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Periarticular Nonunions Around the Knee
Periarticular Nonunions Around the Knee Enes M. Kanlic, MD,* Oytun D. Tunç, MD,† and Miguel A. Pirela-Cruz, MD* Up to 5% of knee fractures do not heal primarily at the expected time (delayed union) or fail to achieve healing (nonunion). The causes and treatment of disturbed bone healing in the distal femur, proximal tibia, and patella and in an increasing number of periprosthetic fractures have been discussed. Infection exclusion and/or eradication, reestablishment of axis, alignment and rotation, rigid fixation with fixed-angle devices and interfragmentary screws, bone grafting, arthrolysis, and early range of motion exercises are all necessary steps for good recovery. Illustrative cases have been presented with authors’ preferences in the surgical treatment supported by recent publications. Oper Tech Orthop 18:121-127 © 2008 Elsevier Inc. All rights reserved. KEYWORDS knee nonunion, distal femur, proximal tibia, patella, periprosthetic knee fractures
T
he knee is a hinged joint that plays an important role in human motion and activities. Injuries are common, especially among the young, active population. Metaphyseal, cancellous, well-vascularized bone with a lot of softtissue attachments (distal femur, patella, proximal tibia, and fibula) has a high tendency of healing provided a certain degree of stability. A motion between main fragments has to be minimized or completely abolished to allow union to occur. Unfortunately, it is not sufficient just to have the fractures healed in order for the joint to stay viable. Tendons around the knee have to move to preserve their function and maintain muscles strength. Moreover, scarred tendons with a limited range of motion may severely impair function in the face of well-united fracture. Motion occurs within the constrained range and is guided by ligaments (intact, in healing, or repaired) and bone (intact or stabilized by hardware).1-5 The joint will deteriorate and result in disabling posttraumatic arthritis (pain and stiffness) if (1) the articular surfaces are not congruent (fractures with step offs more than 2 mm or condylar widening more than 5 mm); (2) the knee is not stable and aligned well (varus is worse than valgus), and/or (3) the biology of cartilage is not normal (regenerate fibrocartilage instead of hyaline cartilage, menisci damaged or missing).6-9
*Department of Orthopaedic Surgery and Rehabilitation, TTUHSC, El Paso, TX. †Orthopaedic Department, Baltalimaný Kemik Hastanesi, Istanbul, Turkey. Address reprint requests to Enes M. Kanlic, MD, Department of Orthopaedic Surgery and Rehabilitation, TTUHCS, 4801 Alberta Avenue, El Paso, TX 79905. E-mail: [email protected]
1048-6666/08/$-see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1053/j.oto.2008.09.001
In summary, the goals of the treating team are to preserve/ repair neurovascular structures and to provide enough stability to reduced fragments to allow for safe and comfortable healing and rehabilitation. Early active and passive range of motion exercises will improve the nourishment of the cartilage, and the damaged ligaments will heal in more functional positions. All together, this will make return to a sufficient function possible (arc of motion from 0°-120°) at the time when bone healing occurs (2-3 months). Osteoporosis is very prevalent, and bones in elderly population brake easily even with law energy trauma. Forty percent of woman and 14% of men older than 50 years will sustain fractures related to reduction in their bone mass.10 Crushing leaves defects and instability in milieu of “empty” trabeculae with very poor healing potential. The knee is the most commonly replaced joint, and periprosthetic fractures occur (0.3% to 2.5% of patients) with a whole new set of problems requiring complex solutions.11 Reported periarticular knee nonunion rates in the recent literature range from 0% to 4% (in the past, it was 10%).12
Materials and Discussion The most common local causes of delayed union and nonunion are consequences of the following: 1. Trauma: high-energy impact with devascularization and destruction of bone mass and surrounding soft tissues 2. Host: patient characteristics (diabetes, inflammatory arthritis, vasculopathy, and so on) and drugs (steroids, nonsteroidal antiinflammatories, smoking, alcohol, and so on). 121
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Figure 1 (A) Anteroposterior (AP) view of the distal femur. (B) Lateral x-ray and computed tomography scan (C) in a 10-month old, grade II open, high-energy type of supracondylar femur fracture, with a developed nonunion in a 63-year-old laborer. Three months after, an AP (D) and lateral view (E) of the healed nonunion treated with a dynamic condylar screw, axial compression, interfragmentary screw, and autologous bone graft.
3. Treatment: inadequate treatment (too much mobility at the fracture level) and premature weight bearing (patient inability or lack of willingness to restrain the weight bearing until sufficient bone healing occurs). 4. Infection (0%-7%)12: open fractures (5%-10% in distal femur, up to 20% get infected8; and up to 25% in highenergy plateau fractures with deep infection rates up to 22%13-16) and complication of surgery.17,18 A diagnosis is made when (1) there is presence of pain with weight bearing at the (nonhealing) fracture level, (2) there is no improvement of callus formation on 3 consequent x-ray monthly follow-ups and/or there is absence of cortical bridging at the fracture level (three cortices on 2 orthogonal x-ray views or computer tomogram, what should happen up to 6 months), and (3) if there are no obvious clinical signs of infection, (drainage and redness). Routine diagnostic procedure have to be used for evaluation/exclusion of infection (C-reactive protein, joint aspiration with weight blood cells count and cultures, biopsy, and eventually bone scans). Therapy will depend on the type of nonunion. If vascularity is preserved (a callus is visible in the form of “elephant’s foot” [hypertrophic] or “horse’s hoof” [eutrophic]), better bone contact is needed (improved mechanical stability). It is usually achieved by more rigid fixation (fixed-angle devices and interfragmentary screws) (Fig. 1). Mobility of the knee is necessary to be reestablished at the time of nonunion exploration by either arthrolysis or quadricepsplasty in order to prevent a long lever arm on the opposite side of the nonunion, which can jeopardize the healing process. A long “stiff knee shaft” segment will make any fixation of a short segment (distal femur or proximal tibia) insufficient. In a younger person and a destroyed joint, arthrodesis might be necessary.8
When vascularity is diminished (oligotrophic, atrophic, and nonunions with defect), besides secure bone fixation, additional biological stimulus is necessary. We could use techniques of decortication and bone graft (including vascularized free bone autotransplant),19 or controlled micromotion (ring fixator and dynamized nail). Bone morphogenetic proteins (BMP-1 and BMP-7), exogenous electromagnetic fields1,20 and low-intensity pulsed ultrasound could be applied as well.21 In cases of infection, if it is localized, without systemic symptoms (fever, chills), and bone-bridging callus formation is progressing, hardware should stay in (with or without suppressive antibiotic therapy targeting specific bacteria) until bone healing occurs. If infection cannot be controlled without removing the hardware, debridement throughout the infected and necrotic tissue and long-term antibiotic therapy are necessary. The alternative ways of fixation have to be used (external fixators and antibiotic spacers with bracing).22 In situations where infection is fully controlled (no positive clinical and laboratory signs are present in the absence of antibiotics for a couple of weeks or months), then renewed open reduction and internal fixation, when joint space is still preserved and metaphyseal segment of sufficient size for healing, is available in a young person (Fig. 2). Bone healing– enhancing measures (grafts and BMPs) are necessary. Joint replacements (tumor type of prosthesis) are indicated in a sterile environment and in an elderly person. Knee fusion is a salvage procedure in a bad infection (mixed, gram-negative, resistant flora) and a compromised host (immunodeficient) (Fig. 3). Amputation is rarely the only solution.
Distal Femur Using the indirect reduction techniques, Bellabarba et al23 were able to cure all 20 consecutive patients with nonunion
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Figure 2 (A) A lateral view 4 months after the removal of an infected locking plate applied for fixation of a grade II open high-energy fracture in a 54-year-old man. A lateral (B) and AP view (C) of a reconstructed nonunion of the distal femur with a preserved joint, cerclage cable, and bone anchors used to secure mobilized ligament patellae. (D) A longstanding AP view of the femur and proximal tibia shows good alignment of the construct and the joint.
of the distal femur with significant clinical improvement. Forty-five percent needed an autologous cancellous bone graft, and just one patient with a history of osteomyelitis has developed deep infection. Nonunions were approached through previous incisions (to avoid additional stripping and devascularization of fragments). Shingling or petaling of adjacent cortex was done with osteotomes, and the medullary canal was opened on both sides with drills and osteotomes.
Fixed-angle devices (dynamic condylar screw, 95° condylar blade plate, or locking condylar plate) were used to fix the distal fragment after a reduction in good position. Axial compression was used routinely and an interfragmentary compression screw was used whenever possible to achieve the maximum contact and stability of the fragments. Autologous bone grafting was applied in atrophic and oligotrophic nonunions.
Figure 3 (A) An AP computer tomogram–reconstructed view of a unicondylar intra-articular distal femur fracture in a 56-year-old immunocompromised woman. (B) An AP view after fixation with a locked plate and a small lag screw. (C) An AP view 4 months later with the hardware removed because of infection, displacement at the nonunion level, and a noticeable joint narrowing of the medial compartment. (D and E) AP and lateral views of the knee 3 months after fusion surgery with 2 orthogonally locked plates and present antibiotic beads.
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Figure 4 (A) A lateral view of the knee showing a 1-year-old patella nonunion with an escaped distal fragment and the inability of active extension in a 67-year-old woman. (B) A lateral view 7 months after revision surgery with healed nonunion, some central articular defect, and 1 Kirschner wire migrated proximally. (C) A clinical photograph with almost full, active knee extension without any symptoms.
Wang and Weng24 have used allograft struts when nonunion was associated with failure of osteosynthesis and either severe osteopenia or a unicortical bone defect of ⱖ2 cm. All 13 nonunions have healed. Chapman and Finkemeier25 using an anterior extensile approach add an anteromedial plate “if the bone quality of bone is poor and fixation with an interfragmentary screw cannot be secured.” Gardner et al26 have introduced te removal of all fibrous tissue surrounding nonunion, arthrolysis (removal of scar tissue
from the suprapatellar pouch) when necessary and postoperative continuous passive mobilization. All nonunions were packed with either autologous bone graft or demineralized bone matrix.
Patella The nonunion of patella develops in 2.4% to 12.5% of patella fractures.26 More stable fixation is necessary for a younger pop-
Figure 5 (A) An AP view of the knee with a broken distal femur, proximal tibia, and fibula with disrupted soft tissues in a 56-year-old pedestrian woman. (B) An AP view of the knee and lag with a present retrograde femoral nail and hybrid external fixator in place. (C) An AP leg view with established oligotrophic nonunion of proximal tibia 7 months after the injuries. (D and E) Fourteen months after injuries with healed nonunion treated with a 90° blade plate, axial compression, leg screw, and bone graft. This patient functions well 8 years thereafter.
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Figure 6 (A) An AP view of the knee 5 months after an attempt of open-wedge osteotomy with a developed nonunion in a 43-year-old patient. (B) An intraoperative AP view at the time of deformity correction and after nonunion mobilization. (C) An AP view with a healed nonunion gap filled up with demineralized bone matrix. (D) A clinical photograph of the patient without symptoms 14 months after revision surgery.
ulation especially if there is a gap larger than 4 mm (Fig. 4). If severe and symptomatic cartilage damage is found, partial or total patellectomy might be considered. Quadriceps hypotrophy with weakness and pain is a common complaint.27-29
Tibial Plateau Tibial plateau fractures are common, but nonunion is rare; it usually occurs in high-energy metadiaphyseal displaced fractures (Fig. 5), not well-executed high tibial osteotomies (Fig. 6), or if fractures are complicated by infection. Treatment principles are the same as discussed for distal femur fractures. In cases in which the joint is destroyed and when there is no history of infection, joint arthroplasty is indicated, even at a younger age. Malalignment, defects, instability, retained hardware, and poor surrounding soft tissues make it much more complex than is the case in primary joint replacements. Published reoperation rates are up to 21%. Fusion and amputation are salvage procedures of the last resort.30
There is a small amount of bone left with questionable circulation (medial incision, lateral releases). Those cases could be approached as follows: (1) “conscious neglect,” if some extensor mechanism function is still preserved (supportive bracing is needed waiting for building of the scar tissue, restrain of active extension), (2) cerclage wires for fixation of patella if there is enough bone left (with patella insert retained when stable or without it when loose), (3) excision of patella with extensor mechanism reconstruction when patella button is loose and no enough patellar bone left, or (4) bone grafting and rebuilding new patella when the patient is younger and more demanding (for increased strength of extension).32 ● If total knee prosthesis is unstable, then a different type of device has to be used (revision, total constrained when medial and lateral ligaments are preserved, or hinge type of implant when there is no distal femur or proximal tibia with attached ligaments left; Fig. 7).12,33
Periprosthetic Knee Nonunions If the prosthesis is stable (in good contact with surrounding bone in a quantity sufficient for healing with diaphyseal segment) and if there is no hardware from previous attempts of fixation, the following will happen: 1. Fixation will be undertaken with proven “metaphyseal types of implants (“fixed-angle” devices for distal femur and proximal tibia; eventually, retrograde nails for supracondylar femur fractures with “open box” femoral component and distal segment accepting two blocking screws). Infection has to be excluded first. Ricci et al31 found that 3 of 24 (12.5%) patients in their series have developed nonunion; 2 of them had infection and 1 had diabetes mellitus. 2. Fractured patella with present patellar button (mostly loose) has a very high tendency for developing nonunion.
Conclusion Everything possible (no infection and sound biological fixation allowing for early range of motion) must be done to avoid periarticular knee nonunion. When fracture does not have tendency of healing, it has to be recognized, diagnosed, understood, and treated accordingly. More fixation (controlled dynamization or rigidity) is needed in well-vascularized milieu (hypertrophic callus). Besides stabilization, stimulating new bone-forming interventions are necessary when there are no signs of forming the hard callus (oligotrophic, atrophic, or nonunion with defect). Localized infection in well-fixed bone fragments (no loose or broken hardware) could result in satisfactory bony healing. Loose implants have to be replaced with an external type of fixation after repeated
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Figure 7 (A and B) AP and lateral views of the knee and the distal femur with failed fixation of the periprosthetic supracondylar femur fracture after 6 months in a 76-year-old woman. (C) An AP view of the knee with an antibiotic spacer placed after removal of the infected hardware. (D) An AP view of the knee with hinged knee prosthesis in place, a lateral tibial locking plate for intraoperative crack, and a stress-protecting femoral strut graft.
debridements of the necrotic tissues. Targeted antibiotic long-term therapy must be used. Periprosthetic nonunions with stable implants require osteosynthesis, and there is a high chance of healing. In cases when prosthesis– bone contact is minimal or lacking, a more constrained, revision-type of knee replacement is necessary (Fig. 7).
10. 11.
12.
References 1. Moholkar KD, Ziran BH: Local complications, in Bucholz RW, Heckman JD, Court-Brown CM (eds): Rockwood and Green’s Fractures in Adults (ed 6). Philadelphia, PA, Lippincott Williams & Wilkins, 2006, pp 565-609 2. McKee MD, Ochsner PE: Aseptic nonunion, in Rüedi TP, Buckley RE, Moran CG (eds): AO Principles of Fracture Management, ed 2, Thieme. Stuttgart, 2007, pp 505-520 3. Christodoulou A, Terzidis I, Ploumis A, et al: Supracondylar femoral fractures in elderly patients treated with the dynamic condylar screw and the retrograde intramedullary nail: A comparative study of the two methods. Arch Orthop Trauma Surg 125:73-79, 2005 4. Haidukewych G, Sems SA, Huebner D, et al: Results of polyaxial locked-plate fixation of periarticular fractures of the knee. J Bone Joint Surg Am 89:614-620, 2007 5. Haidukewych G, Sems SA, Huebner D, et al: Results of polyaxial locked-plate fixation of periarticular fractures of the knee. Surgical technique. J Bone Joint Surg Am 90:117-134, 2008 (suppl 2) 6. Tscherne H, Lobenhoffer P: Tibial plateau fractures. Management and expected results. Clin Orthop Relat Res 292:87-100, 1993 7. Probe RA: Lower extremity angular malunion: Evaluation and surgical correction. J Am Acad Orthop Surg 11:302-311, 2003 8. O“Brien, Meek RN, Blachut P, et al: Fractures of the distal femur, in Bucholz RW, Heckman JD, Court-Brown CM (eds): Rockwood and Green’s Fractures in Adults (ed 6). Philadelphia, PA, Lippincott Williams & Wilkins, 2006, pp 1915-1967 9. Stannard JP, Martin SL: Tibial plateau fractures, in Stannard JP,
13.
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18. 19.
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Schmidt AH, Kregor PJ (eds): Surgical Treatment of Orthopaedic Trauma. New York, NY, Thieme, 2007, pp 712-741 Eastell R, Lambert H: Strategies for skeletal health in the elderly. Proc Nutr Soc 61:173-180, 2002 Kyle RF, Haas JC, Yoon P: Periprosthetic femur fractures, in Wiss DA (ed): Fractures (ed 2). Philadelphia, PA, Lippincott Williams & Wilkins, 2006, pp 765-782 Krettek C, Helfet DL: Fractures of the distal femur, in Browner BD, Jupiter JB, Levine AM, et al (eds): Skeletal Trauma (ed 3). Philadelphia, PA, Saunders, 2003, pp 1957-2011 Cole PA, Zlowodzki M, Kregor PJ: Treatment of proximal tibia fractures using the less invasive stabilization system: Surgical experience and early clinical results in 77 fractures. J Orthop Trauma 18:528-535, 2004 Phisitkul P, McKinley TO, Nepola JV, et al: Complications of locking plate fixation in complex proximal tibia injuries. J Orthop Trauma 21:83-91, 2007 Stannard JP: Proximal tibia fractures: Locked plating, in Wiss DA (ed): Fractures (ed 2). Philadelphia, PA, Lippincott Williams & Wilkins, 2006, pp 439-451 Egol KA, Koval KJ: Fractures of proximal tibia, in Bucholz RW, Heckman JD, Court-Brown CM (eds). Rockwood and Green’s Fractures in Adults (ed 6). Philadelphia, PA, Lippincott Williams & Wilkins, 2006, pp 2000-2029 Miranda MA, Moon MS: Treatment strategy for nonunions and malunions, in Stannard JP, Schmidt AH, Kregor PJ (eds). Surgical Treatment of Orthopaedic Trauma. New York, NY, Thieme, 2007, pp 77100 Blease R, Kanlic E: Management of open fractures. Bosn J Basic Med Sci 5:14-21, 2005 Lai D, Chen CM, Chiu FY, et al: Reconstruction of juxta-articular huge defects of distal femur with vascularized fibular bone graft and Ilizarov’s distraction osteogenesis. J Trauma 62:166-173, 2007 Beutler S, Regel G, Pape HC, et al: Extracorporeal shock wave therapy for delayed union of fractures of the femoral shaft treated by wave-plate
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osteosynthesis—Preliminary results of a prospective cohort study. Unfallchirurg 102:839-847, 1999 Jingushi S, Mizuno K, Matsushita T, et al: Low-intensity pulsed ultrasound treatment for postoperative delayed union or nonunion of long bone fractures. J Orthop Sci 12:35-41, 2007 Johnson EE, Buckley RE: Chronic infection and infected nonunion, in Rüedi TP, Buckley RE, Moran CG (eds). AO Principles of Fracture Management (ed 2). Stuttgart, Thieme, 2007, pp 543-555 Bellabarba C, Ricci WM, Bolhofner BR: Reduction and plating of distal femoral nonunions. J Orthop Trauma 16:287-296, 2002 Wang JW, Weng LH: Treatment od fistal femoral nonunion with internal fixation, cortical allograft struts, and autogenous bone-grafting. J Bone Joint Surg Am 85:436-440, 2003 Chapman MW, Finkemeier CG: Treratment of supracondylar nonunions of the femur with plate fixation and bone graft. J Bone Joint Surg Am 81:1217-1228, 1999 Gardner MJ, Toro-Arbelaez JB, Harrison M, et al: Open reduction and intenal fixation of distal femoral nonunions: Long-term functional outcomes following a treatment protocol. J Trauma 64:434-438, 2008 Harris RM: Fractures of the patella and injuries to the extensor mech-
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anism, in Bucholz RW, Heckman JD, Court-Brown CM (eds): Rockwood and Green’s Fractures in Adults (ed 6). Philadelphia, PA, Lippincott Williams & Wilkins, 2006, pp 1969-1997 Archdeacon MT, Sanders RW: Patella fractures and extensor mechanism injuries, in Browner BD, Jupiter JB, Levine AM, et al (eds): Skeletal Trauma (ed 3). Philadelphia, PA, Saunders, 2003, pp 2013-2044 Pirela-Cruz M, Kanlic EM: Injuries to the knee extensor mechanism, in Elstrom JA, Virkus VV, Pankovich AM (eds): Handbook of Fractures (ed 3). New York, NY, McGraw-Hill, 2005, pp 332-339 Weiss NG, Parvizi J, Trousdale RT, et al: Total knee arthroplasty in patients with a prior fracture of the tibial plateau. J Bone Joint Surg Am 85:218-221, 2003 Ricci WM, Loftus T, Cox C, et al: Locked plates combined with minimally invasive insertion technique for the treatment of periprosthetic supracondylar femur fractures above a total knee arthroplasty. J Orthop Trauma 20:190-196, 2006 Hanssen AD: Bone-grafting for severe patellar bone loss during revision knee arthroplasty. J Bone Joint Surg Am 83A2:171-176, 2001 Henry SL, Booth RE: Management of supracondylar fractures above total knee prosthesis. Tech Orthop 9:243-252, 1994
T
he knee is a hinged joint that plays an important role in human motion and activities. Injuries are common, especially among the young, active population. Metaphyseal, cancellous, well-vascularized bone with a lot of softtissue attachments (distal femur, patella, proximal tibia, and fibula) has a high tendency of healing provided a certain degree of stability. A motion between main fragments has to be minimized or completely abolished to allow union to occur. Unfortunately, it is not sufficient just to have the fractures healed in order for the joint to stay viable. Tendons around the knee have to move to preserve their function and maintain muscles strength. Moreover, scarred tendons with a limited range of motion may severely impair function in the face of well-united fracture. Motion occurs within the constrained range and is guided by ligaments (intact, in healing, or repaired) and bone (intact or stabilized by hardware).1-5 The joint will deteriorate and result in disabling posttraumatic arthritis (pain and stiffness) if (1) the articular surfaces are not congruent (fractures with step offs more than 2 mm or condylar widening more than 5 mm); (2) the knee is not stable and aligned well (varus is worse than valgus), and/or (3) the biology of cartilage is not normal (regenerate fibrocartilage instead of hyaline cartilage, menisci damaged or missing).6-9
*Department of Orthopaedic Surgery and Rehabilitation, TTUHSC, El Paso, TX. †Orthopaedic Department, Baltalimaný Kemik Hastanesi, Istanbul, Turkey. Address reprint requests to Enes M. Kanlic, MD, Department of Orthopaedic Surgery and Rehabilitation, TTUHCS, 4801 Alberta Avenue, El Paso, TX 79905. E-mail: [email protected]
1048-6666/08/$-see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1053/j.oto.2008.09.001
In summary, the goals of the treating team are to preserve/ repair neurovascular structures and to provide enough stability to reduced fragments to allow for safe and comfortable healing and rehabilitation. Early active and passive range of motion exercises will improve the nourishment of the cartilage, and the damaged ligaments will heal in more functional positions. All together, this will make return to a sufficient function possible (arc of motion from 0°-120°) at the time when bone healing occurs (2-3 months). Osteoporosis is very prevalent, and bones in elderly population brake easily even with law energy trauma. Forty percent of woman and 14% of men older than 50 years will sustain fractures related to reduction in their bone mass.10 Crushing leaves defects and instability in milieu of “empty” trabeculae with very poor healing potential. The knee is the most commonly replaced joint, and periprosthetic fractures occur (0.3% to 2.5% of patients) with a whole new set of problems requiring complex solutions.11 Reported periarticular knee nonunion rates in the recent literature range from 0% to 4% (in the past, it was 10%).12
Materials and Discussion The most common local causes of delayed union and nonunion are consequences of the following: 1. Trauma: high-energy impact with devascularization and destruction of bone mass and surrounding soft tissues 2. Host: patient characteristics (diabetes, inflammatory arthritis, vasculopathy, and so on) and drugs (steroids, nonsteroidal antiinflammatories, smoking, alcohol, and so on). 121
E.M. Kanlic, O.D. Tunç, and M.A. Pirela-Cruz
122
Figure 1 (A) Anteroposterior (AP) view of the distal femur. (B) Lateral x-ray and computed tomography scan (C) in a 10-month old, grade II open, high-energy type of supracondylar femur fracture, with a developed nonunion in a 63-year-old laborer. Three months after, an AP (D) and lateral view (E) of the healed nonunion treated with a dynamic condylar screw, axial compression, interfragmentary screw, and autologous bone graft.
3. Treatment: inadequate treatment (too much mobility at the fracture level) and premature weight bearing (patient inability or lack of willingness to restrain the weight bearing until sufficient bone healing occurs). 4. Infection (0%-7%)12: open fractures (5%-10% in distal femur, up to 20% get infected8; and up to 25% in highenergy plateau fractures with deep infection rates up to 22%13-16) and complication of surgery.17,18 A diagnosis is made when (1) there is presence of pain with weight bearing at the (nonhealing) fracture level, (2) there is no improvement of callus formation on 3 consequent x-ray monthly follow-ups and/or there is absence of cortical bridging at the fracture level (three cortices on 2 orthogonal x-ray views or computer tomogram, what should happen up to 6 months), and (3) if there are no obvious clinical signs of infection, (drainage and redness). Routine diagnostic procedure have to be used for evaluation/exclusion of infection (C-reactive protein, joint aspiration with weight blood cells count and cultures, biopsy, and eventually bone scans). Therapy will depend on the type of nonunion. If vascularity is preserved (a callus is visible in the form of “elephant’s foot” [hypertrophic] or “horse’s hoof” [eutrophic]), better bone contact is needed (improved mechanical stability). It is usually achieved by more rigid fixation (fixed-angle devices and interfragmentary screws) (Fig. 1). Mobility of the knee is necessary to be reestablished at the time of nonunion exploration by either arthrolysis or quadricepsplasty in order to prevent a long lever arm on the opposite side of the nonunion, which can jeopardize the healing process. A long “stiff knee shaft” segment will make any fixation of a short segment (distal femur or proximal tibia) insufficient. In a younger person and a destroyed joint, arthrodesis might be necessary.8
When vascularity is diminished (oligotrophic, atrophic, and nonunions with defect), besides secure bone fixation, additional biological stimulus is necessary. We could use techniques of decortication and bone graft (including vascularized free bone autotransplant),19 or controlled micromotion (ring fixator and dynamized nail). Bone morphogenetic proteins (BMP-1 and BMP-7), exogenous electromagnetic fields1,20 and low-intensity pulsed ultrasound could be applied as well.21 In cases of infection, if it is localized, without systemic symptoms (fever, chills), and bone-bridging callus formation is progressing, hardware should stay in (with or without suppressive antibiotic therapy targeting specific bacteria) until bone healing occurs. If infection cannot be controlled without removing the hardware, debridement throughout the infected and necrotic tissue and long-term antibiotic therapy are necessary. The alternative ways of fixation have to be used (external fixators and antibiotic spacers with bracing).22 In situations where infection is fully controlled (no positive clinical and laboratory signs are present in the absence of antibiotics for a couple of weeks or months), then renewed open reduction and internal fixation, when joint space is still preserved and metaphyseal segment of sufficient size for healing, is available in a young person (Fig. 2). Bone healing– enhancing measures (grafts and BMPs) are necessary. Joint replacements (tumor type of prosthesis) are indicated in a sterile environment and in an elderly person. Knee fusion is a salvage procedure in a bad infection (mixed, gram-negative, resistant flora) and a compromised host (immunodeficient) (Fig. 3). Amputation is rarely the only solution.
Distal Femur Using the indirect reduction techniques, Bellabarba et al23 were able to cure all 20 consecutive patients with nonunion
Periarticular nonunions around the knee
123
Figure 2 (A) A lateral view 4 months after the removal of an infected locking plate applied for fixation of a grade II open high-energy fracture in a 54-year-old man. A lateral (B) and AP view (C) of a reconstructed nonunion of the distal femur with a preserved joint, cerclage cable, and bone anchors used to secure mobilized ligament patellae. (D) A longstanding AP view of the femur and proximal tibia shows good alignment of the construct and the joint.
of the distal femur with significant clinical improvement. Forty-five percent needed an autologous cancellous bone graft, and just one patient with a history of osteomyelitis has developed deep infection. Nonunions were approached through previous incisions (to avoid additional stripping and devascularization of fragments). Shingling or petaling of adjacent cortex was done with osteotomes, and the medullary canal was opened on both sides with drills and osteotomes.
Fixed-angle devices (dynamic condylar screw, 95° condylar blade plate, or locking condylar plate) were used to fix the distal fragment after a reduction in good position. Axial compression was used routinely and an interfragmentary compression screw was used whenever possible to achieve the maximum contact and stability of the fragments. Autologous bone grafting was applied in atrophic and oligotrophic nonunions.
Figure 3 (A) An AP computer tomogram–reconstructed view of a unicondylar intra-articular distal femur fracture in a 56-year-old immunocompromised woman. (B) An AP view after fixation with a locked plate and a small lag screw. (C) An AP view 4 months later with the hardware removed because of infection, displacement at the nonunion level, and a noticeable joint narrowing of the medial compartment. (D and E) AP and lateral views of the knee 3 months after fusion surgery with 2 orthogonally locked plates and present antibiotic beads.
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Figure 4 (A) A lateral view of the knee showing a 1-year-old patella nonunion with an escaped distal fragment and the inability of active extension in a 67-year-old woman. (B) A lateral view 7 months after revision surgery with healed nonunion, some central articular defect, and 1 Kirschner wire migrated proximally. (C) A clinical photograph with almost full, active knee extension without any symptoms.
Wang and Weng24 have used allograft struts when nonunion was associated with failure of osteosynthesis and either severe osteopenia or a unicortical bone defect of ⱖ2 cm. All 13 nonunions have healed. Chapman and Finkemeier25 using an anterior extensile approach add an anteromedial plate “if the bone quality of bone is poor and fixation with an interfragmentary screw cannot be secured.” Gardner et al26 have introduced te removal of all fibrous tissue surrounding nonunion, arthrolysis (removal of scar tissue
from the suprapatellar pouch) when necessary and postoperative continuous passive mobilization. All nonunions were packed with either autologous bone graft or demineralized bone matrix.
Patella The nonunion of patella develops in 2.4% to 12.5% of patella fractures.26 More stable fixation is necessary for a younger pop-
Figure 5 (A) An AP view of the knee with a broken distal femur, proximal tibia, and fibula with disrupted soft tissues in a 56-year-old pedestrian woman. (B) An AP view of the knee and lag with a present retrograde femoral nail and hybrid external fixator in place. (C) An AP leg view with established oligotrophic nonunion of proximal tibia 7 months after the injuries. (D and E) Fourteen months after injuries with healed nonunion treated with a 90° blade plate, axial compression, leg screw, and bone graft. This patient functions well 8 years thereafter.
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Figure 6 (A) An AP view of the knee 5 months after an attempt of open-wedge osteotomy with a developed nonunion in a 43-year-old patient. (B) An intraoperative AP view at the time of deformity correction and after nonunion mobilization. (C) An AP view with a healed nonunion gap filled up with demineralized bone matrix. (D) A clinical photograph of the patient without symptoms 14 months after revision surgery.
ulation especially if there is a gap larger than 4 mm (Fig. 4). If severe and symptomatic cartilage damage is found, partial or total patellectomy might be considered. Quadriceps hypotrophy with weakness and pain is a common complaint.27-29
Tibial Plateau Tibial plateau fractures are common, but nonunion is rare; it usually occurs in high-energy metadiaphyseal displaced fractures (Fig. 5), not well-executed high tibial osteotomies (Fig. 6), or if fractures are complicated by infection. Treatment principles are the same as discussed for distal femur fractures. In cases in which the joint is destroyed and when there is no history of infection, joint arthroplasty is indicated, even at a younger age. Malalignment, defects, instability, retained hardware, and poor surrounding soft tissues make it much more complex than is the case in primary joint replacements. Published reoperation rates are up to 21%. Fusion and amputation are salvage procedures of the last resort.30
There is a small amount of bone left with questionable circulation (medial incision, lateral releases). Those cases could be approached as follows: (1) “conscious neglect,” if some extensor mechanism function is still preserved (supportive bracing is needed waiting for building of the scar tissue, restrain of active extension), (2) cerclage wires for fixation of patella if there is enough bone left (with patella insert retained when stable or without it when loose), (3) excision of patella with extensor mechanism reconstruction when patella button is loose and no enough patellar bone left, or (4) bone grafting and rebuilding new patella when the patient is younger and more demanding (for increased strength of extension).32 ● If total knee prosthesis is unstable, then a different type of device has to be used (revision, total constrained when medial and lateral ligaments are preserved, or hinge type of implant when there is no distal femur or proximal tibia with attached ligaments left; Fig. 7).12,33
Periprosthetic Knee Nonunions If the prosthesis is stable (in good contact with surrounding bone in a quantity sufficient for healing with diaphyseal segment) and if there is no hardware from previous attempts of fixation, the following will happen: 1. Fixation will be undertaken with proven “metaphyseal types of implants (“fixed-angle” devices for distal femur and proximal tibia; eventually, retrograde nails for supracondylar femur fractures with “open box” femoral component and distal segment accepting two blocking screws). Infection has to be excluded first. Ricci et al31 found that 3 of 24 (12.5%) patients in their series have developed nonunion; 2 of them had infection and 1 had diabetes mellitus. 2. Fractured patella with present patellar button (mostly loose) has a very high tendency for developing nonunion.
Conclusion Everything possible (no infection and sound biological fixation allowing for early range of motion) must be done to avoid periarticular knee nonunion. When fracture does not have tendency of healing, it has to be recognized, diagnosed, understood, and treated accordingly. More fixation (controlled dynamization or rigidity) is needed in well-vascularized milieu (hypertrophic callus). Besides stabilization, stimulating new bone-forming interventions are necessary when there are no signs of forming the hard callus (oligotrophic, atrophic, or nonunion with defect). Localized infection in well-fixed bone fragments (no loose or broken hardware) could result in satisfactory bony healing. Loose implants have to be replaced with an external type of fixation after repeated
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Figure 7 (A and B) AP and lateral views of the knee and the distal femur with failed fixation of the periprosthetic supracondylar femur fracture after 6 months in a 76-year-old woman. (C) An AP view of the knee with an antibiotic spacer placed after removal of the infected hardware. (D) An AP view of the knee with hinged knee prosthesis in place, a lateral tibial locking plate for intraoperative crack, and a stress-protecting femoral strut graft.
debridements of the necrotic tissues. Targeted antibiotic long-term therapy must be used. Periprosthetic nonunions with stable implants require osteosynthesis, and there is a high chance of healing. In cases when prosthesis– bone contact is minimal or lacking, a more constrained, revision-type of knee replacement is necessary (Fig. 7).
10. 11.
12.
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