The incidence and variation of tunnel enlargement after anterior cruciate ligament reconstruction / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the incidence and variation of tunnel enlargement after anterior cruciate ligament (ACL) reconstruction.</p><p><b>METHODS</b>ACL reconstructions using hamstring tendons were performed in 58 patients (58 knees) in the study. MRI scans were taken in a consistent manner at 1, 3, 6, 12 and 24 months after surgery to measure tibial and femoral tunnel expansion.</p><p><b>RESULTS</b>Femoral tunnel enlargement was observed in 9 knees (9/58, 15.5%); Tibial tunnel enlargement was found in 12 knees (12/58, 20.7%). Of those with enlarged bone tunnels, there was no significant difference of tunnel diameters between 1 and 3 months after surgery (P>0.05). Six, 12 and 24 months postoperatively, the average tunnel diameters were larger than those of 1 or 3 months after surgery (P<0.05), however, no significant difference was found in between the tunnel diameters 6, 12 and 24 months postoperatively either (P>0.05).</p><p><b>CONCLUSION</b>Tunnel expansion mainly occurs during 3 to 6 months after surgery, and it remains basically unchanged between 12 and 24 months postoperatively.</p>

Effect of increased posterior tibial slope or partial posterior cruciate ligament release on knee kinematics of total knee arthroplasty / 中华外科杂志

<p><b>OBJECTIVE</b>To compare the effects of increased posterior tibial slope or partial posterior cruciate ligament (PCL) release on knee kinematics of total knee arthroplasty (TKA).</p><p><b>METHODS</b>Anteroposterior laxity, rotational laxity, varus and valgus laxity and maximum flexion angle were evaluated in 6 normal cadaver knees and the knees after TKA at flexion 0 degrees , 30 degrees , 60 degrees , 90 degrees and 120 degrees . Then the femoral prosthesis was shifted 5 mm posteriorly to simulate the tightly implanted knee. The same tests were performed on the tightly implanted knees. After that, the posterior tibial slope was increased 4 degrees or the PCL was partially released, and the same tests were made as in the normal knees respectively. Statistical analysis of the results was made using student's t test.</p><p><b>RESULTS</b>Anteroposterior laxity, rotational laxity and varus and valgus laxity of the tightly implanted knees at flexion 30 degrees , 60 degrees , 90 degrees and 120 degrees were significantly less than those of the normal TKA knees (P < 0.05). Compared with the tightly implanted knees, anteroposterior laxity, rotational laxity and varus and valgus laxity at flexion 30 degrees , 60 degrees , 90 degrees and 120 degrees significantly improved after increased 4 degrees posterior tibial slope (P < 0.05); in the partial PCL released group, anteroposterior laxity at flexion 30 degrees , 60 degrees , 90 degrees and 120 degrees was significantly improved (P < 0.05), varus and valgus laxity was significantly improved only at flexion 90 degrees (P < 0.05), and rotational laxity was significantly improved at flexion 30 degrees , 60 degrees and 90 degrees (P < 0.05). Compared with PCL released group, varus and valgus laxity at flexion 30 degrees , 60 degrees and 90 degrees and rotational laxity at flexion 0 degrees , 30 degrees , 60 degrees and 90 degrees were significantly improved in the group of increased 4 degrees posterior tibial slope (P < 0.05). Maximum flexion angle of the tightly implanted knee (120.4 degrees ) was less than that of the normal TKA knees (130.3 degrees , P < 0.05) and that of increased 4 degrees posterior tibial slope group (131.1 degrees , P < 0.05). There was no significant difference at the maximum flexion angle between the increased 4 degrees posterior tibial slope group and the PCL released group (131.1 degrees vs 124.0 degrees , P = 0.0816).</p><p><b>CONCLUSIONS</b>Anteroposterior laxity, varus and valgus laxity, rotational laxity and maximum flexion angle of the tightly implanted knees are less than those of the normal TKA knees. After increased 4 degrees posterior tibial slope, these indexes are improved significantly. Partial PCL released can significantly improve the anteroposterior laxity and had less effect on the varus and valgus laxity, rotational laxity and maximum flexion angle. So, a knee that is tight in flexion can be more likely to be corrected by increasing posterior tibial slope than by partially releasing PCL.</p>