Lowery Kathryn, Dearden Paul, Sherman Kevin, Mahadevan Vishy, Sharma Hemant
Hull Royal Infirmary.
Royal College of Surgeons.
Injury. 2015;46(6):970-4. doi: 10.1016/j.injury.2015.03.017. Epub 2015 Mar 16.
Septic arthritis following intra-capsular penetration of the knee by external fixation devices is a complication of traction/fixation devices inserted in the lower extremity [1,2]. The authors were unable to find reference to or exact measurements of the capsular attachments relating to the distal femur documented in the current literature. This study aimed to demonstrate the capsular attachments and reflections of the distal femur to determine safe placements of wires or traction devices.
The attachments of the capsule to the distal femur were measured in 10 unembalmed cadaveric knees. Capsular attachments were measured anteriorly at the maximal extension of the supra-patella pouch. Medially and laterally measurements were expressed as percentages related to the maximal AP diameter of the distal femur.
Mean distance from the centre of the anterior part of the notch to the superior fold was 79.5mm (Range 48.1-120.7 mm). The medial capsular reflections measured in a plane from the adductor tubercle to the anterior edge of the medial femoral condyle demonstrated the capsular reflection was attached an average of 57% back from the anterior edge (Range 41-74%). Laterally the capsular reflections on a line drawn from the maximal diameter in the sagittal plane were attached an average of 48% from the anterior reference point (Range 33-57%). Measuring the reflections at 45 degrees to the long axis of the femur in the sagittal plane the attachment was an average of 51% from the anterior reference point.
Capsular reflections varied among specimens. Medially the capsule attachment was up to 74% of diameter of distal femur at the level of the adductor tubercle. Therefore, the insertion of distal femoral traction pins or similar should be placed proximal to the adductor tubercle and no further than 25% of the distance to the anterior cortex. Care is also needed to ensure pins do not travel to exit too anteriorly on the lateral side as capsular attachments were found to be up to a distance 48% of the diameter of the femur from anterior reference point. Distal condylar extra-articular fixation with Schanz screws is feasible if orientated in the oblique plane.
外固定装置穿入膝关节囊内后引发的化脓性关节炎是下肢牵引/固定装置的一种并发症[1,2]。作者在当前文献中未能找到与股骨远端相关的关节囊附着点的参考文献或确切测量数据。本研究旨在展示股骨远端的关节囊附着点及反折情况，以确定钢丝或牵引装置的安全放置位置。
在10具未防腐处理的尸体膝关节上测量关节囊与股骨远端的附着情况。在髌上囊最大伸展时，于前方测量关节囊附着点。在内侧和外侧的测量值表示为与股骨远端最大前后径相关的百分比。
从切迹前部中心到上皱襞的平均距离为79.5毫米（范围48.1 - 120.7毫米）。在内侧，从内收肌结节到股骨内侧髁前缘的平面上测量关节囊反折情况，结果显示关节囊反折平均附着于距前缘向后57%处（范围41 - 74%）。在外侧，在矢状面最大直径所画直线上的关节囊反折平均附着于距前参考点48%处（范围33 - 57%）。在矢状面与股骨长轴成45度角测量反折情况时，附着点平均距前参考点51%。
不同标本的关节囊反折情况各异。在内侧，在内收肌结节水平，关节囊附着点可达股骨远端直径的74%。因此，股骨远端牵引针或类似装置的插入应置于内收肌结节近端，且距离前皮质不超过25%。还需注意确保针在外侧不会过于靠前穿出，因为发现关节囊附着点距前参考点可达股骨直径的48%。使用斯氏针进行远端髁关节外固定时，若在斜平面定向则是可行的。
