Letter to the Editor: The ACL in the Arthritic Knee: How Often is it Present and Can Preoperative Tests Predict its Presence?
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- Cite this article as:
- van den Dorpel, A. & Swart, N.M. Clin Orthop Relat Res (2013) 471: 1054. doi:10.1007/s11999-012-2678-8
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To the Editor
With great interest we read the article by Johnson et al. regarding the presence of the ACL in patients with arthritic knees . Limitations in function after TKA are common. Because of the increasing need for TKA, it is important to determine the cause of patients’ dissatisfaction. Johnson et al. concentrated on the kinematics of the knee, and more specifically the presence of the ACL preoperatively. They concluded the best way to determine if the ACL is present is to combine MRI with the Lachman test. However, we had some difficulties interpreting the results because Johnson et al. did not mention whether the researchers who performed the observation during the operation were blinded for the results of the Lachman test. If this is not the case, the results possibly are biased and the observed relationships may be overestimated.
Furthermore, we question why the Lachman test was performed after induction of anesthesia. It seems more logical and clinically relevant to perform this test at the outpatient clinic before surgery so that the surgeon can choose the right implants and instruments in advance.
Johnson et al. assessed preoperative MRIs from 100 of the 200 included patients. It is unclear why and on what basis the authors’ selection of 100 of the total of 200 included patients was made. Was this a representative selection?
In the Results section, part of the answer to the 5th question (did ACL status depend on age or sex?) is missing. Does the ACL status depend on sex? Unfortunately it is only reported that patients with an intact ACL at the time of surgery were older.
Finally, there are inconsistencies and missing data in Table 1. The number of patients with absent intraoperative ACL integrity is missing. In the same table we found that the 194 negative Lachman tests should be 184 to make a total of 100%.
We would appreciate the authors’ responses to our questions.