T he LCS or New Jersey Knee (DePuy Orthopaedics Inc, Warsaw, Ind) prosthesis is a total condylar, low contact stress, mobile bearing prosthesis, which allows reten- tion or excision of the posterior cruciate ligament. The cemented version has a sandblasted finish on cobalt-chrome- molybdenum metallic surface for cement fixation, whereas the cementless version uses Porocoat sintered beads (DePuy) for bone ingrowth (Figure 1). This article highlights a previously unreported cause of knee pain after arthroplasty, and emphasizes the impor- tance of a surgeon’s familiarity with implant components. This is particularly relevant to the low-volume arthroplasty surgeon who is more susceptible to com- plications. 1 CASE STUDY A 58-year-old man presented with an LCS knee replacement preformed 1 year prior to presentation. He reported continuous knee pain on weight bearing, which was initially noted 5 weeks postoperatively. The postopera- tive regimen allowed partial weight bearing with crutches for 6 weeks with no wound heal- ing problems. A stable knee with a good range of movement (0°-105°) was achieved. The patient reported diffuse knee pain, but tender- ness was elicited on palpating the proximal tibial rim. Radiographs obtained 5 months after the index procedure showed the tibial component had subsided 3-4 mm posteriorly in a slightly varus position (Figure 2). Blood indices including white blood cell differential count, erythrocyte sedimentation rate, and C- reactive protein were normal. Technetium bone scan performed 6 months postoperatively showed increased uptake at the tibial interface compared to the femoral interface. A diagnostic intra-articular injection of 2% lidocaine provided temporary pain relief. Because component loosening was suspected, the knee was explored. The operative findings revealed a loose tib- ial component. The femoral and patellar com- ponents were retained more firmly but still removed easily. All components had textured surfaces and had not been cemented in place. A thin fibrous membrane had formed at the bone- implant interface and bony integration was not present. Intraoperative cultures were negative and histology of the membrane showed an absence of neutrophils, ruling out infection as a cause. Long stem revision components were cemented in situ. The patient made an unevent- ful recovery and remains pain-free. APRIL 2004 | Volume 27 • Number 4 417 ■ Case Report Uncemented Application of Cemented LCS Knee Prosthesis Leading to Knee Pain WILLIAM J. GAINE, FRCSORTH; ASLAM MOHAMMED, FRCSORTH From the Hip Centre, Wrightington Hospital, Lancashire, United Kingdom. Reprint requests: William J. Gaine, FRCSOrth, Kilrea, Strandhill Rd, Sligo, Ireland. Figure 1: Textured LCS tibial component (left) and porous coated tibial component (right). Figure 2: Medial subsidence of textured tibial component with absence of cement. 1 2 4gaine.qxd 4/6/04 3:54 PM Page 417