- Email: [email protected]
Does restoration of leg length and femoral offset play a role in functional outcome one year after hip hemiarthroplasty?
Accepted Manuscript Title: Does restoration of leg length and femoral offset play a role in functional outcome one year after hip hemiarthroplasty? Authors: Dror Lakstein, Ehud Atoun, Orit Wissotzky, Zachary Tan PII: DOI: Reference:
S0020-1383(17)30282-6 http://dx.doi.org/doi:10.1016/j.injury.2017.04.054 JINJ 7219
To appear in:
Injury, Int. J. Care Injured
Accepted date:
25-4-2017
Please cite this article as: Lakstein Dror, Atoun Ehud, Wissotzky Orit, Tan Zachary.Does restoration of leg length and femoral offset play a role in functional outcome one year after hip hemiarthroplasty?.Injury http://dx.doi.org/10.1016/j.injury.2017.04.054 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Does restoration of leg length and femoral offset play a role in functional outcome one year after hip hemiarthroplasty?
Dror Lakstein, MD 1,2 Ehud Atoun, MD 3,4 Orit Wissotzky 1 Zachary Tan, MD 5 1
Sackler school of medicine, Tel-Aviv University, Tel-Aviv, Israel
2
Orthopedic department, E. Wolfson medical center, Holon, Israel, POB 58100
3
Orthopedic department, Barzilai medical center, Ashkelon, Israel
4
Faculty of medicine, Ben-gurion University, Beer-Sheva, Israel
5
Faculty of medicine, University of Toronto, Toronto, ON, Canada Corresponding author: Dror Lakstein Orthopaedic Department, E. Wolfson medical center POB 5, Holon, Israel, 58100 t. ++972-35028383 f. ++972-35028774 [email protected]
1
Abstract Background: The objective of this study was to evaluate the correlation between specific joint biomechanical parameters and 1 year functional outcome scores in elderly patients receiving hemiarthroplasty in the setting of intracapsular hip fractures. Methods: This is a retrospective, institutional registry based study. 168 hip hemarthroplasties were captured from October 2013 to June 2015. Patients were excluded based on contralateral hip surgery, perioperative complications or inadequate radiographs. 84 patients were alive at one year follow up. We compared mobility and pain scores to radiographically determined variations of leg lengths and femoral offset. We also compared the performance of fellowship trained arthroplasty surgeons to their nonfellowship trained counterparts. Results: The operated leg was a mean of 1.12 ± 6.8mm longer than the contralateral. leg length discrepancy (LLD) was less than 10 mm in 72 patients. Mean difference in offset between limbs was 0.25 ± 3.3mm. The difference was within 5mm in 79 patients (94%). We found no statistically significant correlation between mobility or pain scores and variations in leg length or offset. We found significantly better performance of the arthroplasty surgeons in restoring leg length but no difference in offset reconstruction or functional benefit for the patient. Conclusions: Our study was unable to demonstrate a significant relationship between leg length or femoral offset restoration and the patient’s ultimate functional recovery. Arthroplasty surgeons performed better in restoring leg length, but no associated functional advantage was seen. Keywords: Bipolar; hemiarthroplasty; leg length discrepancy,femoral offset
2
Introduction Hip hemiarthroplasty is a common procedure for the treatment of displaced intracapsular hip fractures. It is currently indicated for older, lower demand patients [15]. The treatment ideal is for full rehabilitation and return to the pre-injury functional state. However, only 1 in 3-5 of these patients survives to regain their previous ambulatory status [6-9]. It is well established that the restoration of optimal hip biomechanics is essential in the setting of an elective total hip arthroplasty (THA) [10-12]. Leg length discrepancy (LLD), whether true or apparent, may be readily perceived and can affect patient satisfaction and functional outcomes. Reduced offset may decrease abductor tensioning with a resultant abductor lurch and decreased component stability. Excessive offset and abductor over-tensioning may cause lateral hip pain as well as perceived lengthening of the leg. Mismanagement of length and offset may compromise implant longevity. In elderly patients undergoing hemiarthroplasty, the role of appropriate joint biomechanics in reducing the risk of dislocation is well documented [13,14]. However, the functional effect of length and offset restoration after hemiarthroplasty is less clear. Only a few studies addressed this question with no clear conclusion [15,16]. This study evaluated the relationship between radiographic measures of joint biomechanics and functional outcome in elderly patients undergoing hemiarthroplasty for the treatment of intracapsular hip fractures at one year post-operative. We also examined the relationship between surgeons' Arthroplasty expertise and restoration of leg length, offset and function. Patients and methods
3
This is a retrospective, registry based study, conducted at a level II academic trauma center. We reviewed our prospectively collected institutional hip fracture registry for all hip fracture surgeries performed between October 2013 and June 2015. Overall, 765 patients received an operation for the hip fracture diagnosis during this time period. 168 patients met our inclusion criteria: 1- intracapsular fracture and 2- greater than 60 years old. During the same period, another 60 patients underwent total hip replacements and 28 patients underwent cannulated screws fixation for intracapsular hip fractures. Exclusion criteria included: 1- failure to complete the one year registry follow-up; 2any previous surgery on the contralateral hip; 3- perioperative medical or technical complications that may affect functional outcome and 4- the lack of adequate postoperative pelvic radiographs. Forty five patients (27%) died and 10 other patients were lost to follow-up prior to one year. 16 patients had previous surgeries on the contralateral hip. In 4 cases, adequate radiographs were unavailable. Complications excluding patients from the study included 3 infections (1.7%), 2 dislocations (1.1%), 1 intraoperative fracture of the greater trochanter, 1 sciatic nerve palsy and 1 cerebrovascular accident. 1 patient was also excluded because the hemiarthroplasty was performed with an ipsilateral below knee amputation. Overall, 84 patients (64 females) between the ages of 60 and 95 (mean, 83±7) were included for analysis (figure 1). The study was conducted after appropriate approval from the hospital's Institutional Review Board. All patients underwent cemented bipolar hemiarthroplasty through the posterolateral approach. Surgeries were performed by 13 different staff surgeons, as determined by the call schedule. Versys Heritage Stems (Zimmer, Warsaw, Indiana) with bipolar shells were used in all cases. All hip fractures admitted to our hospital, excluding pediatric and periprosthetic fractures were routinely included in the Institutional Hip 4
Fracture Registry. The registry includes clinical, demographic and radiographic data. We documented preoperative, operative and up to 1 year postoperative functional outcomes and associated complications. Specifically, pain and functional scores were collected preoperatively, at post-operative 1 month, 3 month, and 1 year by a trained research assistant. Determination of mobility scores was via the validated British National Hip Fracture Database Scoring system: 1 - no functional mobility; 2 - some indoor mobility but never goes out without help; 3 - mobile outdoors with a walker; 4 mobile outdoor with a cane; 5 - freely mobile without aids [17]. Pain was graded according to the pain limb of the Merle D'Aubigné Postel system: 0 - intense permanent pain; 1 - severe pain day and night; 2 - severe pain when walking, prevents activity; 3 tolerable pain with limited activity; 4 - mild walking pain; 5 - mild inconsistent pain; 6 - no pain [18]. All patients underwent digital radiography using a standard protocol, including anteroposterior (AP) view of the pelvis on the second postoperative day. The pelvic AP views were taken with the patient supine; the beam centered over the pubis symphysis with both hips internally rotated 10 to 15 degrees to balance physiologic anteversion. Radiographic
measurements
were
performed
using
TraumaCad®
software
(TraumaCad, Petach-Tikva, Israel). Radiographs were calibrated according to the known bipolar shell size. Leg length discrepancy was measured using the designated software tool, based on the vertical distance between a horizontal line connecting both teardrops and the medial apex of lesser trochanters (figure 2) [19]. Femoral offset was measured as the horizontal distance between the hips' center of rotation and the anatomical femoral axis (figure 3) [19]. Statistical analysis
5
The correlation coefficient between the patient’s hip function and pain scores and the radiographic determinants of leg length and offset was obtained with Pearson's correlation. An analysis of the same outcomes comparing patients receiving the operation by arthroplasty fellowship trained surgeons versus their non-fellowship trained counterparts was performed via the student t-test. A P-value of < 0.05 was considered to be statistically significant. Statistical analyses were performed using MedCalc® V6.8 software (MedCalc Software, Mariakerke, Belgium).
Results Mean mobility score was 4.42 ± 0.89 (range, 1-5) preoperatively and 3.26 ± 1.25 at 1 year follow-up. Only 32 patients (38%) attained their preoperative mobility status. Forty one patients (49%) lost one or two mobility levels. Mean postoperative pain score was 5.04 ± 1.1 (range, 0-6). Forty three patients (51%) had no pain and 32 patients (38%) experienced mild inconsistent or walking pain. The operated leg was a mean of 1.12 ± 6.8mm longer than the contralateral. LLD was less than 10mm in 72 patients (85%), defined as optimal leg length restoration. In 9 patients the operated leg was longer by 10-22mm and in 3 patients it was shorter by 1013mm. 7 patients had LLD of 10-15mm (3 shorter and 4 longer) , 6 of which lost 1 level of mobility. Three patients had LLD of 16-22mm or more and lost at least 3 levels of mobility. Mean difference in offset between legs was 0.25 ± 3.3mm. The difference was within 5mm in 79 patients (94%), defined as optimal offset restoration. In 2 patients the operated leg had an 8-9mm increase in offset and a loss of 1-2 levels of mobility. 3 patients had a reduced offset of 7-10mm and a loss of 2-3 levels of mobility.
6
We found no statistically significant correlation between mobility scores, or a combination of pain and mobility scores, and associated LLD or offset difference (Table 1). There was however a trend towards significant between LLD and decrease in mobility scores (Figure 4). 38 patients were operated by fellowship trained Arthroplasty surgeons and 46 were operated by trauma, sports or foot & ankle surgeons. Table 2 demonstrates significantly better performance of the arthroplasty surgeons in restoring leg length but no difference in offset reconstruction or functional outcomes. Discussion Osteoporotic femoral neck fractures in the elderly are common and possess significant implications towards patient morbidity and mortality. Currently, hemiarthroplasties are reserved for the most fragile subgroup of the hip fracture population: low demand individuals with very limited preoperative ambulatory status. While many studies have examined the role of hip biomechanics in the setting of elective hip arthroplasty, the trauma literature is scant at best. Our results demonstrates no significant correlation between restoration of femoral offset, leg length values or surgeon's expertise and the patient’s mobility or pain scores at one year postoperatively. This study has several limitations. Only 50% of the initial cohort was eventually analyzed. However, the total proportions of 27% mortality, 17% with previous surgeries and 4% complications are reasonable heterogeneity figures in any hip fracture cohort. A second limitation is the assessment of femoral offset on plain radiographs. While correction of rotation may be calculated on the operated hip, there is no optimal method to do so on the non-operative hip. CT scans would provide more accurate
7
assessment. A consistent radiographic technique was enforced with both legs 15 degrees internally rotated and exclusion of asymmetrical radiographs. In this study, patient outcomes at 1 year are consistent with findings from previous studies in the literature. 27% of the initial 168 patients died within a year. Only 38% of the patients that survived regained the preoperative function. Other studies consistently demonstrate roughly 30% one year mortality and that one third of the survivors regain the preoperative functional level [7-10]. Rehabilitation achievements of elderly patients after femoral hip fractures are multifactorial and are largely influenced by patients' general medical and mental status. The results of a pain free, stable joint and broadly regaining the preoperative mobility without suffering perioperative complications is considered successful orthopedic treatment. This is in contrast with elective total hip patients who usually have pain and limitations of function preoperatively and expect normal function postoperatively. The elective nature of the total hip replacement for arthritis necessitates closer scrutiny of intraoperative variables contributing to the overall functional outcome profile. Thus, studies evaluating the implications of biomechanical restoration on THA patients' function generally evaluate pain and function with finer detail, depicted in the more comprehensive scoring tools like the Harris hip score or the Womac index. Two studies previously examined the functional outcomes of restoration of hip parameters with hemiarthroplasty. Hartel et al. found no correlation between femoral offset or LLD and functional outcome scores during the first month after surgery [15]. Function and pain during the immediate postoperative phase may not reflect long-term outcome. Buecking et al. examined 60 patients at 12 months after surgery. Femoral offsets measured on postoperative hip radiographs were compared with the contralateral side as measured on preoperative pelvic radiographs. Leg length was not addressed in this study, since postoperative pelvic radiographs were not available. Positive correlation was demonstrated between femoral offset restoration and both the 8
Harris Hip Score and the Instrumental Activities for Daily Living Scale, but not Timed Up and Go measurements [16]. Our study is based on an institutional hip fracture registry and provides several advantages. Firstly, uniform records of both preoperative and postoperative function are available, allowing for analysis of functional loss in this specific low-demand patient population. Secondly, routine postoperative AP pelvis radiographs allowed for measurements of LLD and femoral offset on one radiograph taken with a consistent and reproducible technique. In contrast to hemiarthroplasty, the impact of LLD on functional outcome in THA has been thoroughly studied. LLD may be readily perceived by the patient and may become a cause of litigation. However, conflicting evidence exists regarding the threshold of clinically significant LLD; this may range between 5mm and 2cm [20-22]. Other studies found no clinical significance of LLD after THA [23-25]. Restoration of femoral offset in THA may improve abductor muscle strength, reduce abductor exertion required for walking, improve range of motion, joint stability and reduce joint wear [20, 26-30]. Conversely, reduced femoral offset may decrease abductor strength and increase the incidence of abductor lurch [26,28]. However, some studies demonstrate that increased offset may cause localized trochanteric pain [31]. Other studies found no significant functional implications of reduced or increased offset [31,32]. Conclusion Our study could not demonstrate that restoration of leg length or femoral offset significantly affected patients chance to regain their preoperative level of ambulation or experience pain. Arthroplasty surgeons performed better in restoring leg length with no significant functional advantage. Nevertheless, optimizing joint biomechanics to that of pre-injury anatomic relationships has recognized advantages. Firstly, observing all tenants of maximizing joint stability is paramount in the setting of any hip arthroplasty operation. Secondly, the few outliers in our series had demonstrable poor outcomes. All patients with LLD surpassing 15mm and patients with reduced offset of 5mm or more could not ambulate independently outside the house. Moreover, subtle functional benefits may not be apparent in the functional scores used in this study.
9
References 1. National Institute for Health and Care Excellence (2011). Hip fracture: The management of hip fracture in adults. CG124 (2011). London: National Institute for Health and Care Excellence. 2. Burgers PT, Van Geene AR, Van den Bekerom MP, Van Lieshout EM, Blom B, Aleem IS, Bhandari M, Poolman RW. Total hip arthroplasty versus hemiarthroplasty for displaced femoral neck fractures in the healthy elderly: a meta-analysis and systematic review of randomized trials. Int Orthop. 2012 Aug;36(8):1549-60. 3. Liu Y, Tao X, Wang P, Zhang Z, Zhang W, Qi Q, Meta-analysis of randomised controlled trials comparing unipolar with bipolar hemiarthroplasty for displaced femoral-neck fractures. Int Orthop. 2014 Aug;38(8):1691-6. 4. Bhandari M, Devereaux PJ, Tornetta P 3rd, Swiontkowski MF, Berry DJ, Haidukewych G, Schemitsch EH, Hanson BP, Koval K, Dirschl D, Leece P, Keel M, Petrisor B, Heetveld M, Guyatt GH. Operative management of displaced femoral neck fractures in elderly patients. An international survey. J Bone Joint Surg Am. 2005 Sep;87(9):2122-30. 5. Inngul C, Hedbeck CJ, Blomfeldt R, Lapidus G, Ponzer S, Enocson A. Unipolar hemiarthroplasty versus bipolar hemiarthroplasty in patients with displaced femoral neck fractures: a four-year follow-up of a randomized controlled trial. Int Orthop. 2013 Dec;37(12):2457-64. 6. Vochteloo AJ, Moerman S, Tuinebreijer WE, Maier AB, de Vries MR, Bloem RM, Nelissen RG, Pilot P. More than half of hip fracture patients do not regain mobility in the first postoperative year. Geriatr Gerontol Int 2013; 13: 334–341.
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7. Zhang J, Ang ML, Kwek EB. Who Will Walk Again? Effects of Rehabilitation on the Ambulatory Status in Elderly Patients Undergoing Hemiarthroplasty for Femoral Neck Fracture. Geriatr Orthop Surg Rehabil. 2015 Sep;6(3):168-7. 8. Neuman MD, Silber JH, Magaziner JS, Passarella MA, Mehta S, Werner RM. Survival and functional outcomes after hip fracture among nursing home residents. JAMA Intern Med. 2014 Aug;174(8):1273-80. 9. Brauer CA, Coca-Perraillon M, Cutler DM, Rosen AB. Incidence and mortality of hip fractures in the United States. JAMA. 2009 Oct 14;302(14):1573-9. 10. Lecerf G, Fessy MH, Philippot R. Femoral offset: Anatomical concept, definition, assessment, implications for preoperative templating and hip arthroplasty. Orthop Traumatol Surg Res. 2009 May;95(3):210–219. 11. Rubash HE, Parvataneni HK. The pants too short, the leg too long: leg length inequality after THA. Orthopedics 2007 Sep;30(9):764–765. 12. Flecher X, Ollivier M, Argenson JN. Lower limb length and offset in total hip arthroplasty. Orthop Traumatol Surg Res. 2016 Feb;102(1 Suppl):S9-20. 13. Mukka S, Lindqvist J, Peyda S, Brodén C, Mahmood S, Hassany H, SayedNoor A. Dislocation of bipolar hip hemiarthroplasty through a postero-lateral approach for femoral neck fractures: A cohort study. Int Orthop. 2015 Jul;39(7):1277-82. 14. Madanat R, Mäkinen TJ, Ovaska MT, Soiva M, Vahlberg T, Haapala J. Dislocation of hip hemiarthroplasty following posterolateral surgical approach: a nested case-control study. Int Orthop. 2012 May;36(5):935-40. 15. Hartel M1, Arndt M, Eulenburg CZ, Petersen JP, Rueger JM, Hoffmann M. Restoration of hip architecture with bipolar hemiarthroplasty in the elderly: does
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it affect early functional outcome? Arch Orthop Trauma Surg. 2014 Jan;134(1):31-8. 16. Buecking B, Boese CK, Bergmeister VA, Frink M, Ruchholtz S, Lechler P. Functional implications of femoral offset following hemiarthroplasty for displaced femoral neck fracture. Int Orthop. 2016 Jul;40(7):1515-21. 17. http://www.nhfd.co.uk. Last visited August 25, 2016 18. D'aubigne RM, Postel M. Functional results of hip arthroplasty with acrylic prosthesis. J Bone Joint Surg Am. 1954 Jun;36-A(3):451-75. 19. Kwok IH, Pallett SJ, Massa E, Cundall-Curry D, Loeffler MD. Pre-operative digital templating in cemented hip hemiarthroplasty for neck of femur fractures. Injury. 2016 Mar;47(3):733-6. 20. Clement ND, S Patrick-Patel R, MacDonald D, Breusch SJ. Total hip replacement: increasing femoral offset improves functional outcome. Arch Orthop Trauma Surg. 2016 Sep;136(9):1317-23 21. Konyves A, Bannister GC. The importance of leg length discrepancy after total hip arthroplasty. J Bone Joint Surg Br. 2005 Feb;87(2):155-7. 22. Sykes A, Hill J, Orr J, Humphreys P, Rooney A, Morrow E, Beverland D (2015) Patients’ perception of leg length discrepancy post total hip arthroplasty. Hip Int 25:452–456 23. White TO, Dougall TW (2002) Arthroplasty of the hip. Leg length is not important. J Bone Jt Surg Br 84:335–338 24. Kersic M, Dolinar D, Antolic V, Mavcic B (2014) The impact of leg length discrepancy on clinical outcome of total hip arthroplasty: comparison of four measurement methods. J Arthroplast 29:137–141
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25. Whitehouse MR, Stefanovich-Lawbuary NS, Brunton LR, Blom AW (2013) The impact of leg length discrepancy on patient satisfaction and functional outcome following total hip arthroplasty. J Arthroplast 28:1408–1414 26. Cassidy KA, Noticewala MS, Macaulay W, Lee JH, Geller JA. Effect of femoral offset on pain and function after total hip arthroplasty. J Arthroplasty. 2012 Dec;27(10):1863-9. 27. Asayama I, Naito M, Fujisawa M, Kambe T. Relationship between radiographic measurements of reconstructed hip joint position and the Trendelenburg sign. J Arthroplasty. 2002 Sep;17(6):747-51. 28. Asayama I, Chamnongkich S, Simpson KJ, Kinsey TL, Mahoney OM. Reconstructed hip joint position and abductor muscle strength after total hip arthroplasty. J Arthroplasty. 2005 Jun;20(4):414-20. 29. Sakalkale DP, Sharkey PF, Eng K, Hozack WJ, Rothman RH. Effect of femoral component offset on polyethylene wear in total hip arthroplasty. Clin Orthop Relat Res. 2001 Jul;(388):125-34. 30. Mahmood SS, Mukka SS, Crnalic S, Wretenberg P, Sayed-Noor AS. Association between changes in global femoral offset after total hip arthroplasty and function, quality of life, and abductor muscle strength. A prospective cohort study of 222 patients. Acta Orthop. 2016 Feb;87(1):36-41. 31. Liebs TR, Nasser L, Herzberg W, Rüther W, Hassenpflug J. The influence of femoral offset on health-related quality of life after total hip replacement. Bone Joint J. 2014 Jan;96-B(1):36-42. 32. Müller M, Abdel MP, Wassilew GI, Duda G1, Perka C. Do post-operative changes of neck-shaft angle and femoral component anteversion have an effect on clinical outcome following uncemented total hip arthroplasty? Bone Joint J. 2015 Dec;97B(12):1615-22
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Figure 1. Flow diagram for patients included
14
Figure 2. Limb length is measured as the vertical distance between a horizontal and the most prominent point of the lesser trochanter. The operated leg is 2mm longer.
15
Figure 3. Femoral offset is measured as the horizontal distance between the center of the femoral head or the bipolar shell and the axis of the femur. The right femoral offset is 2mm larger.
16
Figure 4. A scatter diagram demonstrating no significant correlation between LLD and loss of mobility status (P=0.08).
17
Table 1. r* -0.02 0.17 0.02 0.18
Pain and mobility Vs. offset difference Pain and mobility Vs. LLD Mobility Vs. offset difference Mobility Vs. LLD * Spearman's correlation coefficient
The correlation between functional outcome and biomechanical restoration
18
P-value 0.84 0.11 0.83 0.08
Table 2.
LLD Offset difference Loss of mobility level Pain score
Arthroplasty surgeons 3.26±2.94 -0.53±3.53 1.1±1.16 5.16±1.08
Other surgeons 6.57±5.25 -0.02±3.22 1.2±1.26 4.93±1.27
P value 0.0009 0.49 0.73 0.39
Comparison of biomechanical restoration and functional outcome of patients operated by arthroplasty surgeons and other surgeons
19
S0020-1383(17)30282-6 http://dx.doi.org/doi:10.1016/j.injury.2017.04.054 JINJ 7219
To appear in:
Injury, Int. J. Care Injured
Accepted date:
25-4-2017
Please cite this article as: Lakstein Dror, Atoun Ehud, Wissotzky Orit, Tan Zachary.Does restoration of leg length and femoral offset play a role in functional outcome one year after hip hemiarthroplasty?.Injury http://dx.doi.org/10.1016/j.injury.2017.04.054 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Does restoration of leg length and femoral offset play a role in functional outcome one year after hip hemiarthroplasty?
Dror Lakstein, MD 1,2 Ehud Atoun, MD 3,4 Orit Wissotzky 1 Zachary Tan, MD 5 1
Sackler school of medicine, Tel-Aviv University, Tel-Aviv, Israel
2
Orthopedic department, E. Wolfson medical center, Holon, Israel, POB 58100
3
Orthopedic department, Barzilai medical center, Ashkelon, Israel
4
Faculty of medicine, Ben-gurion University, Beer-Sheva, Israel
5
Faculty of medicine, University of Toronto, Toronto, ON, Canada Corresponding author: Dror Lakstein Orthopaedic Department, E. Wolfson medical center POB 5, Holon, Israel, 58100 t. ++972-35028383 f. ++972-35028774 [email protected]
1
Abstract Background: The objective of this study was to evaluate the correlation between specific joint biomechanical parameters and 1 year functional outcome scores in elderly patients receiving hemiarthroplasty in the setting of intracapsular hip fractures. Methods: This is a retrospective, institutional registry based study. 168 hip hemarthroplasties were captured from October 2013 to June 2015. Patients were excluded based on contralateral hip surgery, perioperative complications or inadequate radiographs. 84 patients were alive at one year follow up. We compared mobility and pain scores to radiographically determined variations of leg lengths and femoral offset. We also compared the performance of fellowship trained arthroplasty surgeons to their nonfellowship trained counterparts. Results: The operated leg was a mean of 1.12 ± 6.8mm longer than the contralateral. leg length discrepancy (LLD) was less than 10 mm in 72 patients. Mean difference in offset between limbs was 0.25 ± 3.3mm. The difference was within 5mm in 79 patients (94%). We found no statistically significant correlation between mobility or pain scores and variations in leg length or offset. We found significantly better performance of the arthroplasty surgeons in restoring leg length but no difference in offset reconstruction or functional benefit for the patient. Conclusions: Our study was unable to demonstrate a significant relationship between leg length or femoral offset restoration and the patient’s ultimate functional recovery. Arthroplasty surgeons performed better in restoring leg length, but no associated functional advantage was seen. Keywords: Bipolar; hemiarthroplasty; leg length discrepancy,femoral offset
2
Introduction Hip hemiarthroplasty is a common procedure for the treatment of displaced intracapsular hip fractures. It is currently indicated for older, lower demand patients [15]. The treatment ideal is for full rehabilitation and return to the pre-injury functional state. However, only 1 in 3-5 of these patients survives to regain their previous ambulatory status [6-9]. It is well established that the restoration of optimal hip biomechanics is essential in the setting of an elective total hip arthroplasty (THA) [10-12]. Leg length discrepancy (LLD), whether true or apparent, may be readily perceived and can affect patient satisfaction and functional outcomes. Reduced offset may decrease abductor tensioning with a resultant abductor lurch and decreased component stability. Excessive offset and abductor over-tensioning may cause lateral hip pain as well as perceived lengthening of the leg. Mismanagement of length and offset may compromise implant longevity. In elderly patients undergoing hemiarthroplasty, the role of appropriate joint biomechanics in reducing the risk of dislocation is well documented [13,14]. However, the functional effect of length and offset restoration after hemiarthroplasty is less clear. Only a few studies addressed this question with no clear conclusion [15,16]. This study evaluated the relationship between radiographic measures of joint biomechanics and functional outcome in elderly patients undergoing hemiarthroplasty for the treatment of intracapsular hip fractures at one year post-operative. We also examined the relationship between surgeons' Arthroplasty expertise and restoration of leg length, offset and function. Patients and methods
3
This is a retrospective, registry based study, conducted at a level II academic trauma center. We reviewed our prospectively collected institutional hip fracture registry for all hip fracture surgeries performed between October 2013 and June 2015. Overall, 765 patients received an operation for the hip fracture diagnosis during this time period. 168 patients met our inclusion criteria: 1- intracapsular fracture and 2- greater than 60 years old. During the same period, another 60 patients underwent total hip replacements and 28 patients underwent cannulated screws fixation for intracapsular hip fractures. Exclusion criteria included: 1- failure to complete the one year registry follow-up; 2any previous surgery on the contralateral hip; 3- perioperative medical or technical complications that may affect functional outcome and 4- the lack of adequate postoperative pelvic radiographs. Forty five patients (27%) died and 10 other patients were lost to follow-up prior to one year. 16 patients had previous surgeries on the contralateral hip. In 4 cases, adequate radiographs were unavailable. Complications excluding patients from the study included 3 infections (1.7%), 2 dislocations (1.1%), 1 intraoperative fracture of the greater trochanter, 1 sciatic nerve palsy and 1 cerebrovascular accident. 1 patient was also excluded because the hemiarthroplasty was performed with an ipsilateral below knee amputation. Overall, 84 patients (64 females) between the ages of 60 and 95 (mean, 83±7) were included for analysis (figure 1). The study was conducted after appropriate approval from the hospital's Institutional Review Board. All patients underwent cemented bipolar hemiarthroplasty through the posterolateral approach. Surgeries were performed by 13 different staff surgeons, as determined by the call schedule. Versys Heritage Stems (Zimmer, Warsaw, Indiana) with bipolar shells were used in all cases. All hip fractures admitted to our hospital, excluding pediatric and periprosthetic fractures were routinely included in the Institutional Hip 4
Fracture Registry. The registry includes clinical, demographic and radiographic data. We documented preoperative, operative and up to 1 year postoperative functional outcomes and associated complications. Specifically, pain and functional scores were collected preoperatively, at post-operative 1 month, 3 month, and 1 year by a trained research assistant. Determination of mobility scores was via the validated British National Hip Fracture Database Scoring system: 1 - no functional mobility; 2 - some indoor mobility but never goes out without help; 3 - mobile outdoors with a walker; 4 mobile outdoor with a cane; 5 - freely mobile without aids [17]. Pain was graded according to the pain limb of the Merle D'Aubigné Postel system: 0 - intense permanent pain; 1 - severe pain day and night; 2 - severe pain when walking, prevents activity; 3 tolerable pain with limited activity; 4 - mild walking pain; 5 - mild inconsistent pain; 6 - no pain [18]. All patients underwent digital radiography using a standard protocol, including anteroposterior (AP) view of the pelvis on the second postoperative day. The pelvic AP views were taken with the patient supine; the beam centered over the pubis symphysis with both hips internally rotated 10 to 15 degrees to balance physiologic anteversion. Radiographic
measurements
were
performed
using
TraumaCad®
software
(TraumaCad, Petach-Tikva, Israel). Radiographs were calibrated according to the known bipolar shell size. Leg length discrepancy was measured using the designated software tool, based on the vertical distance between a horizontal line connecting both teardrops and the medial apex of lesser trochanters (figure 2) [19]. Femoral offset was measured as the horizontal distance between the hips' center of rotation and the anatomical femoral axis (figure 3) [19]. Statistical analysis
5
The correlation coefficient between the patient’s hip function and pain scores and the radiographic determinants of leg length and offset was obtained with Pearson's correlation. An analysis of the same outcomes comparing patients receiving the operation by arthroplasty fellowship trained surgeons versus their non-fellowship trained counterparts was performed via the student t-test. A P-value of < 0.05 was considered to be statistically significant. Statistical analyses were performed using MedCalc® V6.8 software (MedCalc Software, Mariakerke, Belgium).
Results Mean mobility score was 4.42 ± 0.89 (range, 1-5) preoperatively and 3.26 ± 1.25 at 1 year follow-up. Only 32 patients (38%) attained their preoperative mobility status. Forty one patients (49%) lost one or two mobility levels. Mean postoperative pain score was 5.04 ± 1.1 (range, 0-6). Forty three patients (51%) had no pain and 32 patients (38%) experienced mild inconsistent or walking pain. The operated leg was a mean of 1.12 ± 6.8mm longer than the contralateral. LLD was less than 10mm in 72 patients (85%), defined as optimal leg length restoration. In 9 patients the operated leg was longer by 10-22mm and in 3 patients it was shorter by 1013mm. 7 patients had LLD of 10-15mm (3 shorter and 4 longer) , 6 of which lost 1 level of mobility. Three patients had LLD of 16-22mm or more and lost at least 3 levels of mobility. Mean difference in offset between legs was 0.25 ± 3.3mm. The difference was within 5mm in 79 patients (94%), defined as optimal offset restoration. In 2 patients the operated leg had an 8-9mm increase in offset and a loss of 1-2 levels of mobility. 3 patients had a reduced offset of 7-10mm and a loss of 2-3 levels of mobility.
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We found no statistically significant correlation between mobility scores, or a combination of pain and mobility scores, and associated LLD or offset difference (Table 1). There was however a trend towards significant between LLD and decrease in mobility scores (Figure 4). 38 patients were operated by fellowship trained Arthroplasty surgeons and 46 were operated by trauma, sports or foot & ankle surgeons. Table 2 demonstrates significantly better performance of the arthroplasty surgeons in restoring leg length but no difference in offset reconstruction or functional outcomes. Discussion Osteoporotic femoral neck fractures in the elderly are common and possess significant implications towards patient morbidity and mortality. Currently, hemiarthroplasties are reserved for the most fragile subgroup of the hip fracture population: low demand individuals with very limited preoperative ambulatory status. While many studies have examined the role of hip biomechanics in the setting of elective hip arthroplasty, the trauma literature is scant at best. Our results demonstrates no significant correlation between restoration of femoral offset, leg length values or surgeon's expertise and the patient’s mobility or pain scores at one year postoperatively. This study has several limitations. Only 50% of the initial cohort was eventually analyzed. However, the total proportions of 27% mortality, 17% with previous surgeries and 4% complications are reasonable heterogeneity figures in any hip fracture cohort. A second limitation is the assessment of femoral offset on plain radiographs. While correction of rotation may be calculated on the operated hip, there is no optimal method to do so on the non-operative hip. CT scans would provide more accurate
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assessment. A consistent radiographic technique was enforced with both legs 15 degrees internally rotated and exclusion of asymmetrical radiographs. In this study, patient outcomes at 1 year are consistent with findings from previous studies in the literature. 27% of the initial 168 patients died within a year. Only 38% of the patients that survived regained the preoperative function. Other studies consistently demonstrate roughly 30% one year mortality and that one third of the survivors regain the preoperative functional level [7-10]. Rehabilitation achievements of elderly patients after femoral hip fractures are multifactorial and are largely influenced by patients' general medical and mental status. The results of a pain free, stable joint and broadly regaining the preoperative mobility without suffering perioperative complications is considered successful orthopedic treatment. This is in contrast with elective total hip patients who usually have pain and limitations of function preoperatively and expect normal function postoperatively. The elective nature of the total hip replacement for arthritis necessitates closer scrutiny of intraoperative variables contributing to the overall functional outcome profile. Thus, studies evaluating the implications of biomechanical restoration on THA patients' function generally evaluate pain and function with finer detail, depicted in the more comprehensive scoring tools like the Harris hip score or the Womac index. Two studies previously examined the functional outcomes of restoration of hip parameters with hemiarthroplasty. Hartel et al. found no correlation between femoral offset or LLD and functional outcome scores during the first month after surgery [15]. Function and pain during the immediate postoperative phase may not reflect long-term outcome. Buecking et al. examined 60 patients at 12 months after surgery. Femoral offsets measured on postoperative hip radiographs were compared with the contralateral side as measured on preoperative pelvic radiographs. Leg length was not addressed in this study, since postoperative pelvic radiographs were not available. Positive correlation was demonstrated between femoral offset restoration and both the 8
Harris Hip Score and the Instrumental Activities for Daily Living Scale, but not Timed Up and Go measurements [16]. Our study is based on an institutional hip fracture registry and provides several advantages. Firstly, uniform records of both preoperative and postoperative function are available, allowing for analysis of functional loss in this specific low-demand patient population. Secondly, routine postoperative AP pelvis radiographs allowed for measurements of LLD and femoral offset on one radiograph taken with a consistent and reproducible technique. In contrast to hemiarthroplasty, the impact of LLD on functional outcome in THA has been thoroughly studied. LLD may be readily perceived by the patient and may become a cause of litigation. However, conflicting evidence exists regarding the threshold of clinically significant LLD; this may range between 5mm and 2cm [20-22]. Other studies found no clinical significance of LLD after THA [23-25]. Restoration of femoral offset in THA may improve abductor muscle strength, reduce abductor exertion required for walking, improve range of motion, joint stability and reduce joint wear [20, 26-30]. Conversely, reduced femoral offset may decrease abductor strength and increase the incidence of abductor lurch [26,28]. However, some studies demonstrate that increased offset may cause localized trochanteric pain [31]. Other studies found no significant functional implications of reduced or increased offset [31,32]. Conclusion Our study could not demonstrate that restoration of leg length or femoral offset significantly affected patients chance to regain their preoperative level of ambulation or experience pain. Arthroplasty surgeons performed better in restoring leg length with no significant functional advantage. Nevertheless, optimizing joint biomechanics to that of pre-injury anatomic relationships has recognized advantages. Firstly, observing all tenants of maximizing joint stability is paramount in the setting of any hip arthroplasty operation. Secondly, the few outliers in our series had demonstrable poor outcomes. All patients with LLD surpassing 15mm and patients with reduced offset of 5mm or more could not ambulate independently outside the house. Moreover, subtle functional benefits may not be apparent in the functional scores used in this study.
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References 1. National Institute for Health and Care Excellence (2011). Hip fracture: The management of hip fracture in adults. CG124 (2011). London: National Institute for Health and Care Excellence. 2. Burgers PT, Van Geene AR, Van den Bekerom MP, Van Lieshout EM, Blom B, Aleem IS, Bhandari M, Poolman RW. Total hip arthroplasty versus hemiarthroplasty for displaced femoral neck fractures in the healthy elderly: a meta-analysis and systematic review of randomized trials. Int Orthop. 2012 Aug;36(8):1549-60. 3. Liu Y, Tao X, Wang P, Zhang Z, Zhang W, Qi Q, Meta-analysis of randomised controlled trials comparing unipolar with bipolar hemiarthroplasty for displaced femoral-neck fractures. Int Orthop. 2014 Aug;38(8):1691-6. 4. Bhandari M, Devereaux PJ, Tornetta P 3rd, Swiontkowski MF, Berry DJ, Haidukewych G, Schemitsch EH, Hanson BP, Koval K, Dirschl D, Leece P, Keel M, Petrisor B, Heetveld M, Guyatt GH. Operative management of displaced femoral neck fractures in elderly patients. An international survey. J Bone Joint Surg Am. 2005 Sep;87(9):2122-30. 5. Inngul C, Hedbeck CJ, Blomfeldt R, Lapidus G, Ponzer S, Enocson A. Unipolar hemiarthroplasty versus bipolar hemiarthroplasty in patients with displaced femoral neck fractures: a four-year follow-up of a randomized controlled trial. Int Orthop. 2013 Dec;37(12):2457-64. 6. Vochteloo AJ, Moerman S, Tuinebreijer WE, Maier AB, de Vries MR, Bloem RM, Nelissen RG, Pilot P. More than half of hip fracture patients do not regain mobility in the first postoperative year. Geriatr Gerontol Int 2013; 13: 334–341.
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7. Zhang J, Ang ML, Kwek EB. Who Will Walk Again? Effects of Rehabilitation on the Ambulatory Status in Elderly Patients Undergoing Hemiarthroplasty for Femoral Neck Fracture. Geriatr Orthop Surg Rehabil. 2015 Sep;6(3):168-7. 8. Neuman MD, Silber JH, Magaziner JS, Passarella MA, Mehta S, Werner RM. Survival and functional outcomes after hip fracture among nursing home residents. JAMA Intern Med. 2014 Aug;174(8):1273-80. 9. Brauer CA, Coca-Perraillon M, Cutler DM, Rosen AB. Incidence and mortality of hip fractures in the United States. JAMA. 2009 Oct 14;302(14):1573-9. 10. Lecerf G, Fessy MH, Philippot R. Femoral offset: Anatomical concept, definition, assessment, implications for preoperative templating and hip arthroplasty. Orthop Traumatol Surg Res. 2009 May;95(3):210–219. 11. Rubash HE, Parvataneni HK. The pants too short, the leg too long: leg length inequality after THA. Orthopedics 2007 Sep;30(9):764–765. 12. Flecher X, Ollivier M, Argenson JN. Lower limb length and offset in total hip arthroplasty. Orthop Traumatol Surg Res. 2016 Feb;102(1 Suppl):S9-20. 13. Mukka S, Lindqvist J, Peyda S, Brodén C, Mahmood S, Hassany H, SayedNoor A. Dislocation of bipolar hip hemiarthroplasty through a postero-lateral approach for femoral neck fractures: A cohort study. Int Orthop. 2015 Jul;39(7):1277-82. 14. Madanat R, Mäkinen TJ, Ovaska MT, Soiva M, Vahlberg T, Haapala J. Dislocation of hip hemiarthroplasty following posterolateral surgical approach: a nested case-control study. Int Orthop. 2012 May;36(5):935-40. 15. Hartel M1, Arndt M, Eulenburg CZ, Petersen JP, Rueger JM, Hoffmann M. Restoration of hip architecture with bipolar hemiarthroplasty in the elderly: does
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it affect early functional outcome? Arch Orthop Trauma Surg. 2014 Jan;134(1):31-8. 16. Buecking B, Boese CK, Bergmeister VA, Frink M, Ruchholtz S, Lechler P. Functional implications of femoral offset following hemiarthroplasty for displaced femoral neck fracture. Int Orthop. 2016 Jul;40(7):1515-21. 17. http://www.nhfd.co.uk. Last visited August 25, 2016 18. D'aubigne RM, Postel M. Functional results of hip arthroplasty with acrylic prosthesis. J Bone Joint Surg Am. 1954 Jun;36-A(3):451-75. 19. Kwok IH, Pallett SJ, Massa E, Cundall-Curry D, Loeffler MD. Pre-operative digital templating in cemented hip hemiarthroplasty for neck of femur fractures. Injury. 2016 Mar;47(3):733-6. 20. Clement ND, S Patrick-Patel R, MacDonald D, Breusch SJ. Total hip replacement: increasing femoral offset improves functional outcome. Arch Orthop Trauma Surg. 2016 Sep;136(9):1317-23 21. Konyves A, Bannister GC. The importance of leg length discrepancy after total hip arthroplasty. J Bone Joint Surg Br. 2005 Feb;87(2):155-7. 22. Sykes A, Hill J, Orr J, Humphreys P, Rooney A, Morrow E, Beverland D (2015) Patients’ perception of leg length discrepancy post total hip arthroplasty. Hip Int 25:452–456 23. White TO, Dougall TW (2002) Arthroplasty of the hip. Leg length is not important. J Bone Jt Surg Br 84:335–338 24. Kersic M, Dolinar D, Antolic V, Mavcic B (2014) The impact of leg length discrepancy on clinical outcome of total hip arthroplasty: comparison of four measurement methods. J Arthroplast 29:137–141
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25. Whitehouse MR, Stefanovich-Lawbuary NS, Brunton LR, Blom AW (2013) The impact of leg length discrepancy on patient satisfaction and functional outcome following total hip arthroplasty. J Arthroplast 28:1408–1414 26. Cassidy KA, Noticewala MS, Macaulay W, Lee JH, Geller JA. Effect of femoral offset on pain and function after total hip arthroplasty. J Arthroplasty. 2012 Dec;27(10):1863-9. 27. Asayama I, Naito M, Fujisawa M, Kambe T. Relationship between radiographic measurements of reconstructed hip joint position and the Trendelenburg sign. J Arthroplasty. 2002 Sep;17(6):747-51. 28. Asayama I, Chamnongkich S, Simpson KJ, Kinsey TL, Mahoney OM. Reconstructed hip joint position and abductor muscle strength after total hip arthroplasty. J Arthroplasty. 2005 Jun;20(4):414-20. 29. Sakalkale DP, Sharkey PF, Eng K, Hozack WJ, Rothman RH. Effect of femoral component offset on polyethylene wear in total hip arthroplasty. Clin Orthop Relat Res. 2001 Jul;(388):125-34. 30. Mahmood SS, Mukka SS, Crnalic S, Wretenberg P, Sayed-Noor AS. Association between changes in global femoral offset after total hip arthroplasty and function, quality of life, and abductor muscle strength. A prospective cohort study of 222 patients. Acta Orthop. 2016 Feb;87(1):36-41. 31. Liebs TR, Nasser L, Herzberg W, Rüther W, Hassenpflug J. The influence of femoral offset on health-related quality of life after total hip replacement. Bone Joint J. 2014 Jan;96-B(1):36-42. 32. Müller M, Abdel MP, Wassilew GI, Duda G1, Perka C. Do post-operative changes of neck-shaft angle and femoral component anteversion have an effect on clinical outcome following uncemented total hip arthroplasty? Bone Joint J. 2015 Dec;97B(12):1615-22
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Figure 1. Flow diagram for patients included
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Figure 2. Limb length is measured as the vertical distance between a horizontal and the most prominent point of the lesser trochanter. The operated leg is 2mm longer.
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Figure 3. Femoral offset is measured as the horizontal distance between the center of the femoral head or the bipolar shell and the axis of the femur. The right femoral offset is 2mm larger.
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Figure 4. A scatter diagram demonstrating no significant correlation between LLD and loss of mobility status (P=0.08).
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Table 1. r* -0.02 0.17 0.02 0.18
Pain and mobility Vs. offset difference Pain and mobility Vs. LLD Mobility Vs. offset difference Mobility Vs. LLD * Spearman's correlation coefficient
The correlation between functional outcome and biomechanical restoration
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P-value 0.84 0.11 0.83 0.08
Table 2.
LLD Offset difference Loss of mobility level Pain score
Arthroplasty surgeons 3.26±2.94 -0.53±3.53 1.1±1.16 5.16±1.08
Other surgeons 6.57±5.25 -0.02±3.22 1.2±1.26 4.93±1.27
P value 0.0009 0.49 0.73 0.39
Comparison of biomechanical restoration and functional outcome of patients operated by arthroplasty surgeons and other surgeons
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