Clin Geriatr Med 22 (2006) 515–533

Hip and Knee Arthroplastyin the Geriatric Population

Selvon F. St. Clair, MD, PhDa, Carlos Higuera, MDa,Viktor Krebs, MDa, Nabil A. Tadross, MDb,Jerrod Dumpe, BAc, Wael K. Barsoum, MDa,*

aDepartment of Orthopaedic Surgery, The Cleveland Clinic Foundation,

9500 Euclid Avenue Cleveland, OH 44195, USAbDepartment of Internal Medicine, The Cleveland Clinic Foundation,

9500 Euclid Avenue Cleveland, OH 44195, USAcMedical College of Georgia, 1120 15th Street, Augusta, GA 30912, USA

Growth of the geriatric population and the role of total joint replacement

Senior citizens are the fastest growing subset of the American population.In 2000, there were 35 million people over age 65 [1]. It is estimated that bythe year 2030 the geriatric population will represent approximately 20% ofthe American population or approximately 70 million people [1]. The rapidand persistent increase in the elderly population will affect the use and costsof health care in the United States significantly [2]. This will be most apparentin the treatment of disease and injuries of the musculoskeletal system. Thelatter is because more than 80% of the geriatric population has musculoskel-etal complaints requiring a physician encounter and some form of treatment[3,4]. In particular, severe progressive osteoarthritis (OA) of the hip and kneeaccounts for approximately 40% to 60% of musculoskeletal complaints inthe elderly [3,4]. Further, hip fractures and tumor metastasis to proximaland distal femur or proximal tibia frequently are seen in older people. Severeend-stage OA of the hip and knee, femoral neck fractures, and pathologicconditions affecting proximal and distal femur and the proximal tibia usuallyresult in joint replacement surgery. Approximately 68% of total hip arthro-plasties (THA) and 74% of total knee arthroplasties (TKA) are performedon people over age 65 [3]. With the current growth rate of the geriatric

* Corresponding author. Department of Orthopaedic Surgery (A41), The Cleveland

Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195.

E-mail address: barsouw@ccf.org (W.K. Barsoum).

0749-0690/06/$ - see front matter � 2006 Elsevier Inc. All rights reserved.

doi:10.1016/j.cger.2006.04.004 geriatric.theclinics.com

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population, by the year 2030, there will be an approximate 40% to 80% in-crease in total joint replacement surgery performed in older patients [1,4].

Since their introduction in the late 1960s in the United Kingdom as high-risk, last-resort procedures, hip and knee arthroplasty procedures haveundergone a rapid evolution. In 1996, more than 607,000 knee and hipreplacements were performed in the United States [2]. Patients who haveknee or hip joint arthroplasty attain improved mobility and significantimprovements in quality of life, with postoperative quality of life often equalto or exceeding the population norm. This translates into retained indepen-dence and self-care and decreased health care costs [5]. THA and TKAsurgeries are among the most successful interventions available to the geri-atric population, as measured by the Medical Outcomes Study 36-ItemShort-Form Health Survey (SF-36) in terms of improvement in quality-of-life years gained [6].

Osteoarthritis of the hip and knee joints

OA is a chronic widespread form of arthritis that affects all joint struc-tures and commonly is manifested in hip and knee. Except for traumatic ar-thritis, which can occur at any age after an injury, the prevalence of OAincreases with age. OA is slightly more common in knees compared withhips. Its onset is insidious but progressive, resulting in significant painand disability, often leading to deterioration in function and loss of indepen-dence. OA of the hip and knee is among the top causes of pain and physicaldisability in community-dwelling adults [7]. Further, OA is a disease of ag-ing cartilage. Although the exact pathophysiology of OA is yet to be delin-eated completely, the etiology of OA likely is multifactorial, including riskfactors, such as genetic origins, microtrauma, increased cytokine activity,lack of nutrients (eg, antioxidants), and obesity.

The diagnosis of OA of the knee and hip is made clinically and radio-graphically. Clinically, patients who have OA have symptoms of pain-related activity that decrease with rest. In knee OA, other signs andsymptoms include knee swelling secondary to effusion, crepitation and sub-jective locking and sensation of unsteadiness, and angular deformity of thehip and knee that invariably results in gait abnormality secondary to de-creased quadriceps strength and joint flexibility [8–10]. The latter frequentlyis seen in severe end-stage OA. Older patients commonly require walking as-sist devices for ambulation or sometimes are wheelchair dependent. The ul-timate and sometimes devastating end result of OA is debilitating pain andloss of independent functioning (ie, low SF-36 scores [11]), manifested by aninability to carry out activities of daily living.

The psychologic secondary morbidity resulting from functional impair-ment is substantial. In one study, 200 patients completed a questionnaireabout functional disability related to OA and mood (anxiety and depres-sion). There was an 8.3% prevalence of depression in this population and

517ARTHROPLASTY IN THE GERIATRIC POPULATION

a 24.4% prevalence of anxiety. Additionally, it was found that after surgery,the level of independent living, without assistance, greatly improved the psy-chologic well-being of these patients [12].

Clinically, the main presentation of OA is pain. Depending on the sever-ity of the disease, effusion, crepitation, and angular deformity of the affectedjoints are not uncommon. As a result, patients typically present with an ant-algic gait. The clinical manifestations of OA of the hip correlate closely withits radiographic findings. The plain radiograph remains the primary objec-tive diagnostic modality (Fig. 1). There are five cardinal findings of OAon radiograph: asymmetric loss of cartilage resulting in joint space narrow-ing, subchondral bone cysts, osteophytosis, bony eburnation, and subchon-dral bone sclerosis. The plain films also can be used to grade the severity ofOA. It is widely accepted that there are four stages or grades of OA, graded1 to 4, ranging from less to more severe. Grade 1 is mild OA of hip or kneewith preservation of joint space. At the other extreme, grade 4 is OA withbone on bone articulation. At this stage, valgus or varus angular deformityis not uncommon. Finally, the severity of OA dictates its medical and or sur-gical management.

Nonsurgical or medical management of OA is geared at pain relief. Ini-tially, the most conservative treatment is a low dose of acetaminophen usu-ally combined with a trial of physiotherapy [13]. The latter increases bonedensity and muscle strength [14,15]. Second-line analgesia involves nonste-roidal anti-inflammatory drugs (NSAIDs), which are used either continu-ously or on an as-needed basis. NSAIDs used in the elderly must bemonitored closely, however, because of the associated high morbidity andpotential mortality profile of these drugs. It is reported that 20% to 30%of all hospitalizations and deaths secondary to peptic ulcer disease in the el-derly are indirectly or directly related to NSAIDs use [16]. Alternatively,selective cyclooxygenase-2-specific inhibitors can be used if there are

Fig. 1. (A) Bilateral knees anteroposterior x-ray view. (B) Left knee lateral x-ray view.

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significant risk factors for upper-gastrointestinal complications. Intra-articu-lar therapies, including steroids and hyaluronic acid–like products, are usedif pain relief is inadequate and there are effusions or obvious inflammatorysigns [16,17]. Attention also must be paid to nonpharmacologic measures,such as patient education, weight loss, and exercise [18]. Because of the pro-gressive and destructive natural course of OA, however, most affected indi-viduals require surgery, usually in the form of joint replacement, fordefinitive pain control and functional restoration.

History of the surgical management of joint disorders

The crippling effects of joint arthritides have been present in humanssince they evolved to walking upright. The biomechanical stresses placedon the skeletal framework by an upright posture, weight bearing, and gaitare evident in skeletal remains unearthed at excavations dating to medievalSaxon and Roman times. The evidence of articular disease is etched clearlyinto these remains. Just as the human race has evolved and developed thesediseases of the joints, so has the field of orthopedics evolved to develop andimplement ways to correct these arthritides.

The first large-scale advance in treating joint arthritides came in the early1800s. These operative advances were made possible because of discoveries inbasic physiology. Through anatomic dissection of cadavers and applicationof the their findings to human models, early surgeons began to understandfully the physiology of skeletal tissues and how these tissues effected the bio-mechanical processes taking place in skeletal support and ambulation.

The initial paradigm shift in dealing with joint disease took place in Liv-erpool, England, in the early 1800s. Henry Park was the first surgeon tomove from the norm of amputation for injury and joint disease to total jointexcision with pseudarthrosis formation. Dr. Park’s method of joint correc-tion was slow to gain acceptance because of several factors taking placeacross Europe and the Americas. The first was the wars taking place in Eu-rope that produced patients for whom amputation was the fastest means ofproviding life-saving care. Surgeons of this time were valued for their surgi-cal speed as much as for their surgical prowess, and Dr. Parks’ joint excisionwas not a fast surgery compared with amputation. The other daunting ob-stacle was that Dr. Park was practicing in the preanesthesia era.

The next leap forward in joint disease came toward the end of the 1800s.In 1885 in Lyon, France, Leopold Ollier, whom many have labeled, ‘‘TheFather of Orthopedic Surgery,’’ described the concept of interpositional ar-throplasty. His initial attempts at remedying arthritides used adipose tissueinterpositioned between the offending bones. The downfall to his procedurewas that he did not affix the adipose to the subjacent bone, so it often didnot stay in place and provide the cushioning it was intended to. Despitethis procedure largely being ineffective, it opened the door of belief thatmaterials might be inserted into the joint space to provide relief. After

519ARTHROPLASTY IN THE GERIATRIC POPULATION

Dr. Ollier’s initial attempts, surgeons all over Europe began experimentingwith different interpositional materials, none more than Czech surgeon, Vite-zlav Chlumsky, who tried muscle, celluloid, silver plates, rubber struts, mag-nesium, zinc, glass, pyres, decalcified bone, andwax, all withoutmuch success.

Interpositional arthroplasty experimentation continued into the 1900sbut never provided great success until the 1910s, when Sir Robert Jonesshowed in a 21-year follow-up report that several of his patients in whomhe had placed gold foil over the reconstructed femoral heads retained effec-tive motion and stability. This finding provided support that interpositionalarthroplasty was feasible and helped boost joint surgery to its next phase.

In 1932, American surgeon, Marius Smith-Petersen, described the firstmold prosthesis interposition through a new anterior approach to the hip.Smith-Petersen designed a glass mold that was placed between the femoralhead and the acetabulum. His reasoning was that this mold would facilitatehealing of the disrupted and destroyed joint membrane by providing a surfacefor newmembrane to adhere to.Many of themolds broke and, despite findingevidence of newmembrane formation on the glass during revision surgery, pa-tient complaints about continued pain caused Smith-Petersen to abandon theglass mold. Smith-Petersenwent on to trymany other possiblematerials but itwas not until 1937 when a material was found that enabled orthopedists toachieve the first long-term predictable results in interpositional hip arthro-plasty. This material, Vitallium, had the ability to withstand wear, stay ina more fixed position, not break, and not cause patients pain and discomfort.

At the same time that interpositional arthroplasty was striding forwardwith various experimental materials, prosthetic hip arthroplasty also wastaking shape and gaining more notoriety. The first to really pioneer this sur-gery were the Judet brothers from Paris, France. Initially, they used anacrylic prosthesis, in 1948, which failed miserably because of a high wearrate but ushered in a new idea of belief that the offending joint could be re-moved and replaced. Many orthopedists began experimenting with differentapproaches to the hip, different materials and constructs, and different de-signs. Notable surgeons, such as Girdlestone, Thompson, and AustinMoore,designed prostheses that met with variable success and duration of use.The stage was set, however, for Sir John Charnley to make his revolutionaryadvances and usher in the age of THA [19].

Charnley began his refinement of hip arthroplasty with a better under-standing of the hip. He delved more deeply into its function, its attachments,and its biomechanics. His research and understanding led to the establish-ment of low-friction arthroplasty. This technique contributed multipleadvancements that had not been seen until this time. The name of thetechnique comes from Charnley’s replacing the arthritic hip socket witha better wearing, high-density polyethylene cup and replacing the femoralhead with a Moore-Thompson–type metal prosthesis with a smaller head di-ameter, thus reducing the friction present in the metal-on-metal implants. Heintroduced the bone cement, methylmethacrylate, to stabilize the prostheses

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in the bone, thereby lessening the risk for implant loosening, which had beenthe main reason for hip replacement failure. He introduced clean-airoperating techniques to reduce bacteriologic contamination during surgery,reducing infection rates. His advances in biomechanics, materials, instrumen-tation, and procedures garnered Charnley the highest accolades [20].

Joint replacement surgery for osteoarthritis of the hip and knee

A large majority of older patients who have severe symptomatic OAchoose to undergo THA or TKA for long-term pain relief, improvementof function, and quality of life. This decision is supported by many studiesthat show excellent outcomes after joint replacement surgery. Currently,there is a general trend in THA and TKA to be less invasive with the surgi-cal approaches, thereby minimizing soft tissue trauma, blood loss, and op-erative time. Patients who were at least 75 years old at the time of surgeryimproved their preoperative scores on the SF-36 to levels comparable toan age-matched nonsurgical group [6]. Another study demonstrates thatelective THA and TKA in patients at least 80 years old had markedly im-proved postoperative knee and hip scores comparable to younger patients[21]. Therefore, age alone is not a barrier to hip and knee arthroplasty sur-gery in the elderly, because postoperative outcomes mostly are correlatedwith preoperative comorbidities [4]. Thus, preoperative planning becomesan important and integral part of the planning for THA and TKA surgery.

Preoperative assessment for patients scheduled to undergo THA andTKA surgery determines patient comorbidities and risk assessment profile.The general goal is to identify and treat any conditions previously undiag-nosed and to optimize known medical problems to reduce preoperativerisk. Even with thorough preoperative optimization, there remain severalabsolute contraindications to THA and TKA. These include active systemicand skin infection, open wounds, neuropathic joints, and documented ad-verse reaction to anesthesia. During this process, consent for the procedureusually is obtained. The risks, benefits, and alternatives to surgery are dis-cussed in great detail with the patients and families (especially in cases wherepatients cannot give consent because of cognitive impairment), with specificmention made of the incidence of the known and documented perioperativecomplications. Some of these complications include deep periprosthetic in-fection, early and late dislocation, deep vein thrombosis (DVT), pulmonaryembolus, and death. For patients over 80 years old, the added risks of myo-cardial infarctions and stroke are emphasized [22].

Total hip arthroplasty

THA was developed in the 1960s for the treatment of hip OA in elderlypatients. Since then, THA has progressed greatly and now is considered thestandard of care for severe end-stage OA of the hip in elderly patients. THA

521ARTHROPLASTY IN THE GERIATRIC POPULATION

alleviates pain and improves physical activity significantly, at the same timere-establishing independence and a heightened quality of life [4].

THA typically takes approximately 1.5 hours to complete and involvesfixation of the acetabular and femoral components. The actual techniqueused to fix the components may vary depending on the bone quality, train-ing of the surgeons, and implant designs. Similarly, the surgical approach isheavily surgeon dependent. Cemented and cementless fixation techniquesare used for THA components fixation. Although there are many studiesthat show good to excellent outcomes in older patients when cementingtechniques are used for component fixation [23,24], recently there is a trendtoward cementless fixation technique for the acetabular and femoral compo-nents using porous coated implants, reducing the adverse effects of ce-mented fixation. The cementless fixation relies on bony ingrowth, which isof sufficient quantity in the elderly to provide stable long-term fixation.This is supported by clinical and cadaveric investigations. Lester and col-leagues demonstrate in an autopsy study that cementless femoral compo-nent were well fixed and stable for an average of 22 months in elderlypatients [25]. Konstantoulakis and coworkers show that uncemented hip ar-throplasties in patients ages 65 and older had no signs of discernable subsi-dence or osteolysis after 4 years of follow-up [26].

There are several different bearing surfaces used in older patients undergo-ing THA. The most widely used is highly cross-linked polyethylene witha metal femoral head. The longevity of this construct depends on the wearrate of the polyethylene [27]. In geriatric low-demand patients, this hybrid-bearing surface is quite successful [28,29]. Another bearing surface makinga resurgence is metal on metal. The newer generation metal-on-mental bear-ing surface has a significantly better wear profile compared with conventionalmetal-on-polyethylene surface [30,31]. This surface commonly is used inolder patients who lead a relatively more physically active lifestyle. Lastly, ce-ramic-on-ceramic or ceramic-on-polyethylene rarely is used in older patientsin the United States and commonly is reserved for younger, high-demand pa-tients. Despite the actual technique or the articulating surface used in THA,this remains a successful operation for elderly patients who have severe OA ofthe hip. Survival analysis suggests that 95% of traditional THA interventionslast for 15 years and 85% to 90% for more than 20 years [23,24].

Total knee arthroplasty

The development of TKA for the treatment of knee pathology lagged be-hind that of THA and was considered an unsuccessful operation with manycomplications in the 1970s and early 1980s. With newer model designs pay-ing strict adherence to knee kinematics, however, TKA has become a suc-cessful operation, with survivorship of 91% at 10 years, 84% at 15 years,and 78% at 20 years [32]. It is embraced as the treatment of choice in pa-tients over age 55 who have progressive and painful OA and who have failed

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nonsurgical and less invasive treatments. The benefits after TKA aremarked improvement in all facets of health, including mobility; well-beingand emotional status; less social isolation; and reliable pain relief [33].The benefits are noticeable in patients over 70 years of age. Birdsall andcolleagues show that after TKA, patients 80 years and older had improvedpain, emotional status, sleep, and physical mobility [34]. Another studydemonstrates that patients over age 85 had similar outcomes [35].

The surgical goals of TKA are to create a kinematically stable, solidlyfixed, and well functioning knee. This is achieved by good fixation tech-niques, soft tissue balancing, and restoration of the mechanical axis. Lackof attention to any aspect of these three important steps leads to an imper-fect knee that may require revision. Although cementless fixation techniquesusing porous coated pegs, stems, or screws are used, methylmethacrylate ce-ment for component fixation is used most commonly in elderly patients. It isdebatable whether or not retention, sacrifice, or substitution of the posteriorcruciate ligament leads to better outcomes of primary TKA [36]. At the au-thors’ institution, most surgeons retain the posterior cruciate ligament if it isintact at the time of surgery. It remains controversial whether or not the pa-tella should be resurfaced during TKA [37]. Only recently has it become rou-tine by most surgeons in the United States to resurface it as part of the initialTKA procedure. A few studies demonstrate increased incidence of anteriorknee pain after TKA in patients who have unresurfaced patellae, which arealleviated with second-stage resurfacing [37]. Alternatively, there is demon-strable adverse impact on resurfaced patellae as it pertains to patella frac-ture or component loosening [38]. Additionally, the benefits of patellarresurfacing are manifested in better stair-climbing ability and improvedoverall function [37,38]. At the authors’ institution, it is common practiceto resurface the patella during the primary TKA procedure.

Complications of hip and knee arthroplasty surgery

Despite the best efforts in component design, patient selection, and pre-operative and postoperative precautions in TKA and THA, complicationsoccur. Intraoperative complications during routine THA and TKA arerare. Such occurrences include fat embolism, nerve injury (sciatic or com-mon peroneal nerve) with resultant foot drop, vascular injury, and fractures.Complications that primary care providers typically encounter after totalhip and knee surgery are infections, dislocation, and thromboembolism,whereas more severe complications, such as periprosthetic fractures, usuallyfind their way to the emergency department.

Infection

Deep periprosthetic infection remains a challenging and potentially dev-astating complication of THA and TKA surgery. It is one of the leading

523ARTHROPLASTY IN THE GERIATRIC POPULATION

causes of reoperation after joint arthroplasty. Management of deep peri-prosthetic infections relies heavily on prevention. Prophylactic antibioticgiven within 1 hour of skin incision and continued for 24 hours after surgeryhas reduced the incidence of infection greatly in primary joint replacementsto 1% to 4% [39–41]. Other preventative measures taken to reduce the in-cidence of deep periprosthetic infections include reconstructing operatingrooms with clean laminar airflow system, draping with iodine adhesive pro-tective plastic, thorough cleaning of the operative sites with iodine or provi-dine and alcohol, effective sterilization of instruments and proper conductwith strictest adherence of operating room etiquette by all personnel [41].

The main bacterium responsible for deep periprosthetic infection is Staph-ylococcus aureus, which may be a result of direct inoculation or hematoge-nous seeding [41]. Patients commonly present with a brief history of pain,swelling, and erythema of the surgical wound. Successful treatment of deepperiprosthetic infections is a work in progress but involves comprehensiveantibiotic coverage and debridement, prosthesis revision with 1- or 2-stagedreimplantation, or resection arthroplasty with or without concomitantarthrodesis [42,43]. Antibiotic treatment alone rarely is recommended fordeep-seeded sepsis around the prosthesis and typically is reserved for supra-fascial wound infections with susceptible organisms. It is now accepted widelyin the United States that deep periprosthetic infection within 2 to 4 weeks ofinitial joint arthroplasty or signs of acute infection in joint arthroplastyperformed several years ago without prior infection can be treated withdebridement plus polyethylene exchange coupled with a 6-week course of in-travenous antibiotic therapy [42,44]. The success of this approach dependson several factors, which include susceptibility of the isolated organisms, sta-bility of the implants, patient age and comorbidities, and the extent of soft-tissue injury. More than 70% of deep periprosthetic infections can be treatedusing this approach [42]. The effectiveness of these techniques in olderpatients has not been established. Most surgeons in the authors’ institutionfavor the 2-staged approach with implantation of a temporary antibiotic im-pregnated spacer for 6 weeks along with intravenous antibiotic before bring-ing patients back for definitive reimplantation of a new prosthesis (Fig. 2).Finally, in rare instances, leg amputation after failed multiple knee revisionsurgeries for chronic recalcitrant infection is reported in the literature [45].

Dislocation after total hip arthroplasty

After implant loosening, dislocation is the second leading cause of revisionhip surgery and is a common early complication of THA [46]. The incidenceof hip dislocation ranges from 0.6% to 7% [47]. The cumulative risk for anydislocation is reported as 2.2% at 1 year, 3.8% at 10 years, and 6% at 10 years[48]. Many factors are associated with increased rate of dislocation, includingsurgeon experience, implant design and positioning, surgical approach, tro-chanteric nonunion, obesity, alcoholism, and previous revision surgery [47].

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During the past few years, more emphasis has been placed on implantdesign and positioning because of its impact on reducing the rate of dis-location. The end goal is to increase range of motion within patientphysiologic arc of motion without causing impingement, which can resultin instability and increase dislocation rate. Computer-generated data provethat the optimal cup position should be 45� to 55� abduction and 10� to 20�

anteversion to reduce the risk for impingement and dislocation [49]. Surgicalapproach also influences the dislocation rate. In one study, Morrey reportsthat the posterior approach had the highest dislocation rate, 5.8%, com-pared with anterior 2.3% and lateral 3.1% [50].

Treatment of the first dislocation is done predominantly via closed reduc-tion under anesthesia in either the emergency department or the operatingroom setting. Revision hip arthroplasty for dislocation is performed mainlyafter multiple dislocations and after the first dislocation, only if the com-ponents are malpositioned significantly, resulting in instability after closedreduction (Fig 3).

Periprosthetic fractures after total hip and knee arthroplasty

The timing of periprosthetic fracture around the hip and knee is unpre-dictable and may occur either intraoperatively with insertion of the prosthe-sis or many years later. The incidence of periprosthetic fractures after THAand TKA is 2.5% and less than 2%, respectively [51]. The two main causesof periprosthetic fractures after THA and TKA are due to either trauma orloosening secondary to wear debris–induced osteolysis or osteoporosis [51–53]. Fortunately, intraoperative periprosthetic fractures are rare, although

Fig. 2. (A) Anteroposterior (AP) x-ray view of infected right knee. (B) AP x-ray view after first

stage of TKA revision resulting from infection. The knee prosthesis was removed and an anti-

biotic impregnated cement spacer was implanted. (C) AP x-ray view after second-stage of TKA

revision resulting from infection 6 weeks after the first revision. New revision prosthesis was

implanted.

525ARTHROPLASTY IN THE GERIATRIC POPULATION

the incidence is more common among cementless versus cemented hip andknee prosthetic components [53].

Treatment of periprosthetic fractures around the hip depends on the lo-cation of the fracture, the stability of the fixed components, and the qualityof bone stock. For proximal fractures with well-fixed components (for ex-ample, greater trochanteric fractures), cerclage cables with cage usuallyare performed. Management of distal fractures beyond the lesser trochanterinvariably is with open reduction and internal fixation. The specific con-struct used (cable plate fixation; cerclage cables with strut allografts withcomponent retention; or femoral component revision with longer stem afterreduction of the fracture with cerclage cables, cable plate, or strut allografts)depends on whether or not the stem is well fixed or loose [54].

Periprosthetic fracture after TKA occurs primarily around the femoralcomponent [55]. Treatment is a balance between maximizing alignmentand stability while restoring early range of motion to reduce stiffness. De-pending on the fracture location and degree of displacement, bone quality,and stability of the fixed components, many treatment options are availableto the surgeon. Poor surgical candidates who have fractures around the kneeafter TKA may be treated conservatively with knowledge that the outcomewill be a malaligned and stiff knee [56]. Open reduction and internal fixationis performed on patients who are acceptable surgical candidates who havedisplaced fractures but stably fixed components. These are reduced eitherwith fixed-angle devices, such as locked condylar plates, especially in pa-tients who have osteoporotic bone, or retrograde intramedullary nailingvia transarticular approach through the implant that has an open intercon-dylar notch. In cases of implants that are not well fixed, revision arthro-plasty is the treatment of choice with bone defects reconstructed witheither allograft or augmenting metal wedges [55,56].

The recognition of risk factors for periprosthetic fractures is vitally im-portant for its prevention and relies on surgeon and patient. Factors thatcan be controlled by surgeons include adequate surgical exposure during

Fig. 3. (A) Anteroposterior (AP) x-ray view of pelvis showing dislocation of right hip prosthe-

sis. (B) AP x-ray view of pelvis after right THA revision.

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the procedure; careful and precise preparation of the bone surfaces with thegoal of alleviating maneuvers that create stress risers; careful and controlledinsertions of cementless implants, especially in patients who have poor bonestock; and performing revision surgeries electively on patients who haveradiographic evidence of failed implants. Alternatively, patients must behighly motivated and are obligated to be compliant with timely follow-upappointments; must refrain from risky activities after hip and knee arthro-plasty; and must continue medical treatments for underlying comorbiditiesthat may put them at an increased risk for periprosthetic fractures.

Thromboembolism

Venous thromboembolismdDVT and pulmonary embolism (PE)disperhaps the most common complication after THA and TKA. Without ef-fective postoperative prophylaxis, thromboembolism is reported to occur inmore than 50% of patients who undergo THA or TKA. It is approximately3 times more likely in patients who have TKA compared with THA [57]. Pa-tients who are obese and 65 years or older particularly are at risk for havingadverse thromboembolic events after THA, with a mortality rate of 1.7%.[58]. Similarly, the risk for fatal PE after TKA without thromboprophylaxisis 0.4% [59]. DVT alone causes significant morbidity in older patients as itleads to chronic venous insufficiency or post-thrombotic syndrome. There isa high incidence of post-thrombotic syndrome in patients after THA andTKA, approaching almost 100% at 10 years after the first DVT [60].

The literature supports the effectiveness of thromboprophylaxis in reduc-ing the incidence of DVT and fatal PE. Although uncertainty surrounds thechoice of the optimal agents used to prevent and treat existing thromboem-bolism, the prevalence of DVTs after treatment ranges from 15% to 25%after THA and 35% to 50% after TKA [57] and is reduced by preventivetreatments. Modalities used to reduce the prevalence of thromboembo-lism fall in two major categoriesdmechanical and pharmacologic. The pre-dominant mechanical modality used is the external pneumatic compressiondevices, which increase venous return, decrease stasis, and enhancefibrinolysis [61]. Used alone, mechanical devices are not shown more effec-tive than chemical modalities and, therefore, are used best in combinationwith pharmacoprophylaxis [61].

The pharmacologic agents currently used in the thromboprophylaxis in-clude aspirin, warfarin, low molecular weight heparin, and fondaparinux.Aspirin is shown to reduce PE by 43% and symptomatic DVT by 29% indoses of 160 mg and 375 mg daily [62]. Warfarin is the pharmacoprophylacticagent used most commonly in patients after THA and TKA. Its effectivenessis demonstrated in many studies [61,62]. One such study shows that warfarinin combination with external pneumatic compression devices reduces theprevalence of DVT to 5% and bleeding complications to 0.9% [61]. Enoxa-parin, a low molecular weight heparin, is used commonly for prophylaxis

527ARTHROPLASTY IN THE GERIATRIC POPULATION

against thromoboembolism after joint replacement surgery. After THA andTKA, 30-mg doses of enoxaparin are given twice daily, typically 10 to 12hours postoperatively. Enoxaparin is a highly effective thromboprophylaxisagent, but its widespread use is limited by the documented increase incidenceof bleeding complications [63]. Its use is limited by coexistent renal insuffi-ciency, which is common in elderly surgical patients. Fondaparinux, a syn-thetic and specific inhibitor of activated factor X, has a long half andonce-a-day administration that makes it attractive; however, its effectivenessand its safety in older patients has not been investigated adequately.

Rehabilitation after hip and knee arthroplasty

There is an old adage in total joint arthroplasty surgery that states thatsuccessful outcomes of THA and TKA are equally dependent on thesurgeon and patient. The surgeon is responsible for performing the bestoperation possible for the patient, whereas the patient’s responsibilitycommences almost immediately after surgery in the form of rehabilitation,beginning in the hospital and continuing at home or skilled rehabilitationfacility. Currently, there is no evidence to support the effectiveness of inpa-tient physiotherapy on the eventual long-term outcomes of THA and TKA.Therefore, the generally accepted rehabilitation protocol in the UnitedStates usually is 1 or 2 days of physical and occupational therapy in the hos-pital setting with subsequent referral to a rehabilitation facility to continuefunctional restoration. Patients initially use walkers and then advance tocanes as muscle strength returns, which often is seen between 4 and 6 weekspostoperatively. Patient education plays an important role in the rehabilita-tion process, particularly in THA, where participation in risky activities canlead to hip dislocation. For example, patients are told to refrain from usinglow chairs or low beds or sitting in low baths and should sleep on theirbacks. Patients can expect to return to their usual activities, such as work,driving, and permissible recreational sports, 6 weeks post surgery. This gen-erally is true for patients over age 65 whose usual activities mean simplyhouse or community ambulation. Full functional restoration also dependson patients’ other underling comorbidities. Given the goals of the surgery,however, it is not unreasonable to expect the desire outcomes (describedin the previous statement), especially in motivated patients.

Future directions of hip and knee arthroplasty

Minimally invasive surgery and its role and effects on outcomes

Despite the success of TKA procedures, surgical techniques continuallystrive to improve patient outcomes. This process often includes improve-ments in instrumentation and technique. Throughout surgical subspe-cialties, minimally invasive surgery (MIS) techniques have been the recent

528 ST. CLAIR et al

trend. This trend is powered by goals of decreased patient pain, decreasedhospital stay and costs, and quicker return to patient goals and functionallevels. Standard approach to TKA traditionally has involved an 8- to14-inch midline skin incision down to the extensor mechanism with a para-medial arthrotomy, violating the medial aspect of the quadriceps tendon.Subsequent eversion and dislocation of the patella gains access to the artic-ular surface and entire tibiofemoral articulation. This approach allows un-matched visualization for appropriate component placement and ligamentbalancing, leading to proved clinical outcomes.

MIS TKA, as the name implies, involves using a limited incision (4–7 in)(Fig. 4). Subsequent subcutaneous dissection and arthrotomy then are com-pleted in a more limited fashion. Arthrotomy is undertaken through a mid-vastus, subvastus, parapatellar capsular, or lateral approach, depending onsurgeon preference. The key to the arthrotomy is to preserve as much conti-nuity of the quadriceps mechanism as possible. Along with incision lengthand dealing differently with the extensor mechanism, other differences in-clude patellar mobilization. MIS approaches limit patellar eversion, thus lim-iting tension on the quadriceps mechanism and preventing any subsequentextension of the arthrotomy. Additionally, tibiofemoral dislocation time isdecreased and limited only to tibial implantation, as necessary. Managementof the soft tissue, more so than incision length, is hypothesized as the majorcontributing factor for improved early results. Early retrospective resultsfrom other centers indicate positive results with these techniques [64,65].

The goals of MIS for total joint arthroplasty include decreased pain andquicker return to function without sacrificing component alignment and pa-tient safety. Patient concerns with MIS include long-term outcome and post-operative pain and length of recovery [66]. This issue is underscored bymany surgeons who advise patients that full functional recovery may takeup to 1 year. Evaluating these results will help the orthopedic communityto advance the ultimate goal of improved techniques and patient outcomes.

Fig. 4. Photograph of patient 4 weeks after bilateral minimally invasive TKA. Linear scar

length of approximately 4.5 in.

529ARTHROPLASTY IN THE GERIATRIC POPULATION

Computer-assisted navigation for hip and knee arthroplasty

The success of TKA is dependent on the proper alignment of the im-planted components. Computer-assisted navigation for TKA recently hasbecome an area of intense investigation and recently has been reported toincrease the accuracy of implantation [67,68] along with its reliability andreproducibility [69]. This increased precision may lead to improved out-comes and faster return to normal functions (Figs. 5 and 6).

Summary

OA is the leading cause of hip and knee pathology in the geriatric pop-ulation. Hip and knee arthroplasty are the definitive interventions to allevi-ate pain and restore physical functioning. Complications related to these

Fig. 5. (A1, 2) Preoperative lateral x-ray view of left knee showing severe deformity and degen-

erative arthritis. Postoperative lateral x-ray view of left knee showing TKA components in place

with mechanically neutral alignment using computer-assisted navigation surgery. (B1, 2) Preop-

erative and postoperative lateral views of right knee showing similar deformity and posterior

correction using TKA computer-assisted surgery.

530 ST. CLAIR et al

procedures occur: the most common of these are infection, thromboembo-lism, dislocations, and periprosthetic fractures. New improvements relatedto minimally invasive and computer-assisted navigation surgery techniquesare promising and already show excellent outcomes in patients exposed tojoint arthroplasty.

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