Stiffness After Total Knee Arthroplasty: Does Component Alignment Differ in Knees Requiring Manipulation?

Transcription

1 The Journal of Arthroplasty Vol. 28 No Stiffness After Total Knee Arthroplasty: Does Component Alignment Differ in Knees Requiring Manipulation? A Retrospective Cohort Study of 281 Patients Paul Harvie, MRCS(Eng), MD, FRCS(Tr & Orth), James Larkin, MBBS, Matt Scaddan, MBBS, FRACS, Lee M. Longstaff, MA, FRCS, Karen Sloan, MSc, and Richard J. Beaver, FRACS Abstract: This study aims to evaluate component alignment in a large cohort of total knee arthroplasties (TKAs) and ascertain whether alignment in TKAs undergoing postoperative manipulation under anesthetic is significantly different from those achieving good function. A retrospective review of 281 consecutive primary TKAs was performed. All TKAs underwent computed tomographic scanning (Perth computed tomography knee protocol). Of 281 TKAs, 21 (7.4%) underwent manipulation, performed at a mean of 8.1 weeks (range, 3-14 weeks) after surgery. No statistically significant difference was seen between groups for any of 12 parameters of alignment. Postoperative stiffness with the need for manipulation under anesthetic is multifactorial in origin. This study found insufficient evidence to support the theory that component alignment contributes significantly to the etiology of this difficult problem. Keywords: total knee arthroplasty, manipulation under anesthetic, component alignment, Perth CT knee protocol. Crown Copyright 2013 Published by Elsevier Inc. All rights reserved. From the Department of Elective Orthopaedics, Royal Perth Hospital, Perth, Western Australia. Submitted February 22, 2010; accepted March 1, The Conflict of Interest statement associated with this article can be found at Reprint requests: Paul Harvie, MRCS(Eng), MD, FRCS(Tr & Orth), Briar Barn, 1 Poplars Close, Blakesley, NN12 8RW, United, Kingdom. Crown Copyright 2013 Published by Elsevier Inc. All rights reserved / $36.00/0 Total knee arthroplasty (TKA) is a highly effective treatment for the management of pain associated with advance knee arthritis. Achieving a functional range of movement after surgery is important for complete patient satisfaction. Despite increasingly sophisticated implant designs, improved surgical techniques and aggressive physiotherapy regimes postoperative stiffness still occurs, frequently necessitating manipulation under anesthetic. The reported prevalence of postoperative stiffness is variable and depends upon the definition applied, however the most commonly cited prevalence is of the order of 6% to 12% [1], that said prevalences of less that 4% have been quoted in several large series [2-8]. The etiology of postoperative stiffness necessitating manipulation is multifactorial in origin and is classically discussed in terms of preoperative, intraoperative and postoperative factors. Component malalignment is universally cited as an etiological factor [1,3,4,9-12]. The purpose of this study was to evaluate 3-dimensional component alignment in a large cohort of TKAs and ascertain whether alignment in those TKAs with a poor postoperative range of movement necessitating manipulation under anesthetic is significantly different that those which achieve a good functional outcome. This represents the first study of its kind to assess alignment in these cohorts in such a detailed manner. Materials and Methods All TKAs performed at out institution are prospectively monitored for life. Patients are reviewed by physiotherapists, independent of the surgeons who performed surgery both preoperatively and at 6 weeks; 3 and 6 months; and at 1, 2, and 5 years postoperatively (and every 5 years thereafter). Patients are assessed using validated outcome measures (Knee Society Score, Western Ontario and McMaster Universities osteoarthritis index, Short Form SF-36 Health Survey [version 2], and a patient satisfaction score). In addition, at 6 months post surgery, a computed tomographic (CT) 14

2 Stiffness After Total Knee Arthroplasty Harvie et al 15 Table. Alignment Results for Non-Manipulated and Manipulated Knees CT protocol Non-manipulated knees Manipulated Knees 95% CI of the mean parameter a Mean SD Mean SD difference P Coronal fem-tib angle to Sagittal fem-tib angle to Femoral V-V to Femoral flex-ext to Femoral rot (TEA) to Tibial V-V to Post tib slope to Tib rot (TT) to Tib rot (PFC) to Anat axis to Lat tib (mm) to Fem-tib MM to All numerical values expressed in degrees apart from Lat tib which is expressed in mm. Coronal fem-tib angle, coronal femoral tibial angle; Sagittal fem-tib angle, sagittal femoral tibial angle Femoral v-v, varus/valgus alignment of femoral component in coronal plane; Femoral flex-ext, Flexion/extension of femoral component in sagittal plane; Femoral rot (TEA), Rotation of femoral component in axial plane relative to transepicondylar axis; Tibial V-V, varus/valgus alignment of tibial component in coronal plane; Post tib slope, posterior slope of tibial component; Tib rot (TT), rotation of tibial component relative to the tibial tuberosity; Tib rot (PFC), rotation of tibial component relative to the posterior femoral condyles; Anat axis, anatomical axis; Lat tib, lateralization of tibial component; Fem-tib MM, femoral tibial mismatch. a Sign conventions: positive (+) for valgus, flexion, external rotation and posterior slope (-) for varus, extension, internal rotation and anterior slope. scan is performed for each TKA according to the Perth CT knee protocol [13]. This is a validated tool and allows the accurate determination of component alignment in three dimensions (coronal varus/valgus alignment, sagittal flexion/extension and axial external/internal rotation for both femoral and tibial components). A multislice CT scanner takes 2.5-mm contiguous slices from the acetabular roof to the talar dome. Scans are stored and digitally reformatted to produce axial, coronal, and sagittal images. The centre of the femoral head, distal femur, tibial plateau, and ankle joints are identified allowing mechanical and anatomical axes to be determined. Prosthesis alignment is then measured against the mechanical axis in both coronal and sagittal planes. Femoral component rotation is measured relative to the transepicondylar axis with tibial component rotation being measured relative to the tibial tuberosity and the posterior femoral condyles. Coupled femorotibial rotational alignment is assessed by superimposition of the femoral and tibial axial images. This allows visualization of the femorotibial mismatch, which is important because internal rotation of the femoral component can affect patellar tracking. The accuracy of this technique has been validated with the FARO-arm method. All scans were performed at a single radiology centre, performed and reported by a single radiographer. A retrospective review of 281 consecutive Duracon (Stryker Corp, Kalamazoo, Michigan, USA) TKAs performed at our institution was performed. Hospital records were used to identify those patients in this group who underwent formal manipulation under anesthetic. The indication for manipulation as well as timing of manipulation were also noted. All CT scans performed at our institution are stored on a digital Picture Archiving and Communications System. The Perth CT knee results for all 281 patients were retrieved. The alignment for TKAs undergoing manipulation was directly compared with the remainder of TKAs in this cohort that achieve good function and did not require manipulation. Statistical analysis was performed using the SPSS statistical software package (SPSS, Chicago, IL) applying Student t test for parametric data. P b.05 was regarded as statistically significant. Results Two-hundred eighty-one consecutive TKAs performed at our institution were reviewed. Of these 21 TKAs, (7.4%) had undergone manipulation under anesthetic, the remainder achieving an acceptable postoperative range of movement before CT scanning. No evidence of infection was found in any TKA requiring manipulation. Manipulation was performed in a mean of 8.1 weeks (range, 3-14 weeks) after TKA surgery, the sole indication being an unsatisfactory range of movement (mean arc of movement at manipulation being 62 [range 30 to 75 ]) with a mean extension deficit of 8 (range, 5-30 ). Comparison of component alignment was made between the 21 manipulated and 260 nonmanipulated TKAs. No statistically significant difference was seen in component alignment between groups for any of 12 parameters of the Perth CT knee protocol (see Table). At 12 months post-tka, the mean range of movement of knees requiring manipulation was 78 degrees compared with 102 degrees in the non-

3 16 The Journal of Arthroplasty Vol. 28 No. 1 January 2013 manipulated cohort (P b.0001) (corresponding Knee Society scores were 124 and 142, respectively [P =.002]). Postoperative stiffness with the need for manipulation under anesthetic is multifactorial in origin. This study found insufficient evidence to support the theory that component alignment contributes significantly to the etiology of this difficult problem. Discussion The etiology of stiff knees after TKA is multifactorial [1-5,9-12,14-17]. It is likely that more than one factor contributes to the final presentation of the stiff knee. Preoperative range of movement is classically regarded as the most important determinant of final range of movement post TKA [2,3,12], but preoperative range of movement does not necessarily correlate with the severity of degenerative changes seen radiographically, Meding et al confirming no difference in functional outcome with varying severity of radiographic changes [15]. In this study, the detailed 3-dimensional alignment in TKAs with both a good outcome and those requiring manipulation have been compared and no differences have been found between groups. Surgical errors resulting in oversizing of the femoral component (anteriorizing the component and over stuffing the patellofemoral joint) and producing an anteriorly sloped tibial component are well recognized causes of poor flexion post TKA. It is important to differentiate between surgical error producing extremes of component alignment and the subtle variations in 3-dimensional alignment that have been investigated in this study (the former at least an order of magnitude greater in size than the latter). Typically, the aforementioned surgical errors will produce a mechanical block to flexion with no extensor lag [1] (and necessitate revision surgery if good function is to be achieved). The stiff knees progressing to manipulation in this study all presented differently, all having deficits of both flexion and extension. In addition, none of the 21 TKAs manipulated had an oversized femoral or anteriorly sloping tibial component excluding the presence of gross-malalignment due to surgical error. Logic states that any grossly malaligned component (usually obvious radiographically) may result in poor flexion post TKA. It is reasonable to assume that such errors should be avoidable by a proficient high-volume arthroplasty surgeon. Where surgical errors are prevalent, internal audit and change in practice is warranted. Almost universally, the acceptably quoted standard for component alignment in the coronal plane is ±3 to the mechanical axis. Although perpetuated, the source of this standard is infrequently cited. It was initially quoted by Jeffery et al [18] in 1991 and relates to the outcome of 115 Denham total knee replacements (a prosthesis reported by Sikorski as being a very unusual knee design [19]). The prosthesis comprises a tibial component with a removable intramedullary guide and a stemmed femoral component. Furthermore, 3 is an arbitrary figure, and there is no reason to believe that it represents a definitive value for the acceptability of alignment (Sikorski having revised Jeffery's aforementioned estimates to ±2 for most parameters with +1 to 5 used for sagittal tibial alignment [19]). There is unlikely to be such a universal standard for all TKAs, that is, it will vary according to implant and is likely to be broader as prostheses become increasingly engineered. Despite this, ±3 continues to be applied in the research scenario when in fact it probably more accurately represents the reproducibility that the reasonable Fig. 1. Coronal femoral alignment frequency for non-manipulated TKAs.

4 Stiffness After Total Knee Arthroplasty Harvie et al 17 Fig. 2. Sagittal femoral alignment frequency for non-manipulated TKAs. arthroplasty surgeon should be able to achieve by conventional means. Of further note, Jeffery's original work was based only on coronal alignment whereas alignment is a three-dimensional phenomenon expanded up on by Sikorski. Referring to these standards, further evidence as to the multifactorial etiology of the stiff knee is given when looking at component alignment in TKAs with a good functional outcome. When looking specifically at femoral alignment in the coronal and sagittal planes, femoral rotation, and tibial alignment in the coronal and sagittal planes, of 260 TKAs with a good functional outcome, 16%, 35%, 34%, 8% and 32%, respectively, were malaligned in the aforementioned planes (after Sikorski [19], see Figs. 1-5). Malalignment is reduced to 7%, 24%, 24%, and 4%, respectively, in the above planes (with no value for sagittal tibial alignment) if Jeffery's standards are applied in 3 dimensions. Thus, depending on the standards applied, malaligned components can still result in a good functional outcome after TKA; therefore, other factors must play a significant role. The main criticism of this study is that while stating stiffness after TKA is multifactorial, we have looked specifically at one reported etiological factor independently of all others. An attempt at matching cohorts, although feasible, was not undertaken. Many patient Fig. 3. Rotational femoral alignment frequency for non-manipulated TKAs.

5 18 The Journal of Arthroplasty Vol. 28 No. 1 January 2013 Fig. 4. Coronal tibial alignment frequency for non-manipulated TKAs. factors have been reported as contributing to knee stiffness post TKA and include obesity, diabetes mellitus, heterotropic ossification, anticoagulation therapy, inadequate pain management, and poor compliance with physiotherapy [1,4]. Given the highly multifactorial etiology of this condition and the number of patient factors alone, matching of cohorts is highly inaccurate and not feasible. In addition, data relating to many of the known etiological factors (including some of those listed previously) are difficult to extract and evaluate and some have subjective components making analyses difficult. In addition, it is noted from the Table that the difference in coronal and sagittal alignment between study cohorts approaches significance (P =.051 and.053, respectively). Despite this, these values still remain statistically nonsignificant, and an extrapolation towards assumed significance is wrong as they are equally liable to become even more nonsignificant. It is felt therefore that further research with a potentially larger scale study would help declare to which side these results are tending and, thus, confirm of indeed refuting the findings to date. Conversely, and in support of our study methodology, 3-dimensional component alignment is definitive and independent of any other variable once the TKA is implanted. Thus, cohort demographics such as age, sex, and BMI have not been included as they have no bearing on component alignment. In addition, we have used the Fig. 5. Sagittal tibial alignment frequency for non-manipulated TKAs.

6 Stiffness After Total Knee Arthroplasty Harvie et al 19 Perth CT knee protocol, a validated cadaver-based protocol, which is part of the routine prospective lifelong follow-up which all our TKA patients undergo. The Perth CT knee protocol has been used at our institution since its original development, our radiologists being highly experienced in reporting the scans performed supporting the validity of the results obtained and the conclusion drawn from them. In conclusion, it is known that the development of knee stiffness requiring manipulation after total knee arthroplasty is a multifactorial phenomenon. We found no statistically significant differences in 12 parameters of component alignment between TKAs requiring manipulation and those achieving a good functional outcome. In the absence of gross malalignment due to surgical error factors other than component alignment are more important etiological determinants of poor flexion requiring manipulation after TKA. References 1. González Della Valle A, Leali A, Haas S. Etiology and surgical intervention for stiff total knee replacements. Hosp Spec Surg J 2007;3:8. 2. Keating EM, Ritter MA, Harty LD, et al. Manipulation after total knee arthroplasty. J Bone Joint Surg Am 2007;89-A:5. 3. Yercan HS, Sugun TS, Bussiere C, et al. Stiffness after total knee arthroplasty: prevalence, management and outcomes. Knee 2006;13:7. 4. Gandhi R, de Beer J, Leone J, et al. Predictive risk factors for stiff knees in total knee arthroplasty. J Arthroplasty 2006;21:7. 5. Namba RS, Inacio M. Early and late manipulation improve flexion after total knee arthroplasty. J Arthroplasty 2007; 22:4. 6. Scranton Jr PE. Management of knee pain and stiffness after total knee arthroplasty. J Arthroplasty 2001;16:8. 7. Daluga D, Lombardi Jr AV, Mallory TH, et al. Knee manipulation following total knee arthroplasty: Analysis of prognostic variables. J Arthroplasty 1991;6: Mauerhan DR, Mokris JG, Ly A, et al. Relationship between length of stay and manipulation rate after total knee arthroplasty. J Arthroplasty 1998;13:5. 9. Dennis DA, Komistek RD, Scuderi GR, et al. Factors affecting flexion after total knee arthroplasty. Clin Orthop Relat Res 2007;464: Lang JEGC, Aitken GSE, Pietrobon R, et al. Results of contralateral total knee arthroplasty in patients with a history of stiff total knee arthroplasty. J Arthroplasty 2008; 23: Nelson CLKJ, Lotke PA. Stiffness after total knee arthroplasty. J Bone Joint Surg Am 2005;87-A(Supp 1, Part 2): Bong MRDCP. Stiffness after total knee arthroplasty. J Am Acad Ortho Surg 2004;12: Chauhan SKCG, Lloyd S, Scott RG, et al. Computerassisted total knee replacement: A controlled cadaver study using a multi-parameter quantitative CT assessment of alignment (the Perth CT Protocol). J Bone Joint Surg Br 2004;86-B: Massin PLC, Cappelli M, Petit A, et al. Total knee arthroplasty with limitations of flexion. Orthopaedics & Traumatology 2009; Meding JB, Faris PM, Keating EM, et al. Does the preoperative radiographic degree of osteoarthritis correlate to results in primary total knee arthroplasty. J Arthroplasty 2001;16: Kim JNC, Lotke PA. Stiffness after total knee replacement: prevalence of the complication and outcomes of revision. J Bone Joint Surg Am 2004;86-A: Fox JLPR. The role of manipulation following total knee replacement. J Bone Joint Surg Am 1981;63-A: Jeffery RS, Morris RW, Denham RA. Coronal alignment after total knee arthroplasty. J Bone Joint Surg [Br] 1991; 73-B-5: Sikorski JM. Alignment in total knee arthroplasty. J Bone Joint Surg Br 2008;90-B-9:1121.