it is estimated that over a million such medical procedures occur annually world - wide . however , despite the minimal rate of early complications , up to 30% of all surgeries are revised within 1014 years of initial surgery ( 1 ) . these particles are identified as one of the main causal reasons for total hip arthroplasty . the wear between primary binding surfaces of the femoral head and acetabular components in total hip replacements is considered to be the most significant source of prosthetic particles ( 2 ) . one estimation , from a study utilizing a metal on polyethylene joint , suggested the generation of hundreds of thousands of polyethylene particles during each gait cycle ( 3 ) . another study found that metal - onmetal or ceramic - on - ceramic pairings had significantly less wear on the prosthesis ( 4 ) . however , despite the variances in particle generation of different materials , osteolysis is indicated in all types of hip replacements . particle debris generated from the mechanical wear of prosthetic devices is known to alter the function of multiple cell types in the periprosthetic area , including macrophages , fibroblasts , osteoblasts , and osteoclasts ( 57 ) . the generated biologically active particles appear to provoke the formation of lytic areas through the inhibition of bone formation and increased fluid production ( 810 ) . bones are highly dynamic tissues undergoing a constant remodeling process that is regulated by a tightly - controlled balance of osteoblast and osteoclast activity . the major challenge of revision hip arthroplasty is related to osteolysis and bone loss decreasing stability of the implant . the loss of bone can surmount due to surgical bone loss from the primary operation , migration of the cup , and as mentioned previously , particle induced osteolysis ( 11 ) . consequently , the goal of revision hip surgery should be anatomical placement of the acetabular component , but this can be difficult to achieve in cases where contact between host bone and the implant is diminished . this bone loss can be managed by either filling the absent area with cement , the use of allograft bone , or by using special implants such as those constructed with trabecular metal ( 1216 ) . allograft incorporation can be implemented to reinforce the lytic area , thereby stabilizing the implant . allografts do not suffer from osteoclastic invasion and it has been shown that osteoblasts deposit osteoid across the host bone and the dead graft ( 17 ) . this union results in an increased mechanical resistance that is indicated by increased radiological density throughout the graft ( 18 ) . the structure of trabecular metal resembles bone and approximates its physical and mechanical properties more closely than other prosthetic materials . the highly porous trabecular configuration is conducive to bone ingrowth , facilitating rapid and extensive tissue infiltration resulting in strong implant attachment ( 19 ) . trabecular metal consists of interconnecting pores resulting in a crystalline micro - textured biomaterial that is 80% porous . this allows for greater tissue ingrowth ( 23 fold higher compared to conventional porous coatings ) with approximately double the interface shear strength ( 19 ) . in hip arthroplasties , porous trabecular metal facilitates bone ingrowth and fixation of the device ; multiple studies have shown that most replacements can be reconstructed with an uncemented trabecular hemispherical cup with screws with or without morselized bone graft ( 2022 ) . because of their porous surface and mechanical properties trabecular metal cups provide a promising approach for offering a better environment for bone graft remodeling ( 23 ) . in this case study we detail the use of a trabecular metal cup to halt the migration of the component into the acetabulum and promote greater fixation and bone ingrowth . additionally , we show the use of a tibial allograft coupled with bone chips and cement to cover and support a lytic cyst in the proximal femur , distal to the greater trochanter . a 73 year old man presented with instability in the left hip , 17 years after bilateral hip arthroplasty was completed . the original replacement was a ceramic head on a polyethylene lined acetabular component . still working full time and an active individual , instability and sharp pain presented down the lateral aspect of his left leg during jarring actions . during physical examination , good range of motion and gait was displayed in both hips , although pain was produced during forced external rotation of the left hip . x - rays showed significant osteolysis of the proximal femur , distal to the greater trochanter of his left hip ( figure 1 ) . despite the bone loss , the stem appeared to still be solid . it was anticipated that the progressive wear of the polyethylene cup would induce small particle disease involving the greater and lesser trochanter areas . comparison to the current x - rays ( figure 1 ) revealed that the particle disease had expanded and significantly increased the endosteal lytic zone , it was also evident that the ceramic head had penetrated deeper into the acetabulum . to avoid impending femoral fracture or avulsion of the greater trochanter from lytic bone loss , revision of the left hip was scheduled . since the stem had good fixation , the choice was made to leave it in place and use a bone graft to support the lucent area distal to the greater trochanter . a tibial allograft was used to secure the femoral component and stabilize the lytic area . the allograft was irradiated with 2.5 mrad ( 25,000 gy ) in the hospital bone bank , accrediated by the american association of tissue banks , and consequently stored at 70 degrees celsius . the approximate allograft size was templated preoperatively and a longer graft ordered to account for any intraoperative adjustments . the allograft was only brought into the operating room after possible infection of the to - be - revised hip was ruled out . in order to reduce operative time , the allograft was prepared on a separate table by members of the surgical team while the revision was initiated . the femoral component had good fixation so additional bone ingrowth was not a major concern . thus , cement was used to fill in the lytic area and provide additional structural support . polymethylmethacrylate bone cement has been known to strengthen allograft bone , impair resorbtion , and allow for the delivery of antibiotics ( 24 ) . cement was not used between the allograft and the host bone , only in the lytic area between the allograft and the implant , so as not to impair healing at the host - donor interface . additionally , morselized bone from the allograft was used between contact sites of host and donor bone in an effort to increase bone ingrowth . operative visualization confirmed the cup had protruded into the acetabulum and wear on the polyethylene lining was evident , necessitating its replacement . a zimmer trilogy acetabular system was selected to replace the acetabular component , consisting of a metal shell , polyethylene liner , and screws . the shell , made from tivanium ti-6al-4v alloy , is pourous to allow for fixation with tivanium alloy cortical screws . in this case , three 6.5 mm screws of lengths 25 , 30 , and 35 mm were used to secure the cup into the acetabulum . the original cup was uncemented , 56 mm in size and was replaced with a similar 56 mm trabecular metal cup . the porous trabecular metal serves to facilitate bone ingrowth and increased fixation of the arthrography . bone chips from the excess allograft were also used to fill in the protruded acetabulum from the original implant . immediately following the surgery the patient was taken to radiology for post - operative x - rays ( figure 2 ) . revision of the acetabular component with a trabecular metal cup was then visualized and correct placement within the acetabulum was confirmed . the original femoral component was also visualized , shown reinforced with a well placed tibial allograft . revision cases are usually rehabilitated more conservatively than primary replacements , as was the case here . this patient was treated with additional care due to the use of allograft bone to stabilize the femoral component . during the first week post - op , our patient was encouraged to begin range - of - motion ankle exercises and moving with a walker / assistance 5 to 10 feet the first day after surgery which was done with success . throughout the first week , aided walking was extended to 2545 feet and stair - climbing with crutches was introduced after day 5 . stair climbing and other motions that bend the knee must be watched carefully as for the first 3 months the patient is advised not to bend their knee past 90 degrees . additional x - rays were taken after 3 months to confirm fixation of the aetabular component and evaluate the success of the tibial allograft over the osteolytic area in the proximal femur ( figure 3 ) . the acetabular component appeared to be well placed and the observed migration into the acetabulum was halted . the tibial allograft , marked with a white arrow , remains in place supporting the area of osteolysis . the level of transparency had reduced significantly after successful cleaning of the cyst and filling the lytic zone with biocompatible polymethylmethacrylate bone cement . physical examination was completed at the same time as x - rays to ensure the patient had continued with the rehabilitation program and was continuing to make significant progress . ambulation , range of motion , and functionality were all observed and were progressing well . the patient is now fully recovered , ambulating and functioning without pain or discomfort . for reasons including particle disease , revision of total hip replacements generally occur upon indication of a painful loose prosthesis . davis et al . ( 25 ) used the western ontario and mcmaster universities osteoarthritis ( womac ) questionnaire to grade pain and function pre- and 2-year - postoperatively . the study reported that a higher pain level and number of comorbidities before the surgery predicted poorer outcomes at 24 month post - surgical follow - up . patients with better preoperative womac pain and function scores had better scores postoperatively , suggesting the benefit of performing total hip revision not only to relieve current symptoms , but to reduce the chance that pain and function will worsen while waiting for surgery . in this case , loosening was first noticed by the patient through instability and loss of gait control and later confirmed through radiography . if surgery had waited until higher levels of pain were expressed to maximize the life of the original device , more serious complications may have occurred . by performing the revision more complicated surgeries with worse outcomes , potentially for failure due to fracture , the use of allograft is shown as an effective way to support components threatened with osteolysis . donor bone in combination with biocompatible cement can greatly reduce the potential for injury and pain due to lytic bone loss .