Fracture Patella

I I Other I I Progression I I Instability I I Patella I I Fracture Other mech. I I Loosening I I Infection... 

Viola R, Vianello R (1999) Three cases of patella fracture in 1,320 anterior cmciate ligament reconstmctions with hone-patellar tendon-bone autograft. Arthroscopy 15 93-97... 

Stein DA et al (2002) The incidence and outcome of patella fractures after anterior cmciate ligament reconstmction. Arthroscopy 18(6) 578-583... 

Miller MD, Nichols T, Butler CA (1999) Patella fracture and proximal patellar tendon mpture following arthroscopic anterior cmciate ligament reconstmction. Arthroscopy 15 640-643... 

Berg EE (1996) Management of patella fractures associated with central third bone-patella tendon-bone autograft ACL reconstructions. Arthroscopy 12(6) 756-759... 

Sleeve avulsion fractures are a particular form of avulsion injury seen in the unossified skeleton which differs from avulsions in adults because the sleeve of periosteum which is pulled off can continue to form bone if not treated. The typical location is at the lower pole of the patella, but the upper pole of the patella, the olecranon and the medial epicondyle can also be affected. Ultrasound demonstrates a sleeve of cartilage that has been avulsed usually with a small fragment of bone (Hunt and Somashekar 2005). In some cases a double cortical sign may be present, indicating elevation of a superficial layer of cortex from the underlying bone. There maybe associated haemarthrosis and patella alta (Fig. 4.14). 

Hsu CC, Tsai WC, Chen CP, Yeh WL, Tang SF, Kuo JK (2005) Ultrasonographic examination of the normal and injured posterior cruciate ligament. J Clin Ultrasound 33 277-282 Hubner U, Schlicht W, Outzen S, Barthel M, Halsband H (2000) Ultrasound in the diagnosis of fractures in children. J Bone Joint Surg Br 82 1170-1173 Hunt DM, Somashekar N (2005) A review of sleeve fractures of the patella in children. Knee 12 3-7 Kannus P (2000) Structure of the tendon connective tissue. 

Patellar fractures can occur from direct and indirect mechanisms, with a direct force being the commonest cause. Potential mechanisms include a powerful quadriceps contraction, a direct anterior blow which may result in an open fracture and patellar dislocation or relocation. It is important to differentiate a fracture from a bipartite patella which has a characteristic location and smooth margins. 

Fig. 14.13. Lateral radiograph showing a transverse fracture through the patella...

Children can also sustain a transverse fracture through the mid-portion of the patella or a stellate pattern fracture. These can occur from falls with the knee in flexion or severe contraction of the quadriceps tendon. These are best seen on the lateral projection. Transverse stress fractures occur due to abnormal quadriceps pull on osteopenic bones in children with cerebral palsy. 

Fractures of the patella also occur in association with femoral shaft, condylar, proximal tibia and posterior dislocation of the hip ( dashboard injury ). 

Fig. 14.14. Lateral radiograph showing a sleeve fracture of the distal pole of the patella (arrow)...

A lateral dislocation causes damage to the medial patello-femoral ligament and vastus medialis obliq-uis. It can also cause an osteochondral fracture from either the lateral femoral condyle which may be sheared of by the patella or alternatively there may be an avulsion of the medial facet of the patella. 

Ditchfield A, Sampson MA, Taylor GR (2000) ultrasound diagnosis of sleeve fracture of the patella. Clin Radiol 55 467-469... 

Nummi J (1971) Fracture of the patella. A clinical study of 707 patellar fractures. Ann Chir Gynaecol Fenn Suppl 179 1-85... 

Rorabeck CH, Bobechko WP (1976) Acute dislocation of the patella with osteochondral fracture a review of 18 cases. J Bone joint Surg 58B 237-240... 

Carter C, Sweetman R (1960) Recurrent dislocation ofthe patella and of the shoulder their association with familial joint laxity. J Bone Joint Surg (Br) 42 721-727 Comhalia A, Arandes JM, Alemany X, Ramon R (1995) Acromioclavicular dislocation with epiphyseal separation of the coracoid process report of a case and review of the literature. J Trauma 38 812-815 Curtis RJ (1990) Operative management of children s fractures of the shoulder region. Orthop Clin North Am 21 315-324... 

SRPL screws (Tampere process) were used in 32 patients to repair small fragment fractures and osteotomies of hand, foot, elbow, and patella. With a follow-up time of up to 37 months, no inflammatory reactions were observed. Biopsies in two patients at 20 and 37 months revealed that no polymeric material remained, that the implant channel had become filled with fibrous connective tissue without evidence of restoration of bony architecture (Pihl make et al., 1992). 

Fig. 14.52a,b. Patella fracture in a patient with persistent anterior knee pain after a traffic accident, a Longitudinal 12-5 MHz US image over the anterior aspect of the patella shows an abrupt discontinuity of the anterior cortical line (arrows) and a marked thickening of the periosteum (arrowheads), b Lateral radiograph confirms a clinically undetected patellar fracture... 

Patellar cartilage abnormalities can occasionally be detected with US on the medial facet of the patella and maybe related to lateral patellar dislocation. US can image an osteochondral fracture as a focal defect of cartilage and irregularity of the hyperechoic line representing the subchondral bone plate (Fig. 14.54). Although US can detect these changes, it should be... 

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