Review Article Patellar Fractures in Adults

Abstract J. Stuart Melvin, MD Patellar fracture is a common injury caused by excessive tension Samir Mehta, MD through the extensor mechanism or a direct blow. The intact increases the leverage and efficiency of the extensor mechanism and articulates with the femoral trochlea. Patellar fractures can lead to stiffness, extension weakness, and patellofemoral arthritis. Nonsurgical management is indicated for nondisplaced fractures with an intact extensor mechanism. Surgical fixation is recommended for fractures that either disrupt the extensor mechanism or demonstrate >2 to 3 mm step-off and >1 to 4 mm of displacement. Anatomic reduction and fixation with a tension-band technique is associated with the best outcomes; however, symptomatic hardware is a frequent complication. Open fractures are associated with more complications than closed fractures. These complications can be mitigated with timely débridement, irrigation, and internal fixation.

atellar fractures account for ap- along the margins of the patella to Pproximately 1% of all fractures.1 form the patellar retinaculum, which Historically, treatment methods aids in extension. changed as fixation strategies were Its subcutaneous position makes debated. More recently, the vital role the patella prone to From the Department of of the patella in maximizing extensor and injury from direct blows. Poste- Orthopaedic Surgery, University of mechanism efficiency has become riorly, the superior three fourths of Pennsylvania, Philadelphia, PA. clear, and treatment methods di- the patella is covered with the thick- Dr. Mehta or an immediate family rected at preservation have led to im- est articular cartilage in the body. member is a member of a speakers’ bureau or has made paid proved outcomes. However, manage- The posterior articular surface is presentations on behalf of AO and ment of patellar fracture remains composed of two large facets—me- Smith & Nephew and has received challenging because of the subcuta- dial and lateral—separated by a ver- nonincome support (such as tical ridge1 (Figure 1). equipment or services), neous and intra-articular location of commercially derived honoraria, or the patella as well as the desire for The patella typically forms from a other non-research–related funding early active knee motion. single ossific nucleus. However, in (such as paid travel) from Wolters 2% to 3% of the population, a sec- Kluwer Health—Lippincott Williams ondary ossific nucleus fails to unite & Wilkins. Neither Dr. Melvin nor any immediate family member has Anatomy with the primary nucleus, resulting received anything of value from or in a bipartite patella.2 Bipartite pa- owns stock in a commercial The patella is the largest sesamoid tella is bilateral in 50% of patients company or institution related in the body. The quadriceps directly or indirectly to the subject of and occurs most frequently at the su- 2 this article. tendon and the fascia lata blend to perolateral edge. Bipartite patella the anterosuperior margin of the pa- should not be confused with fracture J Am Acad Orthop Surg 2011;19: 198-207 tella. The patellar tendon originates (Figure 2). on the inferior border. Portions of The patella receives its blood sup- Copyright 2011 by the American Academy of Orthopaedic Surgeons. the fascia lata, vastus medialis, and ply from an anastomotic ring that vastus lateralis aponeurosis pass originates from the geniculate arter-

198 Journal of the American Academy of Orthopaedic Surgeons J. Stuart Melvin, MD, and Samir Mehta, MD

3 ies. The superior portion of the ring Figure 1 Figure 2 lies anterior to the quadriceps ten- don, and the inferior portion passes posterior to the patellar tendon. Ves- sels from the ring penetrate the mid- dle of the anterior patella and the in- ferior pole along the infrapatellar fat pad. Although the incidence of os- teonecrosis secondary to fracture has been reported to be as high as 25%, clinical outcomes were not affected.3 Circumferential dissection or exces- Articular facets of the patella. The sive stripping of the anterior surface arrows indicate the location of the should be avoided given the centripe- transverse ridges. (Reproduced tal blood supply. with permission from Harris RM: Fractures of the patella and injuries to the extensor mechanism, in AP radiograph demonstrating Bucholz RW, Heckman JD, Court- bipartite patella. (Reproduced from Patellar Biomechanics Brown CC, eds: Rockwood and Atesok K, Doral MN, Lowe J, Green’s Fractures in Adults,ed6. Finsterbush A: Symptomatic The knee extensor mechanism gener- Philadelphia, PA, Lippincott bipartite patella: Treatment ates torque and keeps the body up- Williams & Wilkins, 2006, vol 2, p alternatives. J Am Acad Orthop right against gravity. The patella acts 1975.) Surg 2008;16:455-461.) as a pulley, shifting the pull of the quadriceps anteriorly, thereby in- Figure 3 creasing the moment of the quadriceps by up to 30%.4 Loading patterns about the patella are complex. The quadriceps loads the patella in tension (Figure 3, A). Knee flexion results in compressive forces along the posterior patella. Three-point bending stresses are cre- ated within the patella during flexion (Figure 3, B). Maximal tensile forces through the quadriceps and patellar tendons have been recorded to be as high as 3,200 N and 2,800 N, respectively.5 Activi- ties such as stair climbing and squat- ting may generate patellofemoral compressive forces greater than seven times body weight and anterior A, The patella is loaded primarily in tension with the knee in full extension. B, During flexion, the patella experiences a combination of tension, patellar surface strains close to val- compression and three-point bending forces (arrows). (Reproduced with ues that result in fracture.5,6 permission from Carpenter JE, Kasman R, Matthews LS: Fractures of the patella. J Bone Joint Surg Am 1993;75:1550-1561.)

Mechanism of Injury which often results from a fall or placed, with the extensor mechanism Patellar fracture may occur as a re- dashboard injury.6 This mechanism remaining intact, significant chon- sult of direct or indirect forces. The causes the patella to fail in compres- dral damage may occur.1 type of force determines the fracture sion, resulting in a comminuted or More commonly, the patella fails pattern. A direct force consists of a stellate fracture pattern. Although in tension as indirect force from the direct blow to the anterior knee, >50% of these fractures are nondis- extensor mechanism exceeds the

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Figure 4

Descriptive classification of patellar fractures. A, Nondisplaced. B, Transverse. C, Lower or upper pole. D, Multi- fragmented nondisplaced. E, Multifragmented displaced. F, Vertical. G, Osteochondral. (Adapted with permission from Harris RM: Fractures of the patella and injuries to the extensor mechanism, in Bucholz RW, Heckman JD, Court-Brown CC, eds: Rockwood and Green’s Fractures in Adults, ed 6. Philadelphia, PA, Lippincott Williams & Wilkins, 2006, vol 2, p 1974.)

strength of the bone.6 Typically, this defect. The continuity of the exten- formation regarding the mechanism fracture type is caused with rapid sor mechanism may be evaluated of injury but does not direct treat- knee flexion against a fully con- with a straight leg raise examination. ment1,6 (Figure 4). The Orthopaedic tracted quadriceps muscle, resulting When the test is limited by pain, as- Trauma Association classification is in transverse fracture or avulsion of piration of the and in- based on degree of articular involve- the inferior pole. The force often jection of local anesthetic may allow ment and number of fracture frag- continues beyond the patella, ex- the patient to attempt this maneuver. ments; however, the clinical utility of tending in a transverse fashion this system is uncertain.8 through the retinaculum and causing fracture displacement and loss of ac- Radiographic Evaluation tive knee extension.6 Management Standard AP and lateral radiographs of the knee should be obtained. Be- The goals of management include re- Clinical Presentation and cause of superimposition of the pa- storing the extensor mechanism Assessment tella on the femoral condyles, the AP while maximizing articular congru- view may be difficult to interpret. ency. Every effort should be made to Evaluation of a patient with knee Lateral radiographs are useful in as- preserve as much patellar bone as pain begins with a detailed history sessing displacement and articular possible. and physical examination. History of congruity in patients with transverse a direct blow to the knee or eccentric fracture. Axial views are of limited Nonsurgical loading should raise suspicion for use except with vertical fracture pat- patellar fracture or other extensor Nonsurgical management is indi- terns. Advanced imaging techniques mechanism injury. Associated inju- cated for fractures with a clinically such as arthrography, CT, MRI, and ries, such as femoral neck fracture, intact extensor mechanism and mini- bone scans are rarely indicated for posterior wall acetabular fracture, mal step-off and/or fracture displace- isolated acute patellar fractures. and knee dislocation, should be ment (<2 to 3 mm and <1 to 4 mm, sought for high-energy dashboard respectively).1,6 Successful results mechanisms. Classification have been reported with two differ- The begins with ent treatment regimens. inspection of the soft-tissue envelope. Patellar fractures may be classified as Braun et al9 retrospectively re- Suspected open fractures are best displaced (ie, step-off >2 to 3 mm viewed 40 nonsurgically managed evaluated with a saline load test per- and fracture gap >1 to 4 mm) or fractures with an intact extensor formed with intra-articular injection nondisplaced.6 Classification often mechanism and <1 mm of fracture of 150 mL of sterile saline.7 In closed predicts treatment. However, more displacement. Fractures were man- patellar fractures, further inspection commonly, patellar fractures are aged with a long leg splint for a few and palpation reveal hemarthrosis, classified descriptively according to days followed by partial weight bear- pain with palpation, and a palpable fracture pattern, which may offer in- ing and physiotherapy. At an average

200 Journal of the American Academy of Orthopaedic Surgeons J. Stuart Melvin, MD, and Samir Mehta, MD follow-up of 30.5 months, 80% of loose bodies and osteochondral frac- and comminuted patellar fractures. patients were pain free, and 90% ture. Many tension-band techniques had full range of motion (ROM). In have undergone biomechanical test- a large series, Boström1 used plaster Open Reduction ing. In a cadaver model, Weber 14 immobilization for a mean duration and et al demonstrated that Magnusson of 4 weeks to manage patellar frac- Open reduction and internal fixation wiring (Figure 5, D) and MATB tures with an intact extensor mech- is the preferred treatment for most wiring permitted less separation of displaced patellar fractures. Al- anism, <3 mm of articular step-off, fracture fragments than either cir- though the techniques and materials and <4 mm of fracture widening. cumferential wiring or standard used in patellar fixation have Good or excellent outcomes were re- tension-band wiring. Additionally, changed substantially, the goals of they found that repair of the retinac- ported in 99% of fractures at a mean restoration of normal anatomy and ular defect contributed to the overall 9-year follow-up (210/212). extensor function remain con- stability of the construct. Fortis These reports suggest that good to stant.1,11 et al15 demonstrated increased com- excellent results can be expected for Several incisions may be used to ex- pressive strain in a transverse frac- minimally displaced fractures with pose the patella; however, a longitudi- ture model with the addition of a an intact extensor mechanism. We nal midline extensile incision centered cerclage wire (Figure 5, E) to the typically recommend early weight over the patella is preferred. For trans- MATB construct. In a cadaver bearing with a hinged knee brace verse fractures, full-thickness medial model, Benjamin et al16 showed that locked in extension. Isometric quad- and lateral flaps allow access to reti- screw fixation alone (Figure 5, F) riceps exercise and straight leg raises nacular tears while enabling palpation was adequate for transverse fractures are begun when pain has subsided. to confirm reduction of the joint sur- with good bone stock; however, the Active and active-assisted ROM is face. Gardner et al12 advocated lat- MATB performed better for fractures begun at 1 to 2 weeks, and resistance eral parapatellar arthrotomy with in- with comminution or osteopenia. exercises are added at 6 weeks. One ternal rotation of the patella to 90° Simple wiring techniques, such as the week after motion is allowed, radio- for direct visual reduction of commi- Magnusson and Lotke longitudinal graphs are obtained to evaluate for nuted fractures. In general, trans- anterior band (Figure 5, G) tech- displacement. verse incisions should be avoided be- niques, may not allow sufficient fixa- Nonsurgical management should cause they compromise approaches tion for early activity.11 be considered for displaced patellar for future knee procedures. The figure-of-8 wire pattern plus fractures in the patient with signifi- Historically, tension-band wiring tensioning has been investigated, as cant medical comorbidities. Pritch- has been the most commonly used well. In testing on wooden , 17 ett10 reported a series of 18 patellar technique for the management of pa- John et al found that incorporating fractures with >1 cm of displacement tellar fracture. This technique con- a horizontal figure-of-8 pattern with managed with a Velcro closure verts the anterior tension forces pro- four strands crossing the fracture site splint, early full weight bearing, and duced by the extensor mechanism and tensioning the wire with two and knee flexion into compression straight leg raises. Of the 12 patients twists at the corners of the tension forces at the articular surface. Nu- band improved interfragmentary available at 2-year follow-up, only 3 merous tension-band wiring tech- compression by 63% compared with considered their outcome to be poor. niques have been described (Figure a vertically oriented MATB with a No patient had severe pain, but all 5). Early techniques, such as the single tensioning twist (Figure 5, H). patients had extensor lag of ≥20°. standard tension band (Figure 5, A) Screws offer better biomechanical and the modified anterior tension performance than do longitudinal Surgical band (MATB) (Figure 5, B), were K-wires in the MATB construct. An incompetent extensor mechanism further modified to create an MATB Screws provide greater rigidity than is the most common indication for technique involving longitudinal do K-wires and provide resistance surgery. In some cases, despite active Kirschner wires (K-wires) and 18- against tensile loading with the knee knee extension, fracture separation gauge stainless steel wire in a figure- in full extension. In a cadaver model, >1 to 4 mm or step-off >2 to 3 mm of-8 pattern looped over the anterior Burvant et al18 found that the MATB may be relative indications for surgi- patella13 (Figure 5, C). Currently, this technique with cancellous screws cal management. Additional surgical construct is the most widely accepted performed better than the MATB indications include intra-articular method of fixation for transverse technique with K-wires. However, in

April 2011, Vol 19, No 4 201 Patellar Fractures in Adults

Figure 5

Illustrations of patellar fixation techniques. A, Standard tension band. B, Modified anterior tension band (MATB). C, MATB with vertical figure-of-8 wire. D, Magnusson wiring. E, Cerclage wiring. F, Parallel cancellous lag screws. G, Lotke longitudinal anterior band. H, MATB with horizontal figure-of-8 wire. I, Figure-of-8 tension band through cannulated screws. J, Pyrford technique. K, Separate vertical wiring (lateral view). L, Basket plate. (Panels A, B, D, and E reproduced with permission from Weber MJ, Janecki CJ, McLeod P, Nelson CL, Thompson JA: Efficacy of various forms of fixation of transverse fractures of the patella. J Bone Joint Surg Am 1980;62:215-220. Panels C, F, and I reproduced with permission from Carpenter JE, Kasman RA, Patel N, Lee ML, Goldstein SA: Biomechanical evaluation of current patella fracture fixation techniques. J Orthop Trauma 1997;11:351-356. Panel G reproduced with permission from Hughes SC, Stott PM, Hearnden AJ, Ripley LG: A new and effective tension-band braided polyester suture technique for transverse patellar fracture fixation. Injury 2007;38:212-222. Panel H reproduced with permission from John J, Wagner WW, Kuiper JH: Tension-band wiring of transverse fractures of patella: The effect of site of wire twists and orientation of stainless steel wire loop. A biomechanical investigation. Int Orthop 2007;31:703-707. Panel J reproduced with permission from Chatakondu SC, Abhaykumar S, Elliott DS: The use of non-absorbable suture in the fixation of patellar fractures: A preliminary report. Injury 1998;29:23-27. Panel K reproduced with permission from Yang KH, Byun YS: Separate vertical wiring for the fixation of comminuted fractures of the inferior pole of the patella. J Bone Joint Surg Br 2003;85:1155-1160. Panel L reproduced with permission from Kastelec M, Veselko M: Inferior patellar pole avulsion fractures: Osteosynthesis compared with pole resection. J Bone Joint Surg Am 2004;86:696-701.)

the clinical setting, it is often difficult Alternative Tension-band studied in biomechanical testing and to place the tension-band wires Materials clinical series. around the tips and heads of screws. Traditionally, MATB fixation has in- McGreal et al21 compared MATB A revised method in which a figure- corporated stainless steel wire fash- with braided polyester suture (No. 5 of-8 tension-band wire is passed ioned in a figure-of-8 configuration Ti-cron [Covidien, North Haven, through parallel cannulated screws with two strands crossing the frac- CT]) with 18-gauge stainless steel was devised to avoid this difficulty ture. However, because of the diffi- wire in a cadaver model. Although (Figure 5, I). In a cadaver fracture culty in manipulating stainless steel braided polyester suture was found model, Carpenter et al19 found that wire and because of high reoperation to have 75% the tensile strength of tension-band wiring through parallel rates secondary to painful hardware 18-gauge stainless steel wire, it per- 4.0-mm cannulated lag screws pro- or wire migration, techniques em- formed as well as wire over 2,000 vided optimal stability. Berg20 treated ploying alternatives to wire have knee cycles. Patel et al22 evaluated 10 patients with this construct and been investigated. Braided polyester the MATB and Lotke longitudinal reported clinical union in all pa- suture is the most extensively re- anterior band techniques with either tients, including three revisions. searched alternative. It has been braided polyester suture (No. 5 Ethi-

202 Journal of the American Academy of Orthopaedic Surgeons J. Stuart Melvin, MD, and Samir Mehta, MD bond [Ethicon, Somerville, NJ]) or compared with open surgery. Several tellofemoral contact patterns and 1.25-mm stainless steel wire to man- authors have reported favorable re- stresses. They found that patellofem- age transverse patellar fracture in 10 sults with arthroscopic reduction oral contact stress increased as the cadaver . No fixation failures and various percutaneously placed size of the discarded portion of the were noted. screw-and-wire constructs in the patella increased. Additionally, in Two series reported the outcomes management of noncomminuted pa- contrast to the technique used by 30 32 of patellar fractures managed with tellar fractures.26,27 Successful out- Saltzman et al, Marder et al found tension-band techniques fastened comes also have been reported fol- that reattachment of the patellar ten- with braided polyester suture. Chat- lowing application of a circular don to the anterior surface of the re- 23 akondu et al managed transverse external fixator with arthroscopic re- maining patella—which most closely patellar fractures in seven patients duction in the management of com- resembles native anatomy— substan- with the Pyrford tension band tech- minuted patellar fractures.28 Al- tially minimized contact stresses. nique (Figure 5, J) using braided though these small studies appear Partial patellectomy is most polyester suture (No. 5 Ti-cron). At promising, the methods described strongly indicated for comminuted 6-week follow-up, all fractures had have not gained widespread accep- fractures of the inferior patellar pole. united, and pain-free knee function tance. The authors of these articles Some fractures involving the inferior was achieved. Two patients required stress careful selection of patients pole are effectively managed like pa- outpatient suture removal for knot suitable for these techniques and ac- tellar tendon avulsions, with frag- 24 symptoms. Gosal et al compared knowledge the inability to address ment excision and tendon reattach- 21 patellar fractures managed with tears of the retinaculum. ment via suture and transosseous MATB with stainless steel wire to 16 tunnels or suture anchors (Figure 6). cases managed with two braided Partial Patellectomy and Inferior Cerclage reinforcement of the repair polyester sutures (No. 5 Ethibond). Pole Fracture with a heavy suture or wire passed At a mean follow-up of 30 months, Partial patellectomy was developed through the quadriceps tendon and a reoperation was required in eight pa- as an alternative to total patellec- tibial tubercle bone tunnel has also tients treated with wire compared tomy, and partial patellectomy has been described.33 with 1 patient treated with suture. been described in the management of Newer methods of fracture fixa- Polyester suture compared favorably various fracture patterns. Retention tion have been described in an effort with stainless steel wire. of a portion of the patella is thought to preserve patellar bone and allow Based on the available literature, to preserve some of the patellar mo- for early ROM. Yang and Byun34 our preferred method of fixation for ment arm and improve strength.4,29 described the technique of separate mid patella transverse fracture is to Saltzman et al30 reported the re- vertical wiring in 25 patients and use figure-of-8 tension-band wiring sults of 40 patients with displaced reported a 100% union rate and with stainless steel wire passed transverse or comminuted fractures no wire breakage at an average through parallel cannulated screws, managed with partial patellectomy follow-up of 22 months (Figure 5, as described by Carpenter et al19 and and reapproximation of the patellar K). The basket plate technique has Berg.20 For comminuted fracture, we or quadriceps tendon to the articular been investigated in two clinical se- use interfragmentary screws and/or edge of the remaining patella. At an ries35,36 (Figure 5, L). This plate con- cerclage wiring to supplement can- average 8.4-year follow-up, good or forms to the shape of the inferior pa- nulated screw tension banding. excellent results were reported in tellar pole and is secured to the 78% of patients, and mean quadri- patellar body with superiorly di- Minimally Invasive Techniques ceps strength was found to be 85% rected screws. The incidence of soft-tissue injury in that of the contralateral extremity. conjunction with patellar fracture The authors concluded that partial Total Patellectomy has led to the study of less invasive patellectomy is effective in the man- As our knowledge of knee biome- management techniques. Luna- agement of select patellar fractures. chanics and internal fixation has im- Pizzaro et al25 used to Böstman et al31 reported poor out- proved, the indications for total pa- confirm reduction and a percutane- comes with removal of >40% of the tellectomy have diminished. Total ous osteosynthesis device to place an patella. In a cadaver study published patellectomy may result in a >49% MATB. Percutaneous fixation re- in 1993, Marder et al32 evaluated the reduction in quadriceps strength.6,29 sulted in reduced surgical time, less effect of patellectomy size and the lo- Few excellent clinical outcomes have pain, and higher functional scores cation of tendon reattachment on pa- been observed with total patellec-

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1,6 tomy. Thus, every attempt should Figure 6 be made to retain all or part of the patella. Total patellectomy may be indicated in rare cases of failed inter- nal fixation, infection, tumor, or patellofemoral arthritis. When total patellectomy is performed, consider- ation should be given to advancing the vastus medialis obliquus muscle over a longitudinally closed defect. Strength and outcomes are better with this technique than with stan- dard total patellectomy37 (Figure 7).

Open Patellar Fracture Six percent to 9% of patellar frac- tures are open.1,38,39 More than 90% of these injuries occur as a result of mo- tor vehicle collisions, with nearly 70% accompanied by other injuries.38-40 In contrast, closed patellar fractures oc- cur most commonly secondary to falls, are more often isolated, and are less likely to be comminuted or to re- sult in infection. Data on the management and out- comes of open patellar fractures are limited to a few clinical series and case-control studies. Despite the high-energy nature of these injuries, A, Illustrations demonstrating partial patellectomy with tendon advancement satisfactory outcomes have been re- through bone tunnels. B, Lateral view with tendon advancement to the anterior patella, which more closely restores anatomy. C, Lateral view with ported. tendon advancement to the articular surface, which causes patellar rotation. 40 Catalano et al reported on a se- The arrow indicates rotation. (Panel A adapted with permission from Azar F: ries of 76 patients with 79 open pa- Traumatic disorders, in Canale ST: Campbell’s Operative Orthopaedics,ed tellar fractures (12 Gustilo and An- 10. Philadelphia, PA, Mosby, 2003, vol 3, p 2470. Panels B and C reproduced with permission from Marder RA, Swanson TV, Sharkey NA, derson type I, 42 type II, 25 type III). Duwelius PJ: Effects of partial patellectomy and reattachment of the patellar Seventy-seven fractures were man- tendon on patellofemoral contact area and pressures. J Bone Joint Surg Am aged with immediate irrigation and 1993;75:35-45.) débridement followed by definitive fixation and antibiotics. Despite a high percentage of secondary proce- formed in half the cases, and the re- with primary fracture fixation and dures (65%), good to excellent mainder were managed with patel- wound closure. ROM (mean, 112°) and outcomes lectomy or partial patellectomy. Anand et al39 recently presented a were attained. According to the Böstman grading case-control study comparing the re- Torchia and Lewallen38 presented a scale, 77% achieved good or excel- sults of 16 open patellar fractures series of 47 open patellar fractures in lent results. Deep infection occurred with matched closed patellar frac- 44 patients with a mean follow-up of in six cases, all of which had exces- tures at a mean follow-up of 45 9.4 years. Soft-tissue injury was clas- sive delays in wound closure or cov- months. Patients with open patellar sified according to the system of erage. Nonunion occurred in two fractures had higher injury severity Gustilo and Anderson in 55 patients cases in which nonrigid fixation was scores and a greater number of asso- (8 type I, 42 type II, 1 type IIIA, 4 used. No infections or nonunions ciated injuries (mean, 22.75 versus type IIIB). Osteosynthesis was per- were reported for the cases managed 7.06; and mean, 13 versus 5, respec-

204 Journal of the American Academy of Orthopaedic Surgeons J. Stuart Melvin, MD, and Samir Mehta, MD

Figure 7 for 4 weeks. After 4 weeks, ROM is progressed. In the setting of tenuous fixation, partial patellectomy, or a noncompliant patient, full weight bearing in a cylinder cast in exten- sion for 6 weeks is instituted before progressing to a hinged knee brace. Isometric quadriceps exercises and straight leg raises are encouraged as soon as pain subsides. ROM may be delayed in the setting of tenuous soft-tissue envelope, wound closure, or fracture fixation.

Complications

Symptomatic hardware is among the most frequently encountered compli- cations. Overall symptomatic hard- ware rates from zero to 60% have been reported, often requiring hard- ware removal; however, rates vary widely and have been inconsistently Illustrations demonstrating the anterior (A) and medial (B) view of total reported with regard to specific fixa- patellectomy with advancement of the vastus medialis obliquus muscle over tion techniques.6,11,20,23-25,38,41 Symp- a longitudinally closed defect. (Redrawn with permission from Günal I, Taymaz A, Köse N, Göktürk E, Seber S: Patellectomy with vastus medialis tomatic hardware appears to be obliquus advancement for comminuted patellar fractures: A prospective more common in open fractures, randomised trial. J Bone Joint Surg Br 1997;79:13-16.) possibly because of increased dam- age to the soft-tissue envelope.38,39 Hardware failure is rare. Smith tively). Although there were trends et al42 reported catastrophic hard- toward more pain and complications Postoperative ware failure resulting in loss of re- as well as lower functional scores in Management and duction in 8% of cases managed the open fracture group, these differ- Rehabilitation with MATB. Wire migration into the ences did not reach statistical signifi- popliteal fossa and the right ventricle No data exist on outcomes for spe- cance. has also been reported secondary to cific postoperative protocols, but 43,44 We recommend urgent débride- late hardware failure. several clinical protocols have been ment, irrigation, and definitive fixa- Knee stiffness is a known compli- tion for open patellar fracture. Dé- described. Early knee motion and cation related to patellar fracture.6,42 bridement should be meticulous, full weight bearing in a hinged knee Many surgeons advocate internal with removal of all devitalized tissue. brace is recommended in patients fixation to allow early ROM; how- 14,20 However, soft-tissue attachments to with stable fixation. Postopera- ever, internal fixation has not been remaining bone fragments must be tive continuous passive motion is proved to mitigate stiffness. Others maintained. All attempts are made to thought to reduce stiffness and im- have reported that length of immobi- preserve bone; patellectomy is re- prove healing of articular cartilage.6 lization does not affect stiffness; served for substantial bone loss. Pri- Prolonged immobilization is gener- thus, the cause of stiffness remains mary closure should be performed ally discouraged. unclear.31 Substantial knee extensor when tension-free closure is possible. For fractures with stable internal weakness has been observed with to- Should skin grafting or flap coverage fixation, we recommend early phys- tal and partial patellectomy. Internal be required, it is done within 7 days iotherapy and weight bearing as tol- fixation is associated with less exten- to minimize the risk of infection. erated while limiting flexion to 30° sor weakness; however, residual ar-

April 2011, Vol 19, No 4 205 Patellar Fractures in Adults ticular step-off and pain have been ploying cannulated screws enable compendium: 2007. Orthopaedic shown to correlate with decreased early ROM and are associated with Trauma Association classification, database and outcomes committee. quadriceps strength in patients the best outcomes. Every effort J Orthop Trauma 2007;21(10 suppl):S1- treated with internal fixation.36,45 should be made to preserve patellar S133. Nonunion is rare in closed frac- bone stock. Total patellectomy 9. Braun W, Wiedemann M, Rüter A, tures. Most series report rates of should be avoided except in rare in- Kundel K, Kolbinger S: Indications and results of nonoperative treatment of ≤1%; however, open fractures may stances. Open fractures may be man- patellar fractures. Clin Orthop Relat Res be complicated by nonunion in up to aged successfully with antibiotics, 1993;(289):197-201. 7% of cases.6,40,42 Deep infection is débridement, and early fixation. 10. Pritchett JW: Nonoperative treatment of These fractures are associated with a widely displaced patella fractures. Am J rare, as well (zero to 5%); however, Knee Surg 1997;10(3):145-148. the rate is higher for open fractures higher rate of complications than are 11. Lotke PA, Ecker ML: Transverse 38,40 (11%). closed fractures. fractures of the patella. Clin Orthop Reported rates of radiographic os- Relat Res 1981;(158):180-184. teoarthritis (OA) are rare in the re- 12. Gardner MJ, Griffith MH, Lawrence 46 References BD, Lorich DG: Complete exposure of cent literature. In 1964, Sorensen the articular surface for fixation of reported a 70% rate of patellofemo- patellar fractures. J Orthop Trauma Evidence-based Medicine: Levels of ral OA at 10- to 30-year follow-up. 2005;19(2):118-123. evidence are described in the table of In 1972, Boström1 reported signifi- 13. Muller ME, Allgower M, Schneider R, contents. In this article, reference 7 is cantly less OA with nonsurgical Willeneger H: Manual of Internal a level I study. References 25, 27, Fixation: Techniques Recommended by management compared with surgical and 37 are level II studies. Refer- the AO Group. Berlin, Germany, management at 9-year follow-up Springer, 1979, pp 248-253. ences 24, 35, 36, 39, and 45 are level (16% versus 35%, respectively). 14. Weber MJ, Janecki CJ, McLeod P, III studies. References 1, 9-12, 20, However, he found similar rates of Nelson CL, Thompson JA: Efficacy of 23, 26, 28-31, 34, 38, 40-42, and 46 various forms of fixation of transverse OA when comparing osteosynthesis are level IV studies. fractures of the patella. J Bone Joint Surg with partial patellectomy (32% ver- Am 1980;62(2):215-220. References printed in bold type are sus 35%, respectively). In 1990, 15. 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