J Korean Orthop Assoc.  2019 Jun;54(3):254-260. 10.4055/jkoa.2019.54.3.254.

Relationship between Knee Function at 1 Year Postoperation and Gap Difference (90° Flexion Gap–Extension Gap) in Total Knee Replacement

• Cho MR
• Do JS
• Kim KT
• Choi WK

• KMID: 2450145
• DOI: http://doi.org/10.4055/jkoa.2019.54.3.254

Abstract

PURPOSE
To evaluate the relationship between the knee function at 1 year postoperation and the gap difference (90° flexion gap-extension gap) in total knee replacement.
MATERIALS AND METHODS
Eighty-two consecutive osteoarthritis knees that underwent primary total knee replacement using navigation from March 2017 June 2017 were evaluated prospectively. The gap was measured using navigation after reducing the patella with towel clips. After checking the average values of the medial and lateral gaps at extension and 90° flexion knee, the gap difference (90° flexion gap-extension gap) was calculated. The knees were divided into three groups according to the gap difference (gap difference<0 mm, 0 mm≤gap difference<2 mm, 2 mm≤gap difference). The Knee Society score (KSS) and maximal knee flexion were compared at 1 year postoperation among three groups.
RESULTS
The numbers of knees according to groups were 37, 29, and 16 knees in regular order. The average of the KSS knee, KSS function, and maximal knee flexion at the 1-year follow-up were 81.21±8.31, 71.34±9.84, and 126.48°±7.28°, respectively. No statistically significant difference in KSS was observed among the 3 groups. The third group (2 mm≤gap difference) showed a larger maximal knee flexion than the other groups in the Mann-Whitney test.
CONCLUSION
The group of total knee replacement (2 mm≤90° flexion gap-extension gap) showed larger maximal knee flexion than the other groups at the 1-year follow-up in statistics.

Keyword

total knee replacement; gap; flexion

MeSH Terms

Arthroplasty, Replacement, Knee*
Follow-Up Studies
Knee*
Osteoarthritis
Patella
Prospective Studies

Figure

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  Figure 1. To obtain post total knee arthroplasty status gap, gap after patella reduction was measured using towel clips.

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  Figure 2. Soft tissue release and extension-flexion gaps were controlled by viewing the navigation screen displacing the extension and flexion gaps. AP, anteroposterior.

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  Figure 3. Distribution of the gap differences (90˚ flexion gap–extension gap).

Reference

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