Joint Arthroplasties and Prostheses | RadioGraphics
Revision to a long-stemmed prosthesis for loosening; Loosening of Knee Prosthesis.
prosthesis loosening are used for ..
To our knowledge, there are only four other studies reporting on patients with screw disengagement from the locking mechanism most commonly due to a traumatic event9-12 or loosening from the femoral component with migration into the joint in older prosthesis versions, such as the Insall- Burstein-II constrained condylar knee prosthesis.13 Screw loosening is an uncommon complication and can lead to metallosis with backside wear and failure of the locking mechanism that may require revision total knee arthroplasty.
A 63-year-old man with syphilis and a body mass index of 19.6 kg/m2 presented with a painful swollen knee 1 month after slipping. Radiographs revealed a semi-acute depression fracture of the tibia with comparatively large defect of bone and some intra-articular loose bodies considering the pain. He had deep tendon hyporeflexia, hypo pallesthesia, disturbance of deep sensibility, and decreased protective sensation due to tabes dorsalis. Therefore, his right knee was diagnosed as a Charcot joint disease. Open reduction and internal fixation (ORIF) using a conventional non-locking plate was performed (Fig. 1). Varus deformity and delayed bone union gradually developed after the procedure. At this point, his clinical depression worsened and was accompanied by abnormal behavior. The results of the blood test TPLA 6600 (TLHA 5120 X) had deteriorated to TPLA 22000 (TPHA 10240 X). Tabes dorsalis had been treated with antibiotics (ampicillin). Despite the treatment, the patient had to be transferred to a psychiatric hospital because of aggravated neurologic manifestations. He was diagnosed with organic mental disorder caused by tabes dorsalis and was hospitalized for 2 months. 1 year later, ORIF metal removal was performed.
About 10 years after the first knee symptoms, the patient visited our hospital because of right knee pain and an abnormal gait. Clinical examination showed severe varus deformity and limitation of the range of motion. TKA was carried out with LCCK® (Zimmer Biomet, Warsaw, IN, United States) (Fig. 2). The pain subsequently subsided and the patient had an improved range of motion in the knee.4 weeks after the surgery, the patient experienced a slight pain in his right heel while walking. Radiographs did not reveal any obvious fractures (Fig. 3a). After a 1-week period of observation, plain radiographs showed an avulsion calcaneal fracture (Fig. 3b). This right calcaneus fracture was successfully treated with ORIF using two cannulated cancellous screws and a cerclage wire (Fig. 4a, b, c). 3 weeks after the surgery, partial weight bearing was permitted with a vacuum-stabilized orthosis (VACOped®, OPED, Oberlaindern, Germany) that allowed for angle adjustments at five-degree intervals. Full weight-bearing was allowed at 7 weeks after surgery. The surgical wounds healed without complications. 6 months after ORIF, bone union was eventually achieved and metal removal was performed. At the final follow-up, the patient was able to walk without difficulty. There has been no early loosening of the prosthesis so far.
MR Imaging of Knee Arthroplasty Implants | RadioGraphics
In our patient, the LCCK was implanted for severe deformity as a primary total knee arthroplasty. It remained asymptomatic for nine years without signs of radiographic osteolysis. It suddenly became symptomatic once the locking screw migrated into the knee joint. The disengagement process was probably the cause for the severe metallosis in the knee synovial tissue over an extended period. In contrast to the case reports by Rapuri et al.,9 our patient did not experience a traumatic event that may have incited the disengagement. The evidence of backside wear of the tibial polyethylene supports the theory of micromotion at the backside of the insert translating into slow loosening of the screw-thread interface. Therefore, it is important to monitor for any signs of screw loosening to prevent premature wear of the tibial insert or osteolysis around the components on an annual basis.
The use of unlinked constrained knee prosthesis has demonstrated excellent long-term outcome studies with survivorship up to 96% at 10 years.6 Reported complications with the use of a constrained knee prosthesis are similar to unconstrained knee implants and include component loosening, deep infection, tibiofemoral instability, limited range of motion, extensor mechanism problems, fractures and wound problems.8,14,15 Constrained knee implants use a pin or screw to stiffen the post to withhold the increased forces across the implant. We report on late atraumatic screw disengagement in the Zimmer (Warsaw, IN) NexGen Legacy Constrained Condylar Knee (LCCK) prosthesis.
Protocol for 1.5-T MR Imaging of Knee ..
She re-presented in February 2013 with sudden onset of acute right knee pain and clicking without a history of trauma. On physical examination the knee had active range of motion from 0 to 115 degrees and no instability but demonstrated clicking in mid-flexion. Radiographic imaging demonstrated a loosened screw with no evidence of breakage or any loosening of the tibial and femoral components .The patient underwent a medial parapatellar arthrotomy with removal of the loosened screw, implantation of a new polyethylene liner as well as a new locking screw. Intraoperatively, the screw was apparent behind the patellar tendon and the joint demonstrated extensive metallosis in the suprapatellar pouch as well as in the lateral and medial gutters . The screw was intact with minimal evidence of wear, similar to the initial polyethylene liner, which was not disengaged. There was, however, evidence of backside wear over the tibial polyethylene metal insert. We performed extensive synovectomy to remove all visible metal debris and implanted a new liner with a new locking screw. The patientâs postoperative course was uncomplicated. At two-year follow-up, she remained pain free with active range of motion from 0 to 130 degrees with no ligamentous instability and symmetric foot progression .
Constrained prostheses are used in unstable knees due to their ability to resist varus and valgus transformative forces across the knee. Aseptic Loosening of implants is caused by osteolysis. It is most significant factor limiting longevity of THA. Revision for loosening is 4x higher than next leading.
Current Concepts in Knee Replacement: ..
the prevention and management of early loosening
23/10/2014 · An interesting article from the journal RadioGraphics
Complications of Knee Prostheses
Volume 135, Issue 1
Revision knee arthroplasty due to aseptic loosening
Volume 202, Issue 1
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