Research Article. Abstract

Transcription

1 Research Article Total Knee Arthroplasty in Patients With Cerebral Palsy: A Matched Cohort Study to Patients With Osteoarthritis Matthew T. Houdek, MD Chad D. Watts, MD Cody C. Wyles, MD Robert T. Trousdale, MD Todd J. Milbrandt, MD Michael J. Taunton, MD Abstract Introduction: Currently, few data examine the use of total knee arthroplasty (TKA) in patients with cerebral palsy (CP). This study reviewed the outcomes of TKA in patients with CP compared with a matched cohort undergoing TKA for primary osteoarthritis. Methods: Over a 28-year period, 15 TKAs in patients with a diagnosis of CP were identified. The cohort was 53% men, with a mean age of 58 years. Patients with CP were matched 1:2 based on age, sex, body mass index, and year of surgery with a group of patients undergoing TKA for osteoarthritis. Results: No difference was reported in implant survival (P = 0.27) or revision surgery (P = 0.79) between groups. All patients were ambulatory postoperatively, and significant increases were noted in the Knee Society score (P, ) and functional assessment (P = 0.003). Discussion: TKA is a safe, durable procedure in patients with CP to improve pain and function. From the Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN. Correspondence to Dr. Houdek: houdek.matthew@mayo.edu J Am Acad Orthop Surg 2017;25: DOI: /JAAOS-D Copyright 2017 by the American Academy of Orthopaedic Surgeons. Knee pain and altered gait mechanics often develop in patients with cerebral palsy (CP) because of increased femoral anteversion, tibial torsion, alteration in the patellofemoral joint, and hamstring contractures. 1-4 These changes can result in osteopenia, accelerating subchondral sclerosis, and cartilage thinning. 2 Hamstring lengthening, extension and rotational osteotomies of the distal femur, and patellar tendon advancements have all been used to correct the flexion deformity and reduce pain. 5-9 However, after arthrosis occurs, treatment options for these patients are limited. Total knee arthroplasty (TKA) is the most definitive management for the treatment of severe knee arthrosis. The use of total hip arthroplasty in patients with CP has shown success at long-term follow-up in unmatched series for osteoarthritis (OA) of the hip; 10,11 however, few data similarly examine the use of TKA in patients with CP. This study compared our institution s results following primary TKA performed in patients with CP with a matched cohort with uncomplicated primary OA. Methods Following Institutional Review Board approval, we used our institutional total joint registry to identify and examine the medical records of all patients who underwent primary TKA over a 28-year period (1985 to 2013). Primary outcome measures May 2017, Vol 25, No 5 381

2 Total Knee Arthroplasty in Patients With Cerebral Palsy Table 1 Demographics of Patients With Cerebral Palsy Undergoing Total Knee Arthroplasty Demographic Cerebral Palsy TKA Osteoarthritis TKA P Value Mean age (yr) 58 (range, 45 71) 58 (range, 45 71) 1.0 Mean BMI (kg/m 2 ) 29.8 (range, ) 29.2 (range, ) 0.73 Male:female ratio 8:7 16: GMFCS level I 2 II 6 III 6 IV 1 BMI = body mass index, GMFCS = Gross Motor Function Classification System, TKA = total knee arthroplasty included revision TKA (subsequent removal or exchange of any components), revision surgery on the affected knee for any reason without exchange of components, and postoperative complications, including infection, flexion contracture, limited knee range of motion (ie, $15 flexion contracture or #90 of total knee flexion), periprosthetic fracture, deep vein thrombosis, and wound complications, including hematoma and dehiscence. Cerebral Palsy Patient Cohort Fifteen of 27,611 TKAs (0.05%) were performed in patients diagnosed with CP. The cohort included eight men and seven women (mean age, 58 years; range, 45 to 71 years) with a mean body mass index (BMI) of 29.8 kg/m 2 (range, 22.0 to 41.0 kg/m 2 ) (Table 1). The Gross Motor Function Classification System (GMFCS) rating is shown in Table Prior to surgery, all 15 patients could walk with the use of assistive devices, and GMFCS levels were assigned as follows: I (n = 2), II (n = 6), III (n = 6), and IV (n = 1). Two patients were primarily wheelchair-bound immediately before surgery because of pain and disability from knee arthrosis but could ambulate short distances with a walker (Table 3). To achieve a balanced knee, augmentations to the standard TKA included extended posterior capsular release (n = 3), iliotibial band release (n = 3), popliteus release (n = 1), and collateral ligament release (n = 1) (Table 4). In one patient, a quadriceps snip was required to increase exposure. No patients underwent supplementary hamstring release or botulinum toxin type A injection. Preoperatively, seven patients had a flexion contracture of $15 and six patients had patella alta, as defined by a Modified Insall-Salvati ratio Following TKA, five patients had residual patella alta. Six patients had preoperative valgus deformity, which was corrected during TKA. Similarly, six patients had a combined history of seven previous surgical procedures on the leg. Procedures included adductor tendon release (n = 3), hamstring release (n = 2), and arthroscopic partial meniscectomy (n = 2). The components used were posterior stabilized (n = 11; Figure 1), semiconstrained (n = 3), and hinged (n = 1; Figure 2). All patients with increased constraint had patella alta and flexion contracture preoperatively. Knee Society scores (KSS) and KSS functional (KSSf) assessments were calculated preoperatively and at the most recent clinical follow-up. 14 Among all patients who underwent TKA for primary OA over the same period (21,838 from 1985 to 2013), 30 were chosen to achieve 1:2 matching. Matching criteria included sex, age, date of surgery 6 3 years, and BMI 6 3 kg/m 2. All patients were followed longitudinally to the time of implant revision or death, with all patients having at least 2 years of clinical follow-up. The outcome of the procedures was blinded at the time of matching. The matched comparison group had 16 men and 14 women, with a mean age of 58 years (range, 45 to 71 years) and a BMI of 29.2 kg/m 2 Dr. Trousdale or an immediate family member has received royalties from DePuy Synthes and Medtronic; serves as a paid consultant to DePuy Synthes; and serves as a board member, owner, officer, or committee member of the American Association of Hip and Knee Surgeons, The Hip Society, and The Knee Society. Dr. Milbrandt or an immediate family member serves as a paid consultant to Orthopediatrics; has stock or stock options held in Viking Scientific; has received nonincome support (such as equipment or services), commercially derived honoraria, or other non-research related funding (such as paid travel) from Broadwater; and serves as a board member, owner, officer, or committee member of the American Academy of Orthopaedic Surgeons, the Pediatric Orthopaedic Society of North America, and the Scoliosis Research Society. Dr. Taunton or an immediate family member has received royalties from and serves as a paid consultant to DJ Orthopaedics; has received research or institutional support from Stryker; and serves as a board member, owner, officer, or committee member of the American Academy of Orthopaedic Surgeons and the Minnesota Orthopaedic Society. None of the following authors or any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this article: Dr. Houdek, Dr. Watts, and Dr. Wyles. 382 Journal of the American Academy of Orthopaedic Surgeons

3 Matthew T. Houdek, MD, et al (range, 20.1 to 43.0 kg/m 2 ) at the time of surgery. No difference was noted in the mean BMI between cohorts (P = 0.73). Mean follow-up was 8 years in each group (range, 2 to 20 years). Statistical Analysis Categorical variables between groups were analyzed using Fisher exact tests. Continuous variables were compared using unpaired Student t-tests. Kaplan-Meier methodology was employed to estimate overall survival, and comparisons between the CP and OA groups were made using the logrank test. A P value, 0.05 was considered significant. Results Revision surgery was performed in two patients with CP: one for deep infection at 4 months and one for polyethylene wear and tibial component loosening at 12 years. Table 2 Gross Motor Function Classification System GMFCS Level Functional Ability I II III IV V Can walk indoors and outdoors without limitation Able to climb stairs without limitation Able to run and jump Speed, balance, and coordination often impaired Can walk indoors and outdoors without gait aid on even surfaces Have difficulty walking on uneven surfaces, inclines, and declines Needs to use a hand rail to climb stairs Difficulty walking in crowds and confined spaces Can walk indoors and outdoors on an even surface with a gait aid (ie, walker or forearm crutches) Able to climb stairs but requires a hand rail Able to use a self-propelled wheelchair Often uses a wheelchair for uneven surfaces or when traveling long distances Can walk short distances on level ground indoors and outdoors with a gait aid (ie, walker or forearm crutches) Able to use an electric wheelchair Often function from a wheelchair base in the community and home No voluntary control of movement No ability to control head and trunk antigravity positioning No means of independent mobility GMFCS = Gross Motor Function Classification System Data obtained from Palisano R, Rosenbaum P, Walter S, Russell D, Wood E, Galuppi B: Development and reliability of a system to classify gross motor function in children with cerebral palsy. Dev Med Child Neurol 1997;39(4): Table 3 Preoperative Status of Patients With Cerebral Palsy Undergoing Total Knee Arthroplasty Patient Sex/ Age (yr) GMFCS Level Gait Aid Patella Alta Flexion Contracture Prior Surgery Valgus Deformity ROM KSS/ KSSf Male/67 II Wheelchair/walker Yes Yes Hamstring release, Yes 60 26/30 adductor release Male/61 III Cane No Yes No No 70 20/30 Male/47 III Walker No No Partial meniscectomy Yes /5 Female/59 II Walker No Yes No Yes 75 46/15 Female/60 III Cane Yes Yes Hamstring release Yes 10 4/0 Male/58 II Cane Yes Yes No No 80 53/40 Female/45 I Cane No No No No 90 53/15 Female/46 I Cane No No No No 90 53/30 Male/65 III Cane No No Partial meniscectomy Yes 80 59/20 Male/71 III Cane No Yes No No 65 54/20 Female/67 IV Wheelchair/walker Yes No Adductor release Yes 20 36/0 Female/53 II Walker Yes No No No 96 57/35 Male/56 II Walker No No Adductor release No 80 58/0 Male/61 III Cane No Yes No No 70 20/30 Female/56 II Walker Yes No No No 60 37/5 GMFCS = Gross Motor Function Classification System, KSS = Knee Society score, KSSf = Knee Society score functional, ROM = range of motion May 2017, Vol 25, No 5 383

4 Total Knee Arthroplasty in Patients With Cerebral Palsy Table 4 Postoperative Outcome in Patients With Cerebral Palsy Undergoing Total Knee Arthroplasty Patient Surgical Augment TKA Constraint Gait Aid Complication Flexion Contracture ROM KSS/ KSSf 1 Posterior capsule release, iliotibial band release Semiconstrained Single crutch No No 82 88/15 2 None PS None No No 130 o 100/70 3 None PS Walker Hematoma, delayed healing, deep infection 4 None PS Walker Patellar subluxation, No 80 o 82/30 polyethylene wear 5 Quadriceps snip, Semiconstrained Cane No No 70 o 89/30 posterior capsule release 6 Posterior capsule Rotating hinge None No No 120 o 99/50 release, collateral ligament release 7 None PS None No No 100 o 95/89 8 None PS None No No 100 o 95/89 9 None PS Cane No No 120 o 99/30 10 None PS Cane No Yes 105 o 89/30 11 Popliteus release, Semiconstrained Walker No No 90 o 93/0 iliotibial band release 12 Iliotibial band release PS Cane No No 110 o 92/45 13 None PS Cane No No 120 o 79/45 14 None PS None No No 130 o 100/70 15 None PS Cane No No 60 o 57/35 KSS = Knee Society score, KSSf = Knee Society score functional, PS = posterior stabilized, ROM = range of motion, TKA = total knee arthroplasty Estimated implant survival for primary TKA in patients with CP at 2, 5, and 10 years was 93% for all points. No difference overall was reported (P = 0.27) compared with patients with a diagnosis of OA whose implant survival at 2, 5, and 10 years was 100%, 94%, and 94%, respectively. In the OA cohort, revision TKA was performed in two patients: one for deep infection at 5 years and one for tibial component loosening with polyethylene wear at 11 years. In the CP cohort, no additional surgeries were reported beyond the two revisions. Including the two revisions in the OA cohort, a total of four patients underwent revision surgery. The additional procedures in the OA cohort were manipulations under anesthesia (n = 2). No increased risk of revision surgery was reported in patients with CP (hazard ratio, 1.26; P = 0.79) compared with patients with OA. Complications occurred in six patients with CP. Two patients had multiple complications; one had patellar subluxation and polyethylene wear, and the other had delayed wound healing, hematoma formation, and a subsequent deep postoperative infection (Table 4). One patient had a persistent knee flexion contracture of 15, which was similar to the preoperative contracture. Similarly, three patients were unable to achieve 90 of knee flexion; however, no cases of manipulation under anesthesia were reported (Table 5). Prior to surgery, all patients had severe or moderate pain that was significantly reduced postoperatively in all but one patient (P, ). Preoperatively, six patients in the CP group had a knee flexion contracture of $15 ; this was corrected in five patients to at least,10 following surgery (P = 0.01). Furthermore, nine CP patients had improved ability to ambulate independently as judged by progression to the use of less cumbersome gait aids or no need for gait aids (Figure 3). Compared with preoperative status, improvement was significant in the proportion of patients who were independent ambulators following TKA (zero versus 33%; P = 0.04). Preoperatively, the mean knee range of motion was 71 (range, 10 to 120 ), which improved 384 Journal of the American Academy of Orthopaedic Surgeons

5 Matthew T. Houdek, MD, et al Figure 1 Preoperative AP (A) and lateral (B) radiographs of a patient with cerebral palsy and knee pain. Appropriate flexion and extension gaps were obtained with a posterior stabilized arthroplasty. AP (C) and lateral (D) radiographs of knee obtained 5 years after surgery. The patient remains pain free and has acceptable knee function. Figure 2 Preoperative AP (A and B) and lateral (C) radiographs of a patient with cerebral palsy and knee pain. In addition to arthrosis, the patient also had patella alta and a flexion contracture. A primary hinge knee arthroplasty was performed to release the collateral ligaments and posterior capsule to achieve knee extension. Two-year postoperative AP (D) and lateral (E) radiographs show no loosening or wear. significantly to 101 (range, 60 to 130 ; P, ). No difference was reported in the mean postoperative range of motion between patients with CP and those with primary OA (101 versus 110 ; P =0.11). In patients with CP, the mean preoperative KSS was 42 (range, 4 to 59) and the mean preoperative KSSf was18(range,0to40);thesevalues improved postoperatively to 90 (range, 57 to 100; P, ) and May 2017, Vol 25, No 5 385

6 Total Knee Arthroplasty in Patients With Cerebral Palsy Table 5 Comparison of Postoperative Complications Complication Cerebral Palsy Group Osteoarthritis Group Odds Ratio (95% CI) P Value Deep infection ( ) 1.0 Patellar subluxation ( ) 1.0 Polyethylene wear ( ) 1.0 Limited knee range of motion ( ) 0.43 Manipulation under anesthesia Deep vein thrombosis Periprosthetic fracture CI = confidence interval Figure 3 Following total knee arthroplasty in patients with cerebral palsy, all patients were ambulatory. Although most patients required some form of gait aid preoperatively and postoperatively, five patients were able to ambulate independently. 45 (range, 0 to 89; P = 0.003), respectively. Patients with patella alta had a significantly worse mean postoperative KSSf compared with those without (29 versus 57; P = 0.04). No difference was reported in the postoperative KSS for patients with CP compared with those with primary OA (90 versus 92; P = 0.67); however, patients with CP had a significantly lower mean postoperative KSSf compared with patients with OA (45 versus 80; P, ). Discussion TKA has been shown to relieve pain and restore function in patients with knee OA. Although not as common as symptomatic hip arthritis in patients with CP, knee arthritis can be debilitating, limiting the patient s ability to ambulate and sit. Although TKA is considered extremely successful in relieving OA pain and improving patient function, outcome data in patients with CP are limited. This case series examined TKA outcomes in patients with CP compared with patients with OA from a single institution. Functional assessment following TKA in the setting of CP is difficult because many patients with CP cannot be standardized to the current TKA rating systems. 14,15 The spasticity and poor muscle control often observed in patients with CP result in altered gait mechanics, which forces patients to ambulate with gait aids or only for short distances. These factors are major components of standard knee scores, in particular the KSSf, 14 which may explain why the KSSf results were substantially worse for patients with CP compared with those with OA. Although the KSSf was substantially less in patients with CP, all patients could ambulate postoperatively, and 33% of patients ambulated without a gait aid. Patella alta is common in patients with CP and is associated with a crouched gait and anterior knee pain, thus limiting the distance patients 386 Journal of the American Academy of Orthopaedic Surgeons

7 Matthew T. Houdek, MD, et al can walk Nonsurgical techniques for correcting patella alta and improving patellar congruence include quadriceps stretching, patellar bracing, and botulinum toxin A injection; however, when these nonsurgical measures fail, multilevel surgical procedures (ie, combined hip and knee) are often required. 17 In our series, six patients who had preoperative patella alta had markedly worse KSSf results following the procedure, which likely is related to the distance the patient can walk and the ability to climb stairs because these factors are dominant in this scoring system. Because of the small number of patients in the series, we are unable to determine if a procedure to correct patella alta before TKA could improve outcome. Following TKA, only one patient underwent correction of patella alta. We believe the preoperative patella alta likely resulted from a preoperative flexion contracture, and the patella alta was rectified with correction of the contracture. In patients with patella alta, additional resection of the distal femur may be necessary to improve extension; however, we do not recommend performing this in all patients. In patients with CP and patella alta, we would not sacrifice achieving a balanced knee to correct patella alta; the goal of the procedure is to achieve a knee with balanced flexion and extension gaps. When performing TKA in the setting of CP with patella alta, the surgeon should be prepared to perform TKA with an increased level of constraint compared with patients without patella alta. In addition to functional impairment, the pain from knee arthrosis can have a substantial effect on the quality of life of patients with CP and has been associated with a decline in the GMFCS levels over time. 20 The presence of knee pain has been reported to be as high as 39% in patients with CP and is found to increase with age. 21 The results of this study indicate that TKA is an effective means of reducing knee pain in patients with CP and concomitant arthrosis. Historically, the use of TKA to treat OA in the setting of neuromuscular flexion contractures, such as Parkinsonism, was contraindicated, citing complications such as hamstring contracture, flexion deformity, inability to perform rehabilitation, and poor muscle coordination Larger series showed improved functional and pain scores without these complications The spasticity and poor muscle coordination seen in patients with Parkinsonism is functionally similar to the hamstring contractures and altered gait mechanics of patients with CP. Our study aligned with this observation because we noticed an improvement in patient pain and function with TKA; however, the functional improvement was substantially less than that in patients with primary OA. The results of this study should be analyzed, given several limitations. The data were collected retrospectively, which limits the analysis; however, the prospective nature of the total joint registry helps reduce recall bias. Less than 0.1% of all TKAs performed at our institution during the study period were performed on patients with CP, resulting in an obvious selection bias. Given the limited participation, we were unable to analyze other potential confounding comorbidities that could influence outcome. This limitation was compensated for by performing a matched cohort analysis with twice as many patients with OA. Similarly, it is possible that the study is underpowered to detect differences in patient outcomes. TKA provides substantial pain relief and functional improvement for patients with CP. Patients with CP should expect similar outcomes in implant survival, need for revision surgery, and postoperative complications compared with patients with primary OA. We believe that TKA is a durable treatment option for patients with CP and knee pain, with substantial improvement in patient function and pain; however, additional caution should be exercised in patients with patella alta. References Evidence-based Medicine: Levels of evidence are described in the table of contents. In this article, reference 12 is a level I study. References 4, 13, and 15 are level II studies. References 9, 16, 18, and 20 are level III studies. References 5-8, 10, 11, 17, 19, and are level IV studies. References 1-3 and 14 are level V expert opinion. References printed in bold type are those published within the past 5 years. 1. Horstmann HM, Hosalkar H, Keenan MA: Orthopaedic issues in the musculoskeletal care of adults with cerebral palsy. Dev Med Child Neurol 2009;51(suppl 4): Carter DR, Tse B: The pathogenesis of osteoarthritis in cerebral palsy. Dev Med Child Neurol 2009;51(suppl 4): Perry J, Antonelli D, Ford W: Analysis of knee-joint forces during flexed-knee stance. J Bone Joint Surg Am 1975;57(7): Choi Y, Lee SH, Chung CY, et al: Anterior knee pain in patients with cerebral palsy. Clin Orthop Surg 2014;6(4): de Morais Filho MC, Neves DL, Abreu FP, Juliano Y, Guimarães L: Treatment of fixed knee flexion deformity and crouch gait using distal femur extension osteotomy in cerebral palsy. J Child Orthop 2008;2(1): Grujic H, Aparisi T: Distal hamstring tendon release in knee flexion deformity. Int Orthop 1982;6(2): Chang WN, Tsirikos AI, Miller F, et al: Distal hamstring lengthening in ambulatory children with cerebral palsy: Primary versus revision procedures. Gait Posture 2004;19 (3): Baumann JU, Ruetsch H, Schürmann K: Distal hamstring lengthening in cerebral palsy: An evaluation by gait analysis. Int Orthop 1980;3(4): May 2017, Vol 25, No 5 387

8 Total Knee Arthroplasty in Patients With Cerebral Palsy 9. Stout JL, Gage JR, Schwartz MH, Novacheck TF: Distal femoral extension osteotomy and patellar tendon advancement to treat persistent crouch gait in cerebral palsy. J Bone Joint Surg Am 2008;90(11): Raphael BS, Dines JS, Akerman M, Root L: Long-term followup of total hip arthroplasty in patients with cerebral palsy. Clin Orthop Relat Res 2010;468(7): Schroeder K, Hauck C, Wiedenhöfer B, Braatz F, Aldinger PR: Long-term results of hip arthroplasty in ambulatory patients with cerebral palsy. Int Orthop 2010;34(3): Palisano R, Rosenbaum P, Walter S, Russell D, Wood E, Galuppi B: Development and reliability of a system to classify gross motor function in children with cerebral palsy. Dev Med Child Neurol 1997;39(4): Grelsamer RP, Meadows S: The modified Insall-Salvati ratio for assessment of patellar height. Clin Orthop Relat Res 1992;282: Insall JN, Dorr LD, Scott RD, Scott WN: Rationale of the Knee Society clinical rating system. Clin Orthop Relat Res 1989;248: Roos EM, Roos HP, Lohmander LS, Ekdahl C, Beynnon BD: Knee Injury and Osteoarthritis Outcome Score (KOOS): Development of a self-administered outcome measure. J Orthop Sports Phys Ther 1998;28(2): Hoffinger SA, Rab GT, Abou-Ghaida H: Hamstrings in cerebral palsy crouch gait. J Pediatr Orthop 1993;13(6): Rodda JM, Graham HK, Nattrass GR, Galea MP, Baker R, Wolfe R: Correction of severe crouch gait in patients with spastic diplegia with use of multilevel orthopaedic surgery. J Bone Joint Surg Am 2006;88(12): Sheehan FT, Babushkina A, Alter KE: Kinematic determinants of anterior knee pain in cerebral palsy: A case-control study. Arch Phys Med Rehabil 2012;93(8): Senaran H, Holden C, Dabney KW, Miller F: Anterior knee pain in children with cerebral palsy. J Pediatr Orthop 2007;27 (1): Bartlett DJ, Hanna SE, Avery L, Stevenson RD, Galuppi B: Correlates of decline in gross motor capacity in adolescents with cerebral palsy in Gross Motor Function Classification System levels III to V: An exploratory study. Dev Med Child Neurol 2010;52(7):e155-e Jahnsen R, Villien L, Aamodt G, Stanghelle JK, Holm I: Musculoskeletal pain in adults with cerebral palsy compared with the general population. J Rehabil Med 2004;36 (2): Oni OO, Mackenney RP: Total knee replacement in patients with Parkinson s disease. J Bone Joint Surg Br 1985;67(3): Duffy GP, Trousdale RT: Total knee arthroplasty in patients with Parkinson s disease. J Arthroplasty 1996;11(8): Vince KG, Insall JN, Bannerman CE: Total knee arthroplasty in the patient with Parkinson s disease. J Bone Joint Surg Br 1989;71(1): Journal of the American Academy of Orthopaedic Surgeons