Introduction. Unicompartmental knee arthroplasty(UKA) has become a popular treatment alternative when one compartment of the knee is affected. Excellent intermediate results have been reported in association with the Miller-Galante unicompartmental implant. These excellent results are based on the development of the implants and the stringent patients selection. The functional cruciate ligaments has been a prerequisite for patients undergoing UKA. However, UKA can be one of the procedures in elderly patiants with deficient anterior cruciate ligaments(ACL) but with no symptoms of instability. The purpose of this report is to determine the clinical results after UKA in patients with ACL-deficient knees and compared those after UKA in ACL-intact knees. Patients and Methods. We identified 332 cases operated from May 2000 to April 2013 whose ACL were evaluated before the operation by MRI., and classified into ACL-deficient group and ACL-intact group. Fixed-bearing Miller-Galante Unicompartmental Knee System or Zimmer Unicompartmental High-Flex Knee Sytem was implanted in all patients. ACL-deficient group included 17 men and 68 women who had an average age of 79 years(range, 70–91 years) at the time of the operation. The underlying diagnosis was osteoarthritis for 77 knees and osteonecrosis for 8 knees. ACL-intact group included 49 men and 198 women who had an average age of 77 years(range, 60–88 years) at the time of the operation. The underlying diagnosis was osteoarthritis for 176 knees and osteonecrosis for 71 knees. Followup for ACL-deficient group was 3.5 years(1–8.8years), and 3.6years (1–13.2years) for ACL-intact group. Results. Japanese Orthopaedic Association score improved from 46.7points preoperatively to 76.5 points at the time of the latest followup in ACL deficient group, and 49.6 points to 81.5 points in ACL-intact group. 7 knees(8.2%) had a partial radiolucent line around the tibial component in ACL-deficient group, and 30 knees(12.6%) had a partial radiolucent line around the tibial component(30knees) or femoral component(one knee) in ACL-intact group, all of these radiolucent lines were <2mm in thickness and remained stable over time. Two knees(2.3%) in ACL-deficient group and five knees(2.0%) in ACL-intact group were revised because of progression of arthritis in the lateral tibiofemoral or patellofemoral components. All of the components in revised knees were well fixed and no polyethylene wear was seen at the time of revision. All of these results between two groups were not significantly different. Conclusion. Controversy exists about whether a functional ACL is necessary to achieve success with UKA. In classical indication, UKA should not be done in patients with symptoms of ACL instability. In elderly active patient with deficient ACL, we should prefer total knee arthroplasty. But UKA should judiciously be done in eldery patients with deficient ACL whose activity is low but with no symptoms of instability

Between 1993 and 1994, 891 patients underwent primary anterior cruciate ligament (ACL) reconstruction. A total of 48 patients had undergone bilateral ACL reconstruction and 42 were available for review. These patients were matched to a unilateral ACL reconstruction control group for gender, age, sport of primary injury, meniscal status and graft type. At 15-year follow-up a telephone interview with patients in both groups was performed. The incidence of further ACL injury was identified through structured questions and the two groups were compared for the variables of graft rupture or further ACL injury, family history of ACL injury, International Knee Documentation Committee (IKDC) subjective score and activity level.

There were 28 male and 14 female patients with a mean age of 25 years (13 to 42) at the time of first ACL injury. Subsequent further ACL injury was identified in ten patients (24%) in the bilateral ACL reconstruction study group and in nine patients (21%) in the unilateral ACL reconstruction control group (p = 0.794). The mean time from bilateral ACL reconstruction to further ACL injury was 54 months (6 to 103). There was no significant difference between the bilateral ACL reconstruction study group and the matched unilateral ACL reconstruction control group in incidence of further ACL injury (p = 0.794), family history of ACL injury (p = 0.595), IKDC activity level (p = 0.514), or IKDC subjective score (p = 0.824).

After bilateral ACL reconstruction the incidence of graft rupture and subjective outcomes were equivalent to that after unilateral ACL reconstructions.

Cite this article: Bone Joint J 2013;95-B:798–802.