Morgan C D, Kalmam V R, Grawl D M
Delaware Orthopaedic Center, Wilmington 19810, USA.
Arthroscopy. 1995 Dec;11(6):647-59. doi: 10.1016/0749-8063(95)90104-3.
The purpose of this study was to determine the effect, if any, that varying the distal testing position (tibial level) has on isometry data produced with a common anatomic proximal testing position at the native anterior cruciate ligament (ACL) origin. During ACL reconstruction in 25 knees, in vivo isometry measurements were recorded using two different isometry testing methods, which differed in the tibial level of the distal fixation testing point. Method 1 tested distally at a point 13 cm peripheral to the native ACL insertion on a vector in line with the tibial tunnel. Method 2 tested distally at a point central in the native ACL insertion at the level of the intercondylar floor. All tibial tunnels were standardized with similar sagittal tunnel-plateau angles and similar tunnel lengths. The proximal testing point was standardized at a point that was anatomically located at or near the central ACL origin 7 mm anterior to "over the top" in all knees. Using these methods, length changes between the proximal and distal testing points were recorded in each knee with each testing method, with the knee ranged from 70 degrees of flexion to full extension and from 70 degrees to 140 degrees of flexion. From these data, a total excursion from 0 degree to 140 degrees of flexion was calculated. A nonanatomic distal testing point (Method 1) produced a 6 mm +/- 1 mm total excursion, whereas anatomic testing points (Method 2) in the same knees produced a 1 mm +/- 1 mm total excursion. From these data, the authors conclude that the tibial level of the distal isometry testing point has a significant effect on the resultant isometry measurement such that anatomic testing points are most isometric. Isometers that produce data between nonanatomic testing points should not be used to position tunnels for ACL reconstruction and should not be used to assume the elongation forces an ACL substitute will see when fixed at different points. Conversely, the clinical relevance of this study is that both anatomic graft position and anatomic graft fixation position are important and, when achieved, should result in minimal graft elongation with early postoperative range of motion, leading to a more stable long-term result.
本研究的目的是确定改变远端测试位置（胫骨水平）对在天然前交叉韧带（ACL）起点处采用常见解剖学近端测试位置所产生的等长数据是否有影响（若有影响则确定其影响程度）。在25例膝关节的ACL重建过程中，使用两种不同的等长测试方法记录体内等长测量数据，这两种方法在远端固定测试点的胫骨水平上有所不同。方法1在与胫骨隧道成一直线的向量上，于距天然ACL止点外周13 cm处进行远端测试。方法2在髁间窝底部水平的天然ACL止点中心处进行远端测试。所有胫骨隧道的矢状隧道-平台角度和隧道长度均标准化。近端测试点在所有膝关节中均标准化为在解剖学上位于ACL中心起点处或其附近，即在“过顶”位置前方7 mm处。使用这些方法，在每个膝关节中，随着膝关节从70°屈曲到完全伸直以及从70°到140°屈曲，用每种测试方法记录近端和远端测试点之间的长度变化。根据这些数据，计算出从0°到140°屈曲的总偏移量。一个非解剖学远端测试点（方法1）产生的总偏移量为6 mm±1 mm，而同一膝关节中的解剖学测试点（方法2）产生的总偏移量为1 mm±1 mm。根据这些数据，作者得出结论，远端等长测试点的胫骨水平对所得等长测量结果有显著影响，以至于解剖学测试点的等长性最佳。产生非解剖学测试点之间数据的等长仪不应被用于确定ACL重建隧道的位置，也不应被用于推断ACL替代物在不同点固定时所承受的伸长力。相反，本研究的临床意义在于，解剖学移植物位置和解剖学移植物固定位置均很重要，并且在实现这些位置时，术后早期活动范围内移植物伸长应最小，从而带来更稳定的长期结果。
