title: The necessity of clinical application of tibial reduction for detection of underestimated posterolateral rotatory instability in combined posterior cruciate ligament and posterolateral corner deficient knee.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the usefulness of tibial reduction during dial test for clinical detection of underestimated posterolateral rotatory instability (PLRI) in combined posterior cruciate ligament (PCL)-posterolateral corner (PLC) deficient knee in terms of external rotation laxity and clinical outcomes.
  
  
  METHODS
  Twenty-one patients who classified as grade I PLRI using dial test with subluxated tibia, but classified as grade II with tibial reduction evaluated retrospectively. The mean follow-up was 39.3 months (range 24-61 months). Each patient was evaluated by the following variables: posterior translation and varus laxity on radiograph, KT-1000 arthrometer, dial test (reduced and subluxated position), International Knee Documentation Committee, Orthopädische Arbeitsgruppe Knie scoring system and Tegner activity scale.
  
  
  RESULTS
  There were significant improvements in posterior tibial translation (8.6 ± 2.0 to 2.1 ± 1.0 mm; P < 0.001), varus laxity (3.3 ± 1.3 to 1.4 ± 0.5 mm; P < 0.001) and external rotation (13.2° ± 0.8° to 3.6° ± 1.1° at 30°, 13.3° ± 0.9° to 3.6° ± 0.9° at 90°; P < 0.001). The clinical scores were improved significantly at the last follow-up (P < 0.001). The external tibial rotation during dial test with tibial reduction increased from 6.8° ± 0.9 to 13.2° ± 0.8° at 30° of knee flexion, from 7.0° ± 0.8° to 13.3° ± 0.9° at 90° (P < 0.001).
  
  
  CONCLUSIONS
  The clinical application of reduction of posteriorly subluxated tibia during the dial test was essential for an appropriate treatment of underestimated PLRI in combined PCL-PLC deficient knee.
  
  
  METHODS
  Retrospective case series, Level IV.
authors: Department of Orthopaedic Surgery, Chung-Ang University School of Medicine, Seoul, Korea.
authors: Han-Jun
authors: HJ
authors: Lee
authors: Department of Orthopedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-dong 50, Gangnam-gu, Seoul, 135-710, Korea. whybe1122@gmail.com.
authors: Yong-Beom
authors: YB
authors: Park
authors: Department of Orthopaedic Surgery, Chung-Ang University School of Medicine, Seoul, Korea.
authors: Young-Bong
authors: YB
authors: Ko
authors: Department of Orthopaedic Surgery, Chung-Ang University School of Medicine, Seoul, Korea.
authors: Seong-Hwan
authors: SH
authors: Kim
authors: Department of Orthopaedic Surgery, Chung-Ang University School of Medicine, Seoul, Korea.
authors: Hyeok-Bin
authors: HB
authors: Kwon
authors: Department of Orthopaedic Surgery, Guro TnTn Hospital, Seoul, Korea.
authors: Dong-Seok
authors: DS
authors: Yu
authors: Department of Orthopaedic Surgery, Hyundae General Hospital, Namyangju-si, Korea.
authors: Young-Bok
authors: YB
authors: Jung
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000534:rehabilitation / Q000601:surgery; D007718:Knee Injuries / Q000175:diagnosis* / Q000534:rehabilitation / Q000601:surgery; D065466:Lysholm Knee Score; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000379:methods*; D016119:Posterior Cruciate Ligament / Q000293:injuries / Q000601:surgery*; D011184:Postoperative Period; D012189:Retrospective Studies; D012399:Rotation; D013977:Tibia / Q000601:surgery*
keywords: Dial test; Posterior cruciate ligament; Posterolateral rotator instability; Tibial reduction