Overstressing patella fractures too soon could hinder the healing process
PTAs face many unique challenges when treating a variety of orthopedic patients. To effectively manage orthopedic injuries, PTAs must be knowledgeable of musculoskeletal tissue healing principles, be familiar with various rehabilitation programs, know how to skillfully apply rehabilitation techniques as well as fundamentally understand common and uncommon soft tissue injuries, fractures and diseases of muscles, bones and joints.Management of patella fractures, both nonoperative and postoperative, provides PTAs with an opportunity to fully utilize each component of effective rehabilitation.
Causes and Types
Fractures of the patella most commonly occur from direct trauma, usually a fall on the knee or a direct blow to the patella. Less frequently, the patella can be fractured by a sudden, violent contraction of the quadriceps.
Patella fractures are classified as either transverse, stellate or vertical. These three categories can be further classified as displaced or nondisplaced. The arterial blood supply to the patella is derived from two systems of vessels from branches of the geniculate arteries. These two systems supply the middle third and apex of the patella. In cases of displaced transverse fractures, the proximal blood supply may be compromised leading to avascular necrosis of the proximal segment.
Overall, the management of patella fractures is based on classification and morphology of the injury. Treatment options range from nonoperative to operative with open reduction and internal fixation to partial or total patellectomy.
Nonoperative care involves the use of extension splinting from four to six weeks. Weight-bearing status is as tolerated. Generally, quad sets and straight leg raises are permitted as soon as pain allows. Usually at around four weeks, active knee flexion can proceed once radiographic confirmation is made of fracture consolidation. The contralateral limb is exercised freely, and a general conditioning program is initiated for upper and lower extremity strengthening. Aerobic fitness is maintained via a single leg stationary cycle ergometer or upper body ergometer (UBE). Care is taken during the maximum protection phase of recovery to guard against passive knee flexion beyond the healing constraints of the fracture.
If quadricep strengthening and knee flexion are progressed too soon, the forces acting across the healing fracture may delay union. Therefore, the PTA must be acutely aware of osseous healing mechanisms and time constraints when overseeing range of motion and strengthening exercises during each phase of recovery from nondisplaced patella fractures. Usually, active range of motion is initiated. Gradual progression to passive range of motion will correlate with solid bone union. Close consultation with the PT is important, since some degree of evaluative skills is necessary for patient progression.
Treatment of patella fractures is based on ranges of acceptable fracture fragment separation exceeding 3 to 4 millimeters. Although patella fracture patterns may vary (Figure 1), stabilization of displaced patella fragments is best accomplished with an open reduction internal fixation procedure. Various techniques are used including tension band wiring, cerclage wiring, lag screws or combinations of the above.
Commonly, tension band and cerclage wiring is used to stabilize displaced transverse patella fractures (Figure 2). The tension band is a dynamic compression device that approximates and compresses the fracture fragments. The additional use of cerclage wiring adds to the stability of the repair and allows early joint motion without redisplacing the fracture fragment. Postoperatively, the involved limb is immobilized in 20 degrees of flexion to support dynamic compression of the tension band wiring procedure.
Postoperative rehabilitation begins approximately one week after surgery. Active knee flexion should be limited to about 100 degrees for at least six weeks following surgery to allow for proper fracture consolidation.
Straight leg raises, submaximal quad isometrics and gentle active short arc knee extension exercises characterize the initial maximum protection phase of recovery. Weight bearing as tolerated with assistive devices is encouraged during the first few weeks following surgery, progressing to full weight bearing by the third or fourth week.
As clearly stated during treatment of nondisplaced patella fractures, care must be taken not to overstress the healing fracture by aggressive flexion, range of motion or resisted knee extension exercises. Radiographic confirmation of fracture consolidation with stable implant fixation and postoperative time greater than six weeks will dictate to the physician and the PT the gradual implementation of the moderate protection phase of recovery.
Active-assisted knee flexion and light resistance quad exercises are begun once the patient is able to demonstrate good quad control, improved knee flexion to 100 degrees, reduced pain and swelling and normalized gait mechanics. Functional closed chain resistance exercises are deferred until the patient is able to demonstrate increased range of motion without signs or symptoms of articular cartilage degeneration. Strength-training exercises of remedial isometrics and progressive concentric and eccentric resistance must approximate and correlate with solid bone union.
Severe comminuted patella fractures are treated surgically with a partial or total patellectomy if significant bone mass cannot be salvaged. However, as little as 25 percent of the patella can be retained with a good outcome when compared to the overall poor results of total patellectomy.
Several complications have been identified following patella fractures. Breakage of wires, loss of fixation, re-fracture, delayed and malunion, loss of knee motion and osteoarthritis are complications that must be immediately identified and properly cared for. Although generally rare, any one of these complications can significantly alter the desired functional recovery following patella fractures.
The PTA must understand fracture injury and repair mechanisms, various surgical techniques and progressive rehabilitation interventions which closely parallel fracture healing constraints in order to effectively assist the PT in managing nonoperative and postsurgical patella fractures.
This article was adapted, and the drawings reproduced with permission from the publishers of the text Fundamental Orthopedic Management for the Physical Therapist Assistant by Gary Shankman, (1997) St. Louis: Mosby Year Book, Inc.