrementally increasing the posterior slope. Gaps were measured at tibiofemoral contact points in 90°-flexion and full extension in the medial and lateral compartment. Results Increasing the tibial slope did significantly widen both the extension and the flexion gaps (p<0.001). In extension, the opening rates, i.e. the gap increase per degree of slope increase, were equal medially and laterally (0.5 mm ±0.1) medial vs 0.6 mm (±0.0) lateral), whereas in flexion the lateral gap did open significantly more than the medial one (0.6 mm ±0.1) medial vs 0.9 mm (±0.1) lateral (p<0.001), resulting in a significantly greater flexion gap laterally.Conclusions Increasing the tibial slope beyond the preoperative planning in order to widen a tight flexion gap intra-operatively is not recommended as doing so will increase the extension gap simultaneously and will make the medial and lateral flexion gaps unequal.

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“…Many surgeons strive to produce extension and flexion gaps that are of equal magnitude and/or symmetrical [2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Influence of tibial slope on extension and flexion gaps in total knee arthroplasty: increasing the tibial slope affects both gaps

Nowakowski

Kamphausen

Pagenstert

et al. 2014

International Orthopaedics (SICOT)

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“…15,16 Even preparation of the flexion gap can influence the extension gap. Minoda et al 17 found that preparation of the flexion gap resulted in significant widening of the extension gap during cruciate-retaining TKA. Also, Sugama et al 18 showed a significant increase in the width of the extension gap, and hypothesized that the removal of the posterior femoral condyle and osteophytes loosens the posterior capsule and thus affects the extension gap.…”

mentioning

confidence: 99%

Measurement of knee joint gaps without bone resection: “Physiologic” extension and flexion gaps in total knee arthroplasty are asymmetric and unequal and anterior and posterior cruciate ligament resections produce different gap changes

Nowakowski

Majewski

Müller‐Gerbl

et al. 2011

Journal Orthopaedic Research

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General agreement is that flexion and extension gaps should be equal and symmetrical in total knee arthroplasty (TKA) procedures. However, comparisons using a standard TKA approach to normal knee joints that have not undergone bone resection are currently unavailable. Since bony preparation can influence capsule and ligament tension, our purpose was to perform measurements without this influence. Ten normal cadaveric knees were assessed using a standard medial parapatellar TKA approach with patellar subluxation. Gap measurements were carried out twice each alternating 100 and 200 N per compartment using a prototypical forcedetermining ligament balancer without the need for bony resection. Initial measurements were performed in extension, followed by 908 of flexion. The ACL was then resected, and finally the PCL was resected, and measurements were carried out in an analogous fashion. In general, the lateral compartment could be stretched further than the medial compartment, and the corresponding flexion gap values were significantly larger. ACL resection predominantly increased extension gaps, while PCL resection increased flexion gaps. Distraction force of 100 N per compartment appeared adequate; increasing to 200 N did not improve the results. ß

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“…These procedures were difficult to perform before femoral osteotomies. Minoda et al assessed the three different extension gaps before and after femoral osteotomy of the posterior condyle, and after removal of femoral posterior osteophytes [33]. In the future, we need to further investigate the effect of these procedures at flexion as well as at extension.…”

Section: Discussionmentioning

confidence: 98%

“…In the procedure using the gap technique, the extension gap has been reported to be wider after resection of the posterior femoral condyle and removal of the osteophytes on the posterior aspect of the femur, a procedure performed to reestablish the posterior capsular recess in CR TKA [33] as well as PS TKA [31]. Therefore, if the flexion gap is matched to the previously prepared extension gap, the extension gap will increase, and the flexion gap will become smaller than the extension gap.…”

Section: Discussionmentioning

confidence: 98%

Soft tissue balance using the tibia first gap technique with navigation system in cruciate-retaining total knee arthroplasty

Matsumoto

Muratsu²,

Kubo

et al. 2011

International Orthopaedics (SICOT)

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Flexion gap preparation opens the extension gap in posterior cruciate ligament-retaining TKA

Cited by 24 publications

References 9 publications

Influence of tibial slope on extension and flexion gaps in total knee arthroplasty: increasing the tibial slope affects both gaps

Influence of tibial slope on extension and flexion gaps in total knee arthroplasty: increasing the tibial slope affects both gaps

Measurement of knee joint gaps without bone resection: “Physiologic” extension and flexion gaps in total knee arthroplasty are asymmetric and unequal and anterior and posterior cruciate ligament resections produce different gap changes

Soft tissue balance using the tibia first gap technique with navigation system in cruciate-retaining total knee arthroplasty

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