Special Focus Section
113
Evaluation of the Painful Total Knee Arthroplasty Richard Bassett, DO1
Steve Myerthall, MD1
1 Division of Adult Reconstruction, The CORE Institute, Center for
Orthopaedic Research and Education, Phoenix, Arizona J Knee Surg 2015;28:113–118.
Abstract
Keywords
► knee pain ► total knee arthroplasty ► failure
Address for correspondence Robert Cercek, MD, Division of Adult Reconstruction, The CORE Institute, Center for Orthopaedic Research and Education, 18444 N. 25th Avenue, Suite 210, Phoenix, AZ 85023 (e-mail: [email protected]).
There are a substantial number of patients who continue to complain of pain following total knee arthroplasty (TKA). There are many potential causes of continued pain, and these are broadly categorized into intrinsic and extrinsic sources. When evaluating a patient with a painful TKA, the physician begins with a thorough history and physical examination, along with the appropriate radiographs. Further workup includes laboratory analysis, specifically evaluating the inflammatory markers erythrocyte sedimentation rate and C-reactive protein, along with a synovial fluid aspirate evaluating the white blood cell count with differential and culture. Advanced imaging modalities are sometimes helpful when the diagnosis remains unclear, including stress radiographs, live fluoroscopic imaging, ultrasound, nuclear imaging, and magnetic resonance imaging. Further surgery is not advisable without a clear diagnosis, as this is associated with very poor results. Instead, serial follow-up or a referral to a specialist for a second opinion may be most appropriate.
Total knee arthroplasty (TKA) is one of the most common operative procedures that orthopedic surgeons perform each year. From the year 1991 to 2010, TKA in Medicare beneficiaries has increased over 150% from 93,230 to 243,802 procedures performed each year in the United States.1 In 2003, over 400,000 primary TKAs were performed for all beneficiaries in the United States, and this number is predicted to increase to over 3,000,000 by the year 2030. 2 Revision TKA has also increased from 9,650 to 19,871 procedures performed yearly. There remains a surprisingly high rate of dissatisfaction among patients receiving a TKA.3–6 Approximately 15 to 20% of patients who have received a TKA are dissatisfied following surgery because of continued pain or poor functional outcomes.7–11 Patient satisfaction is a multifactorial issue, as surgeonrelated technical issues, as well as issues outside of a surgeon’s control, can influence the patient-perceived surgical outcome. Patient-related issues may be related to the inability of knee replacement to reproduce native knee mechanics, producing a prosthetic knee which does not “feel” like the native knee, as well as dissatisfaction with the postoperative range of motion. 12–15 Unrealistic patient expectations may also lead to suboptimal results.
The potential causes of knee pain and dysfunction following a TKA are numerous. They can broadly be categorized into intrinsic (intra-articular) and extrinsic (extra-articular) causes. Intrinsic causes directly related to the joint arthroplasty procedure include infection, ligamentous instability (coronal instability, flexion instability, or global instability), component loosening or failure, polyethylene wear, osteolysis, arthrofibrosis, component malalignment, dysfunction of the extensor mechanism (instability, fracture, maltracking, patellar facet impingement, patella baja, inappropriate construct thickness, and tendon rupture), stress fracture, particulate-induced synovitis, loose body impingement, soft-tissue impingement, inappropriate component size (overhang), stem pain, intra-articular fibrous bands, popliteal tendon dysfunction, collateral ligament irritation, recurrent hemarthrosis, fat pad impingement, or heterotopic ossification. Extrinsic causes of pain not related directly to the joint include referred pain from the ipsilateral hip or the lumber spine (stenosis and radiculopathy), vascular pain, neurologic pain, tendonitis (iliotibial, patellar, and quadriceps), pes anserine bursitis, intrapelvic tumor, cutaneous neuroma, excessive preoperative narcotic consumption, reflex sympathetic dystrophy/complex regional pain syndrome, and
received September 21, 2014 accepted after revision October 23, 2014 published online November 24, 2014
Copyright © 2015 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) 584-4662.
DOI http://dx.doi.org/ 10.1055/s-0034-1396081. ISSN 1538-8506.
Downloaded by: The University of Hong Kong. Copyrighted material.
Robert Cercek, MD1
Evaluation of the Painful Total Knee Arthroplasty
Cercek et al.
psychological issues such as depression or anxiety. A thorough knowledge of these causes will enable the astute clinician to properly diagnose and manage the reason or reasons for a painful TKA.
History and Physical Examination A thorough history and physical examination are critical first steps in the evaluation of a painful TKA. They alone will often identify the etiology of pain. The primary symptom should be clearly identified: Is it pain? Instability? Swelling? Stiffness? The history should begin with information about the initial surgery including date, surgeon, implants used, review of operative reports if available, and review of preoperative radiographs if available. The nature and extent of the pain is important. How long has the pain been present? Where is the exact location of the pain and does it occur at rest or with activity? How long does the pain last and does anything make the pain better or worse? What is the pain intensity? Answers to these questions may guide the clinician to further investigate certain causes of pain. Pain that was present before the surgery and has persisted without change suggests an extrinsic etiology. Pain that began within the first year after the surgery suggests infection, instability, malposition, or softtissue impingement. Pain that began more than 1 year postoperatively suggests wear, osteolysis, component loosening, or infection. If a patient reports fevers or chills and pain that is not relieved with rest, a diagnosis of infection should be suspected. Likewise, details regarding the postoperative course of the index procedure should be obtained, including any prolonged postoperative wound drainage or delayed healing, any return to the operating room, and any treatment with antibiotics following surgery. Triphasic pain may be indicative of implant loosening. Comorbid conditions, such as diabetes, renal failure, peripheral vascular disease, and lumbar stenosis should be considered. If there appears to be no intrinsic cause of knee pain, the clinician must consider evaluating for extrinsic causes such as referred pain from the spine or hip. A thorough physical examination should be performed on every patient. Examination should include vital signs, general appearance, and a detailed inspection of the skin looking for lesions, redness, healed fistulas, and warmth. Examination of the spine, hip, and gait should be undertaken to rule out extrinsic causes of pain. A focused musculoskeletal examination of the knee should evaluate an active and passive range of motion, varus and valgus stability in flexion and extension, stability in the sagittal plane at 60 and 90 degrees of flexion to assess for midflexion and flexion stability, manual strength testing, palpation for swelling or focal tenderness, and evaluation of patellofemoral stability. The knee should be assessed for an effusion and evaluated for point tenderness along the iliotibial band and pes anserine bursa, which may be indicative of flexion instability.16 Patellar tracking should be assessed closely, as the patellofemoral compartment is a common source of continued pain following TKA. Patellar clunk refers to impingement of scar tissue along the undersurface of the quadriceps tendon, most frequently on the edge The Journal of Knee Surgery
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of the posterior stabilized femoral box, as the knee extends from a flexed position. While this condition was more common with older femoral box designs, this can occur with modern implant designs as well.17 Several factors are associated with painful patellar crepitance, including a greater number of previous knee surgeries, decreased patellar component size, decreased patellar composite thickness, shorter patellar tendon length, increased posterior femoral condylar offset, use of smaller femoral components, thicker tibial polyethylene inserts, and increased flexion of the femoral component.18 These factors are thought to increase quadriceps tendon contact forces against the superior aspect of the intercondylar box, thereby increasing the risk of fibrosynovial proliferation. A neurovascular examination should be performed and the quality and symmetry of the peripheral pulses should be assessed. The strength of the quadriceps and vastus medialis obliquus should be evaluated. The adjacent joints, specifically the ipsilateral hip and foot/ankle, should be inspected carefully as well.
Imaging Weight-bearing anteroposterior, lateral, PA flexed, and merchant view radiographs should be obtained for every patient. The anterior images should be closely evaluated for component position and size, component overhang, bony impingement, osteolysis, radiolucent lines, component subsidence, and fracture. The lateral images should be specifically evaluated for femoral component size, posterior femoral offset (►Fig. 1), patellar height and thickness, and tibial component slope. The merchant’s view should be evaluated for patellar component thickness, patellar tilt, patellar malalignment, femoral component overhang, and patellar facet impingement. Serial radiographs obtained over time prove particularly useful, including preoperative films when available. These may provide evidence for subtle signs of loosening, such as progression of radiolucent lines, changes in the cement mantle, progression of osteolysis, or change in component position. The radiographic images of the affected knee will often provide a diagnosis regarding the etiology of pain. Radiographs of the hips and spine may be warranted as directed by the physical examination. If additional information is desired regarding stability of the medial or lateral collateral ligaments, stress radiographs with varus and valgus stressing can be obtained. Fluoroscopic examination may also prove useful in the evaluation of the interface in cementless arthroplasty designs. If a cruciate retaining knee was used, the posterior cruciate ligament can also be evaluated for excessive knee translation during deep knee flexion. Poor fixation of the components can sometimes be found with these techniques. Osteolytic lesions are best evaluated with CT or MRI scans, preferably with metal artifact reduction, as the extent of these lesions are often underestimated or missed entirely on plain radiographs alone.19 These images can also be used to more accurately assess the rotation of the femoral and tibial components. The femoral component rotation is compared to the transepicondylar axis; the tibial component rotation is compared with the medial one-third of
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the tibial tubercle. Excessive internal rotation of either component can lead to patellar instability or lateral flexion laxity, contributing to knee pain and dysfunction.20 Radionucleotide scans may help in diagnosing component loosening, infection, and periprosthetic stress fractures. These studies should be interpreted with caution, as they are nonspecific, and can be falsely positive for up to 2 years postoperatively; a technetium bone scan demonstrates increased uptake in approximately in 90% of tibial components and 65% of femoral components at 1 year following TKA.21 When this study is obtained in the early postoperative time frame, it is best thought of as a baseline study, as subsequent study should show decreased uptake around the components. Technetium scans are sensitive, but these scans are unable to distinguish between septic and aseptic loosening. Indium 111–labeled scans have value for the exclusion of infection when they are negative, but a high false-positive rate has limited their usefulness.22,23 The specificity of this study can be improved by adding a sulfur colloid bone marrow scan, which corrects for physiologic marrow packing in the vicinity of the prosthetic components. Positron emission tomography (PET) imaging is being researched as a diagnostic modality to detect periprosthetic infection as well, and was recently demonstrated to be superior to combined Indium and sulfur colloid bone marrow scans in the detection of infection in painful hip and knee prostheses.24 MRI can be used if a mass or tumor is suspected. Given the relatively poor sensitivity and specificity and the high costs of these tests, however, advanced imaging should be reserved for secondline testing when the workup otherwise leads to equivocal findings.
Laboratory Testing Every patient presenting with a painful or failed TKA should be evaluated for a deep periprosthetic infection. Even with an obvious cause of pain, there is always the possibility of a concomitant infection. This should certainly be diagnosed
preoperatively, as the treatment pathway for an infectionrelated failure is vastly different from the treatment of an aseptic failure. There may be aspects of the medical history and physical examination which increase the suspicion for infection. Patient-related risk factors for infection include a history of diabetes, inflammatory arthropathy, a prior septic arthritis of the native knee, previous surgery on the knee, posttraumatic arthritis, skin disorders, malnourishment, revision knee surgery, an immunocompromised state, and renal insufficiency (especially if requiring dialysis).25 Basic laboratory testing includes a complete blood cell count with differential, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). The ESR and CRP are very sensitive for the diagnosis of infection, and if both the values are within normal limits, the risk of infection is very low.26 If either value is elevated or if clinical suspicion remains high, a synovial fluid aspiration should be obtained, and the fluid sent for white blood cell (WBC) count for differential and culture. The patient should not receive antibiotics for a minimum of 2 weeks before the aspiration to optimize the culture results. If the aspiration is negative but the suspicion for infection remains high, a repeat aspiration may be warranted. A synovial fluid WBC count between 1,100 and 3,000 cells/mm3 is strongly suggestive of a deep periprosthetic infection.26,27 These values are much lower than the 50,000 to 100,000 cells/mm3 range that suggests an infection in the native knee. The percentage of neutrophils in the aspirated fluid is also an accurate predictor of infection. If the percentage of neutrophils is between 60 and 80%, infection is likely. When the WBC count is below 1,100 cells/mm3 and the neutrophil percentage is less than 64%, the negative predictive value is 98.2%; when both values are greater than these numbers, the positive predictive value for infection is 98.6%.27 The AAOS recently published a clinical practice guideline summary for the diagnosis of periprosthetic joint infections of the hip and knee, which provides an excellent algorithm for the workup of these patients.28 It is important to bear in mind that the serologic markers (ESR/CRP), as well as the synovial fluid WBC count with differential remain elevated in the The Journal of Knee Surgery
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Fig. 1 (A) Poor posterior offset in a patient with symptomatic flexion instability. (B) Improved posterior offset after revision arthroplasty.
Evaluation of the Painful Total Knee Arthroplasty
Cercek et al.
acute postoperative period for at least 6 weeks, rendering the above cutoff values inaccurate. This is believed to be because of postoperative inflammation and a resolving hemarthrosis. The optimal synovial fluid WBC count cutoff value in the early postoperative time frame was determined to be 27,800 cells/ mm3, with a negative predictive value of 98%.29
Discussion The etiology of the painful TKA and the failed TKA has changed over the past 10 years. With the advent of new and improved polyethylene components, polyethylene wear and associated osteolysis are no longer the major contributors to the failed TKA.30,31 Researchers at The Rothman Institute reviewed all TKA revisions performed between 1997 to 2000, and found that the most common reason for revision surgery was polyethylene wear, followed by aseptic loosening, instability, infection, arthrofibrosis, malalignment, deficient extensor mechanism, periprosthetic fracture, and patellar resurfacing.32 They repeated this study in 2013, evaluating all TKA revisions performed from 2003 to 2012. They found the modes of failure in decreasing frequency to be component loosening (40%), infection (27%), instability (8%), periprosthetic fracture (4%), and arthrofibrosis (4%).30 Infection was the most common cause of failure less than 2 years postoperatively, and aseptic loosening was the most common cause of late failure. As infection and loosening are now the most common causes of TKA failure, they should be first on a clinician’s mind when evaluating a painful TKA. Anterior knee pain because of an un-resurfaced patella has been studied with variable results. Parvizi et al secondarily resurfaced 41 patellas and found that eight patients were not satisfied with the results of the secondary surgery.33 The author states that anterior knee pain after TKA has multiple etiologies, and the non-resurfaced patella is not the sole cause of this problem. If the pain seems to be related to the anterior compartment, the clinician should also evaluate the patella for signs of excessive bone left at the lateral facet. Excessive bone left uncovered by the patellar component can cause pain as it impinges on the femoral component in deep flexion. The Mayo Clinic recently reported a significant improvement in knee society function scores for patients undergoing revision surgery for lateral patellar facet impingement34 (►Fig. 2). Patellar clunk and patellar synovial hyperplasia are rare causes of knee pain after TKA, and this condition has been successfully treated with arthroscopic debridement.35 Tibial component overhang can be a source of pain following TKA. Lateral overhang is better tolerated than medial overhang due to irritation of the medial collateral ligament. Residual osteophytes or bone cement can also cause impingementrelated pain and may be visible on imaging studies. If these major causes of intrinsic knee pain have been ruled out, and extrinsic causes have also been ruled out, then the clinician must consider less common sources of knee pain. Workup of the spine with magnetic resonance imaging and/or electromyography may reveal a lumbar radiculopathy which is causing knee pain. Occult hip pathology may also be the cause of pain, such as avascular necrosis. A diagnostic injecThe Journal of Knee Surgery
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Fig. 2 (A) Lateral facet impingement in a patient with anterior knee pain. (B) Improved patellar coverage after revision of the patellar component.
tion into a native ipsilateral hip can be valuable in determining whether intra-articular hip pathology is resulting in knee pain.
Summary Preoperative factors can help predict which patients will have a high likelihood of residual pain after undergoing TKA. Patients with higher preoperative pain scores demonstrated with a simple active knee flexion/extension test have a 10times higher likelihood of pain 6 months after a TKA.36 Others have demonstrated that pain unexplained by an otherwise clinically sound TKA can be related to preoperative anxiety or depression.37,38 If a complete workup including a thorough history, physical examination, radiographic evaluation, and laboratory studies fail to determine a cause for pain after TKA, revision surgery is not generally recommended, as this is unlikely to improve the functional outcome and result in a decrease in pain.
References 1 Cram P, Lu X, Kates SL, Singh JA, Li Y, Wolf BR. Total knee
arthroplasty volume, utilization, and outcomes among Medicare beneficiaries, 1991-2010. JAMA 2012;308(12):1227–1236 2 Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am 2007;89(4):780–785
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3 Bourne RB, Chesworth BM, Davis AM, Mahomed NN, Charron KD.
21 Hofmann AA, Wyatt RW, Daniels AU, Armstrong L, Alazraki N,
Patient satisfaction after total knee arthroplasty: who is satisfied and who is not? Clin Orthop Relat Res 2010;468(1):57–63 Culliton SE, Bryant DM, Overend TJ, MacDonald SJ, Chesworth BM. The relationship between expectations and satisfaction in patients undergoing primary total knee arthroplasty. J Arthroplasty 2012; 27(3):490–492 Nilsdotter AK, Toksvig-Larsen S, Roos EM. Knee arthroplasty: are patients’ expectations fulfilled? A prospective study of pain and function in 102 patients with 5-year follow-up. Acta Orthop 2009; 80(1):55–61 Noble PC, Conditt MA, Cook KF, Mathis KB. The John Insall Award: Patient expectations affect satisfaction with total knee arthroplasty. Clin Orthop Relat Res 2006;452(452):35–43 Anderson JG, Wixson RL, Tsai D, Stulberg SD, Chang RW. Functional outcome and patient satisfaction in total knee patients over the age of 75. J Arthroplasty 1996;11(7):831–840 Dunbar MJ, Robertsson O, Ryd L, Lidgren L. Appropriate questionnaires for knee arthroplasty. Results of a survey of 3600 patients from The Swedish Knee Arthroplasty Registry. J Bone Joint Surg Br 2001;83(3):339–344 Hawker G, Wright J, Coyte P, et al. Health-related quality of life after knee replacement. J Bone Joint Surg Am 1998;80(2):163–173 Heck DA, Robinson RL, Partridge CM, Lubitz RM, Freund DA. Patient outcomes after knee replacement. Clin Orthop Relat Res 1998;(356):93–110 Jacobs CA, Christensen CP. Factors influencing patient satisfaction two to five years after primary total knee arthroplasty. J Arthroplasty 2014;29(6):1189–1191 Baker PN, van der Meulen JH, Lewsey J, Gregg PJ; National Joint Registry for England and Wales; Data from the National Joint Registry for England and Wales. The role of pain and function in determining patient satisfaction after total knee replacement. J Bone Joint Surg Br 2007;89(7):893–900 Chesworth BM, Mahomed NN, Bourne RB, Davis AM; OJRR Study Group. Willingness to go through surgery again validated the WOMAC clinically important difference from THR/TKR surgery. J Clin Epidemiol 2008;61(9):907–918 Jorn LP, Johnsson R, Toksvig-Larsen S. Patient satisfaction, function and return to work after knee arthroplasty. Acta Orthop Scand 1999;70(4):343–347 Robertsson O, Dunbar M, Pehrsson T, Knutson K, Lidgren L. Patient satisfaction after knee arthroplasty: a report on 27,372 knees operated on between 1981 and 1995 in Sweden. Acta Orthop Scand 2000;71(3):262–267 Clarke HD, Scuderi GR. Flexion instability in primary total knee replacement. J Knee Surg 2003;16(2):123–128 Peralta-Molero JV, Gladnick BP, Lee YY, Ferrer AV, Lyman S, González Della Valle A. Patellofemoral crepitation and clunk following modern, fixed-bearing total knee arthroplasty. J Arthroplasty 2014;29(3):535–540 Dennis DA, Kim RH, Johnson DR, Springer BD, Fehring TK, Sharma A. The John Insall Award: control-matched evaluation of painful patellar Crepitus after total knee arthroplasty. Clin Orthop Relat Res 2011;469(1):10–17 Reish TG, Clarke HD, Scuderi GR, Math KR, Scott WN. Use of multidetector computed tomography for the detection of periprosthetic osteolysis in total knee arthroplasty. J Knee Surg 2006;19(4): 259–264 Berger RA, Crossett LS, Jacobs JJ, Rubash HE. Malrotation causing patellofemoral complications after total knee arthroplasty. Clin Orthop Relat Res 1998;(356):144–153
Taylor A Jr. Bone scans after total knee arthroplasty in asymptomatic patients. Cemented versus cementless. Clin Orthop Relat Res 1990;(251):183–188 Rand JA, Brown ML. The value of indium 111 leukocyte scanning in the evaluation of painful or infected total knee arthroplasties. Clin Orthop Relat Res 1990;(259):179–182 Scher DM, Pak K, Lonner JH, Finkel JE, Zuckerman JD, Di Cesare PE. The predictive value of indium-111 leukocyte scans in the diagnosis of infected total hip, knee, or resection arthroplasties. J Arthroplasty 2000;15(3):295–300 Basu S, Kwee TC, Saboury B, et al. FDG PET for diagnosing infection in hip and knee prostheses: prospective study in 221 prostheses and subgroup comparison with combined (111)In-labeled leukocyte/(99m)Tc-sulfur colloid bone marrow imaging in 88 prostheses. Clin Nucl Med 2014;39(7):609–615 Jämsen E, Huhtala H, Puolakka T, Moilanen T. Risk factors for infection after knee arthroplasty. A register-based analysis of 43,149 cases. J Bone Joint Surg Am 2009;91(1):38–47 Della Valle CJ, Sporer SM, Jacobs JJ, Berger RA, Rosenberg AG, Paprosky WG. Preoperative testing for sepsis before revision total knee arthroplasty. J Arthroplasty 2007;22(6, Suppl 2): 90–93 Ghanem E, Parvizi J, Burnett RS, et al. Cell count and differential of aspirated fluid in the diagnosis of infection at the site of total knee arthroplasty. J Bone Joint Surg Am 2008;90(8):1637–1643 Della Valle C, Parvizi J, Bauer TW, et al; American Academy of Orthopaedic Surgeons. Diagnosis of periprosthetic joint infections of the hip and knee. J Am Acad Orthop Surg 2010;18(12): 760–770 Bedair H, Ting N, Jacovides C, et al. The Mark Coventry Award: diagnosis of early postoperative TKA infection using synovial fluid analysis. Clin Orthop Relat Res 2011;469(1):34–40 Sharkey PF, Lichstein PM, Shen C, Tokarski AT, Parvizi J. Why are total knee arthroplasties failing today—has anything changed after 10 years? J Arthroplasty 2014;29(9):1774–1778 Schroer WC, Berend KR, Lombardi AV, et al. Why are total knees failing today? Etiology of total knee revision in 2010 and 2011. J Arthroplasty 2013;28(8, Suppl):116–119 Sharkey PF, Hozack WJ, Rothman RH, Shastri S, Jacoby SM. Insall Award paper. Why are total knee arthroplasties failing today? Clin Orthop Relat Res 2002;(404):7–13 Parvizi J, Mortazavi SM, Devulapalli C, Hozack WJ, Sharkey PF, Rothman RH. Secondary resurfacing of the patella after primary total knee arthroplasty does the anterior knee pain resolve? J Arthroplasty 2012;27(1):21–26 Nikolaus OB, Larson DR, Hanssen AD, Trousdale RT, Sierra RJ. Lateral patellar facet impingement after primary total knee arthroplasty: it does exist. J Arthroplasty 2014;29(5):970–976 Costanzo JA, Aynardi MC, Peters JD, Kopolovich DM, Purtill JJ. Patellar clunk syndrome after total knee arthroplasty; risk factors and functional outcomes of arthroscopic treatment. J Arthroplasty 2014;29(9, Suppl):201–204 Noiseux NO, Callaghan JJ, Clark CR, Zimmerman MB, Sluka KA, Rakel BA. Preoperative predictors of pain following total knee arthroplasty. J Arthroplasty 2014;29(7):1383–1387 Feeney SL. The relationship between pain and negative affect in older adults: anxiety as a predictor of pain. J Anxiety Disord 2004; 18(6):733–744 Brander V, Gondek S, Martin E, Stulberg SD. Pain and depression influence outcome 5 years after knee replacement surgery. Clin Orthop Relat Res 2007;464(464):21–26
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Evaluation of the Painful Total Knee Arthroplasty
113
Evaluation of the Painful Total Knee Arthroplasty Richard Bassett, DO1
Steve Myerthall, MD1
1 Division of Adult Reconstruction, The CORE Institute, Center for
Orthopaedic Research and Education, Phoenix, Arizona J Knee Surg 2015;28:113–118.
Abstract
Keywords
► knee pain ► total knee arthroplasty ► failure
Address for correspondence Robert Cercek, MD, Division of Adult Reconstruction, The CORE Institute, Center for Orthopaedic Research and Education, 18444 N. 25th Avenue, Suite 210, Phoenix, AZ 85023 (e-mail: [email protected]).
There are a substantial number of patients who continue to complain of pain following total knee arthroplasty (TKA). There are many potential causes of continued pain, and these are broadly categorized into intrinsic and extrinsic sources. When evaluating a patient with a painful TKA, the physician begins with a thorough history and physical examination, along with the appropriate radiographs. Further workup includes laboratory analysis, specifically evaluating the inflammatory markers erythrocyte sedimentation rate and C-reactive protein, along with a synovial fluid aspirate evaluating the white blood cell count with differential and culture. Advanced imaging modalities are sometimes helpful when the diagnosis remains unclear, including stress radiographs, live fluoroscopic imaging, ultrasound, nuclear imaging, and magnetic resonance imaging. Further surgery is not advisable without a clear diagnosis, as this is associated with very poor results. Instead, serial follow-up or a referral to a specialist for a second opinion may be most appropriate.
Total knee arthroplasty (TKA) is one of the most common operative procedures that orthopedic surgeons perform each year. From the year 1991 to 2010, TKA in Medicare beneficiaries has increased over 150% from 93,230 to 243,802 procedures performed each year in the United States.1 In 2003, over 400,000 primary TKAs were performed for all beneficiaries in the United States, and this number is predicted to increase to over 3,000,000 by the year 2030. 2 Revision TKA has also increased from 9,650 to 19,871 procedures performed yearly. There remains a surprisingly high rate of dissatisfaction among patients receiving a TKA.3–6 Approximately 15 to 20% of patients who have received a TKA are dissatisfied following surgery because of continued pain or poor functional outcomes.7–11 Patient satisfaction is a multifactorial issue, as surgeonrelated technical issues, as well as issues outside of a surgeon’s control, can influence the patient-perceived surgical outcome. Patient-related issues may be related to the inability of knee replacement to reproduce native knee mechanics, producing a prosthetic knee which does not “feel” like the native knee, as well as dissatisfaction with the postoperative range of motion. 12–15 Unrealistic patient expectations may also lead to suboptimal results.
The potential causes of knee pain and dysfunction following a TKA are numerous. They can broadly be categorized into intrinsic (intra-articular) and extrinsic (extra-articular) causes. Intrinsic causes directly related to the joint arthroplasty procedure include infection, ligamentous instability (coronal instability, flexion instability, or global instability), component loosening or failure, polyethylene wear, osteolysis, arthrofibrosis, component malalignment, dysfunction of the extensor mechanism (instability, fracture, maltracking, patellar facet impingement, patella baja, inappropriate construct thickness, and tendon rupture), stress fracture, particulate-induced synovitis, loose body impingement, soft-tissue impingement, inappropriate component size (overhang), stem pain, intra-articular fibrous bands, popliteal tendon dysfunction, collateral ligament irritation, recurrent hemarthrosis, fat pad impingement, or heterotopic ossification. Extrinsic causes of pain not related directly to the joint include referred pain from the ipsilateral hip or the lumber spine (stenosis and radiculopathy), vascular pain, neurologic pain, tendonitis (iliotibial, patellar, and quadriceps), pes anserine bursitis, intrapelvic tumor, cutaneous neuroma, excessive preoperative narcotic consumption, reflex sympathetic dystrophy/complex regional pain syndrome, and
received September 21, 2014 accepted after revision October 23, 2014 published online November 24, 2014
Copyright © 2015 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) 584-4662.
DOI http://dx.doi.org/ 10.1055/s-0034-1396081. ISSN 1538-8506.
Downloaded by: The University of Hong Kong. Copyrighted material.
Robert Cercek, MD1
Evaluation of the Painful Total Knee Arthroplasty
Cercek et al.
psychological issues such as depression or anxiety. A thorough knowledge of these causes will enable the astute clinician to properly diagnose and manage the reason or reasons for a painful TKA.
History and Physical Examination A thorough history and physical examination are critical first steps in the evaluation of a painful TKA. They alone will often identify the etiology of pain. The primary symptom should be clearly identified: Is it pain? Instability? Swelling? Stiffness? The history should begin with information about the initial surgery including date, surgeon, implants used, review of operative reports if available, and review of preoperative radiographs if available. The nature and extent of the pain is important. How long has the pain been present? Where is the exact location of the pain and does it occur at rest or with activity? How long does the pain last and does anything make the pain better or worse? What is the pain intensity? Answers to these questions may guide the clinician to further investigate certain causes of pain. Pain that was present before the surgery and has persisted without change suggests an extrinsic etiology. Pain that began within the first year after the surgery suggests infection, instability, malposition, or softtissue impingement. Pain that began more than 1 year postoperatively suggests wear, osteolysis, component loosening, or infection. If a patient reports fevers or chills and pain that is not relieved with rest, a diagnosis of infection should be suspected. Likewise, details regarding the postoperative course of the index procedure should be obtained, including any prolonged postoperative wound drainage or delayed healing, any return to the operating room, and any treatment with antibiotics following surgery. Triphasic pain may be indicative of implant loosening. Comorbid conditions, such as diabetes, renal failure, peripheral vascular disease, and lumbar stenosis should be considered. If there appears to be no intrinsic cause of knee pain, the clinician must consider evaluating for extrinsic causes such as referred pain from the spine or hip. A thorough physical examination should be performed on every patient. Examination should include vital signs, general appearance, and a detailed inspection of the skin looking for lesions, redness, healed fistulas, and warmth. Examination of the spine, hip, and gait should be undertaken to rule out extrinsic causes of pain. A focused musculoskeletal examination of the knee should evaluate an active and passive range of motion, varus and valgus stability in flexion and extension, stability in the sagittal plane at 60 and 90 degrees of flexion to assess for midflexion and flexion stability, manual strength testing, palpation for swelling or focal tenderness, and evaluation of patellofemoral stability. The knee should be assessed for an effusion and evaluated for point tenderness along the iliotibial band and pes anserine bursa, which may be indicative of flexion instability.16 Patellar tracking should be assessed closely, as the patellofemoral compartment is a common source of continued pain following TKA. Patellar clunk refers to impingement of scar tissue along the undersurface of the quadriceps tendon, most frequently on the edge The Journal of Knee Surgery
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of the posterior stabilized femoral box, as the knee extends from a flexed position. While this condition was more common with older femoral box designs, this can occur with modern implant designs as well.17 Several factors are associated with painful patellar crepitance, including a greater number of previous knee surgeries, decreased patellar component size, decreased patellar composite thickness, shorter patellar tendon length, increased posterior femoral condylar offset, use of smaller femoral components, thicker tibial polyethylene inserts, and increased flexion of the femoral component.18 These factors are thought to increase quadriceps tendon contact forces against the superior aspect of the intercondylar box, thereby increasing the risk of fibrosynovial proliferation. A neurovascular examination should be performed and the quality and symmetry of the peripheral pulses should be assessed. The strength of the quadriceps and vastus medialis obliquus should be evaluated. The adjacent joints, specifically the ipsilateral hip and foot/ankle, should be inspected carefully as well.
Imaging Weight-bearing anteroposterior, lateral, PA flexed, and merchant view radiographs should be obtained for every patient. The anterior images should be closely evaluated for component position and size, component overhang, bony impingement, osteolysis, radiolucent lines, component subsidence, and fracture. The lateral images should be specifically evaluated for femoral component size, posterior femoral offset (►Fig. 1), patellar height and thickness, and tibial component slope. The merchant’s view should be evaluated for patellar component thickness, patellar tilt, patellar malalignment, femoral component overhang, and patellar facet impingement. Serial radiographs obtained over time prove particularly useful, including preoperative films when available. These may provide evidence for subtle signs of loosening, such as progression of radiolucent lines, changes in the cement mantle, progression of osteolysis, or change in component position. The radiographic images of the affected knee will often provide a diagnosis regarding the etiology of pain. Radiographs of the hips and spine may be warranted as directed by the physical examination. If additional information is desired regarding stability of the medial or lateral collateral ligaments, stress radiographs with varus and valgus stressing can be obtained. Fluoroscopic examination may also prove useful in the evaluation of the interface in cementless arthroplasty designs. If a cruciate retaining knee was used, the posterior cruciate ligament can also be evaluated for excessive knee translation during deep knee flexion. Poor fixation of the components can sometimes be found with these techniques. Osteolytic lesions are best evaluated with CT or MRI scans, preferably with metal artifact reduction, as the extent of these lesions are often underestimated or missed entirely on plain radiographs alone.19 These images can also be used to more accurately assess the rotation of the femoral and tibial components. The femoral component rotation is compared to the transepicondylar axis; the tibial component rotation is compared with the medial one-third of
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the tibial tubercle. Excessive internal rotation of either component can lead to patellar instability or lateral flexion laxity, contributing to knee pain and dysfunction.20 Radionucleotide scans may help in diagnosing component loosening, infection, and periprosthetic stress fractures. These studies should be interpreted with caution, as they are nonspecific, and can be falsely positive for up to 2 years postoperatively; a technetium bone scan demonstrates increased uptake in approximately in 90% of tibial components and 65% of femoral components at 1 year following TKA.21 When this study is obtained in the early postoperative time frame, it is best thought of as a baseline study, as subsequent study should show decreased uptake around the components. Technetium scans are sensitive, but these scans are unable to distinguish between septic and aseptic loosening. Indium 111–labeled scans have value for the exclusion of infection when they are negative, but a high false-positive rate has limited their usefulness.22,23 The specificity of this study can be improved by adding a sulfur colloid bone marrow scan, which corrects for physiologic marrow packing in the vicinity of the prosthetic components. Positron emission tomography (PET) imaging is being researched as a diagnostic modality to detect periprosthetic infection as well, and was recently demonstrated to be superior to combined Indium and sulfur colloid bone marrow scans in the detection of infection in painful hip and knee prostheses.24 MRI can be used if a mass or tumor is suspected. Given the relatively poor sensitivity and specificity and the high costs of these tests, however, advanced imaging should be reserved for secondline testing when the workup otherwise leads to equivocal findings.
Laboratory Testing Every patient presenting with a painful or failed TKA should be evaluated for a deep periprosthetic infection. Even with an obvious cause of pain, there is always the possibility of a concomitant infection. This should certainly be diagnosed
preoperatively, as the treatment pathway for an infectionrelated failure is vastly different from the treatment of an aseptic failure. There may be aspects of the medical history and physical examination which increase the suspicion for infection. Patient-related risk factors for infection include a history of diabetes, inflammatory arthropathy, a prior septic arthritis of the native knee, previous surgery on the knee, posttraumatic arthritis, skin disorders, malnourishment, revision knee surgery, an immunocompromised state, and renal insufficiency (especially if requiring dialysis).25 Basic laboratory testing includes a complete blood cell count with differential, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). The ESR and CRP are very sensitive for the diagnosis of infection, and if both the values are within normal limits, the risk of infection is very low.26 If either value is elevated or if clinical suspicion remains high, a synovial fluid aspiration should be obtained, and the fluid sent for white blood cell (WBC) count for differential and culture. The patient should not receive antibiotics for a minimum of 2 weeks before the aspiration to optimize the culture results. If the aspiration is negative but the suspicion for infection remains high, a repeat aspiration may be warranted. A synovial fluid WBC count between 1,100 and 3,000 cells/mm3 is strongly suggestive of a deep periprosthetic infection.26,27 These values are much lower than the 50,000 to 100,000 cells/mm3 range that suggests an infection in the native knee. The percentage of neutrophils in the aspirated fluid is also an accurate predictor of infection. If the percentage of neutrophils is between 60 and 80%, infection is likely. When the WBC count is below 1,100 cells/mm3 and the neutrophil percentage is less than 64%, the negative predictive value is 98.2%; when both values are greater than these numbers, the positive predictive value for infection is 98.6%.27 The AAOS recently published a clinical practice guideline summary for the diagnosis of periprosthetic joint infections of the hip and knee, which provides an excellent algorithm for the workup of these patients.28 It is important to bear in mind that the serologic markers (ESR/CRP), as well as the synovial fluid WBC count with differential remain elevated in the The Journal of Knee Surgery
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Fig. 1 (A) Poor posterior offset in a patient with symptomatic flexion instability. (B) Improved posterior offset after revision arthroplasty.
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acute postoperative period for at least 6 weeks, rendering the above cutoff values inaccurate. This is believed to be because of postoperative inflammation and a resolving hemarthrosis. The optimal synovial fluid WBC count cutoff value in the early postoperative time frame was determined to be 27,800 cells/ mm3, with a negative predictive value of 98%.29
Discussion The etiology of the painful TKA and the failed TKA has changed over the past 10 years. With the advent of new and improved polyethylene components, polyethylene wear and associated osteolysis are no longer the major contributors to the failed TKA.30,31 Researchers at The Rothman Institute reviewed all TKA revisions performed between 1997 to 2000, and found that the most common reason for revision surgery was polyethylene wear, followed by aseptic loosening, instability, infection, arthrofibrosis, malalignment, deficient extensor mechanism, periprosthetic fracture, and patellar resurfacing.32 They repeated this study in 2013, evaluating all TKA revisions performed from 2003 to 2012. They found the modes of failure in decreasing frequency to be component loosening (40%), infection (27%), instability (8%), periprosthetic fracture (4%), and arthrofibrosis (4%).30 Infection was the most common cause of failure less than 2 years postoperatively, and aseptic loosening was the most common cause of late failure. As infection and loosening are now the most common causes of TKA failure, they should be first on a clinician’s mind when evaluating a painful TKA. Anterior knee pain because of an un-resurfaced patella has been studied with variable results. Parvizi et al secondarily resurfaced 41 patellas and found that eight patients were not satisfied with the results of the secondary surgery.33 The author states that anterior knee pain after TKA has multiple etiologies, and the non-resurfaced patella is not the sole cause of this problem. If the pain seems to be related to the anterior compartment, the clinician should also evaluate the patella for signs of excessive bone left at the lateral facet. Excessive bone left uncovered by the patellar component can cause pain as it impinges on the femoral component in deep flexion. The Mayo Clinic recently reported a significant improvement in knee society function scores for patients undergoing revision surgery for lateral patellar facet impingement34 (►Fig. 2). Patellar clunk and patellar synovial hyperplasia are rare causes of knee pain after TKA, and this condition has been successfully treated with arthroscopic debridement.35 Tibial component overhang can be a source of pain following TKA. Lateral overhang is better tolerated than medial overhang due to irritation of the medial collateral ligament. Residual osteophytes or bone cement can also cause impingementrelated pain and may be visible on imaging studies. If these major causes of intrinsic knee pain have been ruled out, and extrinsic causes have also been ruled out, then the clinician must consider less common sources of knee pain. Workup of the spine with magnetic resonance imaging and/or electromyography may reveal a lumbar radiculopathy which is causing knee pain. Occult hip pathology may also be the cause of pain, such as avascular necrosis. A diagnostic injecThe Journal of Knee Surgery
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Fig. 2 (A) Lateral facet impingement in a patient with anterior knee pain. (B) Improved patellar coverage after revision of the patellar component.
tion into a native ipsilateral hip can be valuable in determining whether intra-articular hip pathology is resulting in knee pain.
Summary Preoperative factors can help predict which patients will have a high likelihood of residual pain after undergoing TKA. Patients with higher preoperative pain scores demonstrated with a simple active knee flexion/extension test have a 10times higher likelihood of pain 6 months after a TKA.36 Others have demonstrated that pain unexplained by an otherwise clinically sound TKA can be related to preoperative anxiety or depression.37,38 If a complete workup including a thorough history, physical examination, radiographic evaluation, and laboratory studies fail to determine a cause for pain after TKA, revision surgery is not generally recommended, as this is unlikely to improve the functional outcome and result in a decrease in pain.
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21 Hofmann AA, Wyatt RW, Daniels AU, Armstrong L, Alazraki N,
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