Total Knee Arthroplasty for Supracondylar Femur Fractures

David Backstein M.D., MEd, FRCSC
Assistant Professor, Department of Surgery
Hip & Knee Reconstruction, Mount Sinai Hospital
Director of Undergraduate Education, Department of Surgery,
University of Toronto
Toronto, ON

Do clinical scenarios exist where one might choose primary TKA as a means of treating a supracondylar fracture of the femur? The answer to this question is yes, although this is certainly not a common method of management for this problem. Complex supracondylar fractures of the femur are often difficult to manage with standard fixation techniques, particularly in the elderly with osteoporotic or osteopenic bone1,2,3,4 and associated comorbidities. In addition, these same factors may increase the incidence of fracture nonunion5. Despite new and improved techniques for osteosynthesis, poor outcomes are still very common in the geriatric population6. An alternative option to internal fixation, which is certainly less frequently employed, includes primary total knee arthroplasty.

It must be kept in mind that supracondylar femur fractures in the frail and elderly are inherently different from those in the younger population. In the elderly, these fractures are often caused by low energy mechanisms and have a comminuted pattern. Furthermore, as opposed to younger patients, there may have been underlying arthritis prior to the fracture. Open reduction and internal fixation in this group of patients has a high rate of fixation failure7. Additionally, a permanent decline in function after these fractures is common and Karpman et al found a one year mortality of 22% in 112 frail, elderly patients8.

Primary arthroplasty as a mode of treatment for this problem has several benefits. Firstly, any pre-existing underlying arthritis is managed. As well, arthroplasty may allow early range of motion and mobility (with varying degrees of weight bearing), which are particularly important to the elderly patient. An additional, although highly significant benefit of choosing TKA primarily is the avoidance of potential complications which may occur as a result of surgery for the conversion of failed internal fixation to TKA. These complications include arthrofibrosis, patella baja, infection and wound problems secondary to multiple procedures and incisions.

Indications
If any or all of the following are present, one should at least consider primary TKA:

  1. Underlying symptomatic arthritis of the knee.
  2. Elderly and/or frail patients, unlikely to tolerate prolonged rehabilitation or immobility.
  3. Poor quality bone in combination with a complex fracture pattern.

Technique
My preference is to manage these fractures in a delayed fashion. First the leg is splinted and the patient is mobilized to whatever degree possible for approximately 2-6 weeks. This allows the soft tissues to recover from the initial trauma and may lessen the risk of wound problems postoperatively. The delay may also allow some or all fracture fragments to unite and thus maximizes the useful bone stock available at the time of TKA. Prior to surgery I do not worry excessively about the quality of the fracture reduction as issues such as alignment and joint level will be dealt with at the time of TKA.

A standard midline incision with a medial parapatellar arthrotomy is used. The patella is not everted to avoid possible avulsion of the patellar tendon. Scarring and adhesions are taken down and an assessment of bone quality, fragment union and bone loss is made. Revision TKA techniques are then employed using revision instrumentation. Soft tissue releases are often required in order to achieve balanced flexion and extension gaps. Stems are always utilized on the femoral side but only added to the tibial side if a constrained prosthesis is needed. Metal augments are used to make-up for bony defects caused by malunion or traumatic bone loss up to 15-20mm in depth. In more severe cases, structural allograft may be needed.

In situations of extreme comminution and proximal fracture extension, the surgical technique may be complex and require allograft-implant composites or tumour-prostheses. In extreme cases I have excised the involved distal femur while retaining the soft tissue envelope including the collateral ligaments attached to the epicondyles, and performed reconstruction with a large-segment allograft and a stemmed total knee prosthesis (Figures 1 and 2). There is some evidence of acceptable success rates using this technique9.

backsteinfigure1ap.jpgbacksteinfigure1lat.jpg

Figure 1: Preoperative AP and Lateral view of complex supracondylar and proximal tibial fracture with poor bone quality.

The degree of constraint required depends on the condition of remaining collateral ligaments but in contrast to much of the literature, it is my experience that a hinge is rarely required10,11. The collaterals usually have remaining bony attachments and even when these are un-united, they can be reattached to the distal femoral host bone or allograft-implant composite. This is done using screws or heavy, nonabsorbable suture tensioning maximally at 90 degrees of flexion. The extension gap is then matched to the flexion gap based on proximal-distal placement of the femoral component.

backsteinfigure2ap.jpgbacksteinfigure2lat.jpg

Figure 2: Postoperative views.

Hybrid fixation technique is used with cemented components and cementless stems. Utmost attention is paid to the soft tissue envelope. It is critical to avoid excessive trauma to the skin or over-sized, bulky components, which place tension on the wound.

Results
There are a limited number of studies examining primary TKA for supracondylar fractures. The types of prostheses have included constrained implants12,13,14,15 and unconstrained implants16,17,18 with generally acceptable results10,12,14,13,15,16,19. Some authors have combined internal fixation methods with TKA in either a single sitting19 or in two stages.

TKA will never be the primary means of treating supracondylar fractures of the femur, however in elderly or low demand patients with poor bone quality, TKA offers a potential means of rapid mobilization and treatment of underlying joint arthritis.


References

  1. Butt M.S., Krikler S.J., Ali M.S.: Displaced fractures of the distal femur in elderly patients. J Bone Joint Surg Br 77:110, 1995
  2. Gynning J.B., Hansen D.: Treatment of distal femur fractures with intramedullary supracondylar nails in elderly patients. Injury 30:43, 1999
  3. Janzing H.M.J., Stocxkman B., Van Damme G., et al: The retrograde intramedullary nail: an alternative in the treatment of distal femur fractures in elderly? Arch Orthop Trauma Surg 118:92, 1998
  4. Marks D.S., Isbister E.S., Poster K.M: Zickel supracondylar nailing for supracondylar femoral fracturers in elderly or infirm patients. J Bone Joint Surg Br 76:596, 1994
  5. Buckwalter-Einhorn T.A., Bolander M.E., Cruess R.L., et al. Healing of the musculoskeletal tissues. In: Fractures in Adults, ed by Rockwood C, Green D. Philadelphia, JB Lippincott. 1996, 1972-2000
  6. Sanders R., Swiontkowski M., Rosen H., et al. Double plating of comminuted, unstable fractures of the distal part of the femur. J Bone Joint Surg 1991; 73: 341-346.
  7. Moore T.J., Watson T., Green S.A., Garland D.E., Chandler R.W. Complications f surgically treated supracondylar fractures of the femur. J Trauma 1987; 27:402-6.
  8. Karpman R.R., Del Mar N.B. Supracondylar femoral fractures in the frail elderly: fractures in need of treatment. Clin Orthop 1995;316:21-4
  9. Kraay M.J., Goldberg V.M., Figgie M.P., Figgie H.E. 3rd. Distal femoral replacement with allograft/prosthetic reconstruction for treatment of supracondylar fractures in patients with total knee arthroplasty. J Arthroplasty. 1992 Mar;7(1):7-16.
  10. Davila J., Malkani A., Paiso J.M. Supracondylar distal femoral nonunions treated with a megaprosthesis in elderly patients: a report of two cases. J. Orthop Trauma 2001;15:574-578.
  11. Appleton P., Moran M., Houshian S., Robinson C.M. Distal femoral fractures treated by hinged total knee replacement in elderly patients. J Bone Joint Surg Br. 2006 Aug;88(8):1065-70.
  12. Bell K.M., Johnstone A.J., Court-Brown C.M., Hughes S.P. Primary knee arthroplasty for distal femoral fractures in elderly patients. J Bone Joint Surg 9Br)1992;74-B:400-2
  13. Freedman E.L., Hak D.J., Johnson E., Eckardt J.J. Total knee replacement including a modular distal femoral component in elderly patients with acute fracture of nonunion. J Orthop Trauma 1995;9:231-7
  14. Pearse E.O., Klass B., Bendall S.P., Railton G.T. Stanmore total knee replacement versus internal fixation for supracondylar fractures of the distal femur in elderly patients. Injury 2005;36:163-8.
  15. Wolfgang G.L. Primary total knee arthroplasty for intercondylar fracture of the femur in a rheumatoid arthritic patient:a case report. Clin Orthop 1982;171:80-2.
  16. Anderson S.P., Matthews L.S., Kaufer H. Treatment of juxtarticular nonunion fractures at the knee with long-stem total knee arthroplasty. Clin Orthop 1990;260:104-9
  17. Kress K.J., Scuderi G.R., Windsor R.E., Insall J.N. Treatment of nonunions about the knee utilizing custom total knee arthroplasty with press fit intramedullary stems. J Arthoplasty 1993;849-55
  18. Yoshino N., Takai S., Watanabe Y., Fujiwara H., Ohshima Y., Hirawawa Y. Primary total knee arthroplasty for supracondylar/condylar femoral fractures in Osteoarthritic Knees. J Arthroplasty 2001; 471-75.
  19. Patterson R.H., Earll M. Repair of supracondylar femur fracture and unilateral knee replacement at the same surgery. J Orthop Trauma 1999;13:388-90

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