2015 ISAKOS Biennial Congress ePoster #1204
Clinical Outcome After Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction for Knee Hyperextension
Kazuhisa Hatayama, MD, PhD, Maebashi, Gunma JAPAN
Kenishi Saito, MD, PhD, Maebashi, Gunma JAPAN
Masanori Terauchi, MD, Gunma-Ken JAPAN
Hiroshi Higuchi, MD, PhD, Maebashi, Gunma JAPAN
Gunma Chuo Hospital, Maebashi, Gunma, JAPAN
FDA Status Cleared
Summary: Although anatomic double-bundle anterior cruciate ligament reconstruction for knee hyperextension obtained the same postoperative anterior and rotational stability as for normal knees, it resulted in some loss of extension remaining after surgery.
A negative effect of knee hyperextension on anterior cruciate ligament reconstruction (ACLR) is that graft roof impingement might be increased, which results in graft deterioration and loss of extension (LOE). Although recent studies on anatomic ACLR showed that it eliminated the concern about roof impingement, to date, there have been no clinical studies investigating the postoperative outcome after anatomic ACLR for knee hyperextension. The purpose of this study was to compare with knee stability, postoperative LOE and graft integrity after anatomic ACLR between normal knees and knee hyperextension.
For 100 patients who underwent anatomic double-bundle ACLR using semitendinosus tendon, we evaluated side-to-side difference (SSD) in anterior tibial translation on stress radiographs, and rotational stability, assessed by the pivot-shift test, 2 years after surgery. LOE was evaluated on lateral radiographs of both knees in full extension, and graft integrity was assessed during second-look arthroscopy. According to the Beighton and Honan criteria, patients with an extension angle of the contralateral uninjured knee of =10° comprised the normal knee group (N group: 58) and those with an extension angle of >10° comprised the knee hyperextension group (H group: 42).
Mean extension angles in the N and H groups were 5.8 ± 2.9° and 14.7 ± 3.0°, respectively. The mean SSD in anterior translation in the N and H groups were 2.2 ± 2.9 and 2.8 ± 2.9 mm, respectively, with no significant difference. Positive ratios on the pivot-shift test in the N and H groups were 7 of 58 knees and 8 of 42 knees, respectively, with no significant difference. Mean LOE in the N and H groups were -0.7 ± 3.7° and 1.3 ± 3.3°, respectively, with a significant difference (P =0.007). In the H group, there was a significant positive correlation between extension angle of the contralateral knee and LOE (r = .33; P = .04). During second-look arthroscopy, 6 of 58 knees in the N group and 13 of 42 knees in the H group had superficial graft laceration, which were significantly different (P = 0.01).
We found that knee stability after anatomic ACLR was not significantly different between groups. However, LOE in knee hyperextension was significantly larger than that in normal knees, and graft integrity of knee hyperextension was inferior to that in normal knees. Previous MRI study demonstrated that mean extension angle of the beginning of impingement in native ACL was approximately 6° and the ACL stretched out in hyperextension after contacting the notch. This indicates that viscoelasticity of the native ACL facilitates full hyperextension. Our study demonstrated that the patients with a contralateral knee with a larger extension angle retained larger LOE in the H group. Even if the anatomic ACLR restored the physiologic roof impingement, reconstructed ACL graft may not be able to acquire the same viscoelastic properties as native ACL throughout the process of remodeling. For knee hyperextension, it may be that the ACL graft should be fixed at a more extended angle of the knee to prevent LOE.