1、原则

The patella is the largest sesamoid bone in the human body. It is located within the extensor apparatus of the knee. Anatomical features include the proximal articular body, with an extraarticular anterior surface and a posterior articular surface, and the extraarticular distal pole. The rectus femoris and vastus intermedius muscles insert at the superior pole of the body and the vastus medialis and vastus lateralis muscles on either side. The patellar tendon originates from the inferior pole and inserts into the tibial tuberosity. The articular surface has the thickest layer of cartilage in the body, up to 5 mm, reflecting the very high resultant loads across the patello-femoral joint, rendering it susceptible to chondromalacia and degenerative joint disease.

手术解剖

髌骨是人体最大的籽骨，其位于膝关节伸膝装置的里面，解剖特征包括其正好位于关节的中部，有一个关节外面、一个关节内面和一个关节外下极。股直肌和股中间肌的止点经过髌骨的上表面；股内侧肌和股外侧肌经过其两侧。髌韧带起自髌骨下极止于胫骨结节。髌骨的内关节面有人体最厚的软骨层约有5mm，反映出髌股关节承受非常高的负荷，这正是容易发生髌骨软化及关节退变的原因。

History and examination  历史和检查

Patellar fractures comprise about 1% of all fractures and are mostly caused by direct trauma to the front of the knee, for example, a direct fall, or a blow onto the flexed knee.

髌骨骨折占全身骨折的1%，大部分由膝关节前方的直接暴力引起，例如，摔倒或打击在弯曲的膝部。

Bony avulsions of the adjacent tendons, or pure ruptures of the quadriceps and patellar tendons, are caused by indirect forces.

肌腱的撕脱骨折，或纯粹的股四头肌肌腱断裂和髌腱断裂，多由间接暴力引起。

Typical signs are swelling, tenderness and limited, or lost, function of the extensor mechanism.

骨折的典型征象是肿胀，压痛或活动受限，或有伸膝功能障碍。

Preservation of active knee extension does not rule out a patellar fracture if the auxiliary extensors of the knee - the medial and lateral parapatellar retinacula - are intact.

伸膝功能正常不能除外髌骨骨折，因为膝关节的附属韧带--内、外侧副韧带完整就可以伸膝。

If displacement is significant, it is possible to palpate a defect between the fragments, if present. The hemarthrosis is usually obvious. The examination must include assessment of the soft tissues, so as not to confuse with an injury to the prepatellar bursa, or to omit grading the injury if the fracture is open.

如果移位明显，可以触诊到畸形（两骨折块中见空虚）。关节积血通常明显。检查必须包括软组织条件评估，以便不混淆髌前囊损伤或忽略开放伤严重程度。

In addition to the standard x-rays of the knee in two planes, a tangential (“skyline”) view of the patella is useful. In the AP view, the patella normally projects into the midline of the femoral sulcus. Its lower pole is located just above a line drawn across the distal profile of the femoral condyles. In the lateral view the proximal tibia must be visible to exclude a bone avulsion of the patellar tendon from the tibial tuberosity. A rupture of the patellar tendon, or an abnormal position of the patella like patella alta (high-riding patella), or patella baja (shortening of the tendon), can be recognized with the help of the Insall-Salvati method. This is the relationship between the length of the patella (B) and of the patellar tendon (A) on the lateral x-ray, r=B/A. This ratio is normally r = 1. A ratio r < 0.8 suggests a high-riding patella (patella alta), or patellar tendon rupture.

除了标准膝关节正侧位，髌骨的切线位也很有帮助。正位象，髌骨正常投影在股骨间沟中间。它最低点位于股骨内外髁连线的上方。侧位象，胫骨近端必须除外髌韧带从胫骨结节的撕脱骨折块。髌韧带断裂或髌骨位置改变（如高位髌骨）或缩短肌腱，可以用Insall-Salvati 方法确定。上图就是髌骨长度与髌腱长度侧位X线比，此比值正常情况为1。如果比值＜0.8提示高位髌骨或髌腱断裂。

The third important x-ray projection is the 30? tangential view, which is obtainable in 45° knee flexion. If a longitudinal, or osteochondral fracture, is suspected, the 30? tangential view is a helpful diagnostic adjunct.

第3种重要的X线检查是在膝关节屈曲45°时髌骨切线位30°象，如果有纵行骨折或软骨骨折，则切线位是一个很有诊断价值的方法

Special imaging is helpful in certain cases, such as stress fractures, in elderly patients with osteopenia and hemarthrosis, and also in cases of patellar nonunion, or malunion.

特殊的影像在特殊的病例中是很有帮助的，例如，老年骨质疏松病人伴有关节积血的应力骨折，或髌骨骨折不愈合和骨不连。

Computed tomography is recommended only for the evaluation of articular incongruity in cases of nonunion, malunion and patello-femoral alignment disorders.

CT被推荐应用于评估关节内骨折不愈合、骨不连和髌股关系紊乱证。

Scintigraphic examination (or MRI) can be helpful in the diagnosis of stress fractures; a leukocyte scan can reveal signs of osteomyelitis.

MRI在诊断应力骨折有价值的；白细胞扫描显示骨髓炎的征象。

MRI can be helpful to diagnose cartilage defects and lesions.

 MRI在诊断软骨损伤方面很有价值。

Tendon ruptures and patellar dislocation must be ruled out. Isolated rupture of the quadriceps, or patellar, tendon must be excluded by clinical evaluation (palpation) and ultrasound scan (or MRI). Dislocation, most commonly occurring to the lateral side, may result in osteochondral shear fractures with lesions of the medial margin of the patella, and occasionally impaction fractures of the lateral lip of the patellar groove of the femur.

X-ray by courtesy of Spital Davos, Switzerland, Dr C Ryf and Dr A Leumann.

肌腱断裂和髌骨脱位必须除外，孤立的股四头肌肌腱断裂或髌腱断裂，必须从临床触诊或超声或MRI除外。脱位，多发生在外侧，可导致内侧髌骨骨软骨断裂损伤，偶尔髌骨撞击股骨引起股骨外侧缘骨折（上图）。（上图为瑞士Dr C Ryf 提供）

2、复位与固定

The knee joint and fracture lines must be irrigated and cleared of blood clots and small debris to allow exact reconstruction.

An image intensifier should always be available so that the final result can be checked in the AP and lateral planes.

膝关节和骨折线必须冲洗并清除血块，小碎片要求准确复位，术中即时透视重要的，最后结果通过正侧位X线片确定。

Occasionally, the patellar tendon is avulsed from the lower pole of the patella, together with a thin shell, or “sleeve”, of bone as illustrated.

有时，髌腱从髌骨下极撕脱，骨如图所示。

This may be very subtle on x-rays as the sleeve remaining within the avulsed tendon is thin and is often not apparent on over-penetrated images, whilst at the same time, the lower pole of the patella may have a virtually normal profile. A clue may be found by detection of a patella alta (as appreciated by the Insall-Salvati index).

 这种损伤可能很细微，在X线上当撕脱骨折仍然被肌腱包裹并很微小，通常在X线上不是很明显的。有时，髌骨下极可能有一个看起来正常的轮廓，有一个线索可以发现这种损伤，如Insall-Salvati比值。

Insert a partially threaded cannulated screw, with a washer, as a lag screw.

 用半螺纹螺钉加个垫圈作为拉力螺钉从下部拧入。

As implant pull-out, or failure, is virtually inevitable, the bending distraction forces must be neutralized by additional patellotibial cerclage wiring.

为防止拔出，或失败的发生。弯曲力必须被中和靠一个外加的髌骨环扎术。

Repair any tears of the lateral and medial patellar retinacula with sutures.

修复缝合受损的内外侧韧带。