|Year : 2020 | Volume
| Issue : 2 | Page : 143-146
Distal femoral replacement in complex revision knee arthroplasty
Obiegbu Henry Obinna1, Katchy Amechi Uchenna2
1 Department of Orthopaedic Surgery, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Anambra State, Nigeria
2 Department of Anatomy, University of Nigeria Teaching Hospital, Enugu, Nigeria
|Date of Submission||09-Sep-2019|
|Date of Decision||29-Nov-2019|
|Date of Acceptance||15-Jan-2020|
|Date of Web Publication||11-Apr-2020|
Dr. Obiegbu Henry Obinna
Department of Orthopaedic Surgery, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Anambra State
Source of Support: None, Conflict of Interest: None
Revision knee arthroplasty is often complicated by the presence of bone loss, making the use of conventional revision implants impossible, due to inadequate bone stock and ligamentous stability. Distal femoral replacement, although traditionally was developed for salvage surgeries for bone tumours, plays an important role in revision surgeries of elderly low-demand adults with marked bone loss and ligamentous instability. Here, we report the case of a 66-year-old female, with a history of bilateral knee replacement 5 years before the presentation, who developed left knee pain, with X-ray features of failed left knee replacement. This patient had a left distal femoral replacement and successfully returned to her pre-operative function.
Keywords: Bone loss, ligamentous laxity, megaprostheses
|How to cite this article:|
Obinna OH, Uchenna KA. Distal femoral replacement in complex revision knee arthroplasty. Niger Postgrad Med J 2020;27:143-6
| Introduction|| |
Revision knee arthroplasty can be quite challenging, especially in the presence of marked bone loss. Yet, it has been estimated that in the near future, the annual number of revision total knee replacement (TKR) is expected to tripple. Patients with consecutive or multiple failed TKR commonly present with marked bone loss, making revision surgeries with augments difficult; thus limiting options needed to restore the joint function. Modular segmental endoprosthetic distal femoral replacement is a limb salvage option that is available when other options are unfeasible.
Distal femoral replacement traditionally was used solely for patients with bone or soft-tissue tumours who required substantial resection of bone, as they provided a restoration of joint function and a range of motion, and significantly decreased the rate of amputation. However, it may be used in non-tumour conditions such as revision TKR, especially in the presence of bone loss and ligamentous instability. Bone deficiency hinders implant alignment and stabilization of the bone–implant interface in revision TKR. Several methods have been advocated for the treatment of bone defects in revision TKR. They include the use of bone cement, bone cement with screw reinforcement, metal augments, impaction bone grafts and structural allografts., However, in patients with marked bone loss (with associated ligamentous instability), conventional arthroplastic and osteosynthetic methods are not sufficient for reconstruction; and resection prostheses (megaprostheses) are required to restore the joint function.
Here, we present a case of a 66-year-old female who had a revision TKR with a distal femoral megaprostheses, due to marked bone loss and accompanying ligamentous laxity.
| Case Report|| |
A 66-year-old female with a history of bilateral TKR done 5 years before the consultation, presented to the Outpatient Department of Nnamdi Azikiwe University Teaching Hospital, Nnewi, Nigeria, on the 6 February 2019, with complaints of left knee pain and associated progressively worsening deformity of 1-year duration. There were also symptoms of instability of the left knee joint. There was gross restriction of routine activities, and the patient could not walk up to 20 m without support. The deformity of the left knee joint had worsened, mostly over the past 6 months.
On examination of the left knee, there was a midline scar noted, with a 20° varus deformity, with marked laxity of both the medial and lateral collateral ligaments. X-rays done showed a failed left TKR, with displaced femoral implant and erosion of the distal femoral condyles. [Figure 1] The patient had a negative workup for infection (including a complete blood count, erythrocyte sedimentation rate and C-reactive protein). The patient was then counselled and booked for a left distal femoral replacement.
The patient was positioned supine on the operating table under spinal anesthesia. The midline incision scar was followed, and a medial parapatellar arthrotomy was done, with fibrous adhesions deep to the patella released. The implants were then exposed with dislocation of the polyethylene insert noted. The femoral component which was loose along with the dislocated polyethylene insert was easily removed. The tibial base plate which was cemented was then removed using fine osteotomes, and the cement in the medullary canal removed using burrs. The eroded femoral condyles with a complete loss of collateral ligaments were then noted [Figure 2].
|Figure 2: Eroded femoral condyles, absent collaterals, and marked bone loss|
Click here to view
The entire distal femur along with 80 mm of the distal femoral shaft which was noted to be osteoporotic was resected. [Figure 3] The tibia was not prepared further, instead, all cement mantle were removed. The femur and tibial medullary canal were reamed to accept the intramedullary stems. After trialing with an 80-mm femoral resection piece [Figure 4], wound irrigation with a pulse lavage was done.
The final implants which include a hinged distal femoral megaprosthesis along with an 80-mm femoral resection piece [Figure 5] and cemented femoral/tibial stems were then inserted. There was good patella tracking. Wound was closed over an active drain. Immediate post-operative condition was satisfactory. The estimated blood loss was 650 ml, and the patient received two units of blood intraoperatively.
There were no post-operative events, and the patient was discharged home on the 6th post-operative day. The first post-operative visit was at 2 weeks, the incision was healing well. Range of motion was from 0° to 100°. Moreover, she could ambulate independently with a Zimmer frame. Post-operative X-rays were satisfactory [Figure 6]. At a 5-week follow-up visit, she could ambulate with only walking stick, and range of motion had improved (0°–140°). At a 6-month follow-up, there were no new complaints, and she could ambulate without any walking aid.
| Discussion|| |
There has been a sustained increase in the survivorship of primary TKR worldwide. The Swedish knee arthroplasty register showed an improvement in 10-year survival from 89% for TKRs performed during 1985–1994 to 96% during 2005–2014. However, several factors including patient, implant and surgeon factors can lead to a decrease in survival rates. In a study done by Rand et al., the authors have concluded that significant risk factors for failure of TKRs include the type of implant, age and gender of the patient, diagnosis, type of fixation and design of the patella component. In a similar study done by Fehring et al. to determine the cause of early failure of TKRs, defined as failure within 5 years, they concluded that the common causes include infection (38%), instability (27%), failure of ingrowth in a porous-coated implant (13%), patellofemoral problems (8%) and wear/osteolysis (7%).
Patients requiring multiple revisions or patients with a massive bone loss with absent collateral ligament as seen in our index patient may benefit from a distal femoral replacement. The survivorship of megaprostheses has been acceptable in some studies, especially for non-tumour conditions. In a study done by Berend and Lombardi, with a mean follow-up of 46 months (24–109 months), they found an implant survivorship rate of 87%. Furthermore, in a similar study by Barrack, he reported only one intraoperative complication and one subsequent surgery without any loosening or failure noted in his group of patients. In contrast to these results, Springer et al. reported a 31% complication rate and an associated 19% rate of deep infection.
Although a distal femoral replacement is a useful revision tool, it should be reserved as a last option due to the amount of bone that must be removed, and few bailout options that remain during re-revision or failure of these devices. Kim et al. concluded in their study that these megaprostheses should not be used in patients who are young and active, even in the presence of poor bone stock due to the high likelihood of early failure and few alternative treatment options.
| Conclusion|| |
Distal femoral replacement is a viable option for the treatment of failed TKR with associated marked bone loss and ligamentous laxity, allowing return to a functional range of movement.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]