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Functional and clinical outcomes of total ankle arthroplasty in elderly compared to younger patients
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Functional and clinical outcomes of total ankle arthroplasty in elderly compared to younger patients$,$$ Shay Tenenbaum, MDa,* , Jason Bariteau, MDb , Scott Coleman, MS, MBAc , James Brodsky, MDc a b c
Department of Orthopedic Surgery, Chaim Sheba Medical Center at Tel HaShomer, Affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Israel Department of Orthopedic Surgery, Emory University School of Medicine, Atlanta, GA, USA Department of Orthopedic Surgery, Baylor University Medical Center, Dallas, TX, USA
A R T I C L E I N F O
A B S T R A C T
Article history: Received 16 August 2016 Received in revised form 27 September 2016 Accepted 30 September 2016 Available online xxx
Background: Total ankle arthroplasty (TAA) is becoming an increasingly utilized procedure for the management of end-stage ankle arthritis. Elderly patients are the fastest growing segment of the population in the western world, creating a unique challenge to the health economics of our era. Determining if elderly patients with end-stage ankle arthritis demonstrate the same improvements in clinical outcomes and functional measures of gait following TAA would be valuable. This can aid to evaluate the utilization of TAA in this enlarging cohort of our population. Methods: Consecutive series of twenty-one patients over the age of 70, who underwent TAA for end-stage ankle arthritis, was prospectively compared to a series of twenty-one patients aged 50–60, who underwent the same procedure by single surgeon during same time period. Clinical outcomes were measured with outcome scores including VAS pain score, AOFAS Ankle and Hindfoot Score, and the SF-36. Three-dimensional gait analysis was performed preoperatively and at a minimum of one year postoperatively, to measure temporal-spatial, kinematic, and kinetic parameters of gait. Mixed model multivariate statistical analysis was used to evaluate and compare the independent contributions to outcomes of the surgical intervention over time; of patient age; and of time-plus-age interaction, as these influenced both the clinical outcomes and the functional gait outcomes. Results: Statistically significant improvements in VAS pain scores, AOFAS ankle/hindfoot scores, and SF36 scores were demonstrated in both age groups. Following surgery, there were improvements in all parameters of gait, including temporal-spatial parameters as step length and walking velocity; kinematic parameters, including, increase in total range of motion to a total of 17–19 ; and kinetic parameters, including increase in ankle power and moment. The improvements both in clinical and gait outcomes were equivalent in the two age groups. Conclusions: In this comparative study, it is shown that both elderly patients over the age of 70 and younger patients aged 50–60 demonstrated equivalent improvements clinical and gait outcomes following ankle arthroplasty. This may be important data both for clinical decision-making and the health economics for our ageing population. ã 2016 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
Keywords: Geriatric Total ankle replacement Gait study
1. Introduction Total ankle arthroplasty is gaining popularity as treatment for end-stage ankle arthritis. Multiple authors, using a range of
$ An investigation of the Human Motion and Performance Laboratory of Baylor University Medical Center, Dallas, Texas. $$ Level of evidence: Level 3, retrospective cohort. * Corresponding author. E-mail address: [email protected] (S. Tenenbaum).
different prostheses, have reported encouraging clinical results following total ankle arthroplasty with improved function and significant pain reduction [1–16]. In addition to positive clinical outcomes, multiple studies have documented functional improvement, as measured by improvements in gait following total ankle arthroplasty. Recent gait studies have shown that ankle arthroplasty significantly produces improved gait compared with preoperative gait, even though does not restore gait to the level normal controls [5,12,13,17–24].
http://dx.doi.org/10.1016/j.fas.2016.09.005 1268-7731/ã 2016 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: S. Tenenbaum, et al., Functional and clinical outcomes of total ankle arthroplasty in elderly compared to younger patients, Foot Ankle Surg (2016), http://dx.doi.org/10.1016/j.fas.2016.09.005
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Ankle arthroplasty has been shown to produce increased joint movement, improved symmetry of gait, and restoration of a more normal pattern of ground reaction force [17,22,23,25–28]. Elderly patients are the fastest growing segment of the population in the western world, creating a unique challenge to the health economics of our era [29]. Determining if elderly patients with end-stage ankle arthritis demonstrate the same improvements in clinical outcomes and in functional measures of gait following TAA would be valuable to determine the appropriate utilization of this procedure in this enlarging cohort of our population. Strasser and Turner [30] retrospectively studied ankle arthrodesis outcomes in elderly patients over the age of 70. Authors showed, functional outcomes measured with FAAM and AOFAS scores to be satisfactory, and union rate to be comparable with previous reports for younger patients. Authors concluded that ankle arthrodesis is an effective surgical treatment option in an elderly patient population. However, it is yet undetermined whether elderly patients with end-stage ankle arthritis experience the same clinical and functional improvements produced by ankle arthroplasty as younger patients. Only a handful of studies addressed the performance of patients undergoing total ankle arthroplasty according to patients’ age. These studies focused mainly, on complications, implant survival and revision rates [31–33]. Fevang et al. [33] showed age did not influence revision rates. Conversely, Henricson et al. [32] showed that a lower age at time of index surgery implied increased risk for revision. Spirt et al. [31] reported that patients under the age of 54 who underwent TAA had a 1.45-times greater risk of reoperation and a 2.65-times greater risk of implant failure than older patients. A recent study [34] examined the effect of age on total ankle arthroplasty on patient-reported outcomes. Authors showed that younger patients had similar clinical outcomes as older patients in early followup. However, no functional measurements such as gait analysis were utilized. Kofoed and Lundberg-Jensen [9] retrospectively, reported on 100 patients treated with total ankle arthroplasty for osteoarthritis or rheumatoid arthritis of the ankle joint, followed for up to 15 years. The authors reported no difference in implant survivorship between patients older or younger than 50 years. Gain in total clinical scores was similar between the groups except a difference in the mobility component score, which was lower in the younger than 50 years patient group. However, the authors used the nonvalidated Kofoed ankle score. Hintermann et al. [7] presented a review on the use of total ankle arthroplasty in elderly patients for the treatment of end-stage arthritis. Authors evaluated the potential advantages of total ankle arthroplasty in patients older than 60 years, comparing to tibiotalar arthrodesis. The authors concluded that TAA should be considered the treatment of choice in elderly patients, especially those with low activity level, as it requires less postoperative immobilization, and allows earlier weightbearing. However the data and methodology leading to this Level 5 conclusion were not presented. The purpose of this study was to compare and functional outcomes, as measured by three-dimensional gait analysis, and patient-reported clinical outcomes, following total ankle arthroplasty between younger patients (50–60 years old) and elderly patients (over 70 years old), in order to determine the effectiveness of this procedure in elderly patients. 2. Methods A prospective gait study of patients with end-stage ankle arthritis, who were treated with the Scandinavian Total
Ankle Replacement (STARTM) total ankle arthroplasty, was conducted. Twenty-one consecutive patients over the age of 70 were identified, and compared with a consecutive group of twenty-one younger patients, aged 50–60 years. All arthroplasties were done by the same senior author (JWB) between the years 1999 to 2011, at the same institution, and by the same surgical team. This study was approved by the Institutional Review Board. Each patient enrolled in the study gave informed consent. Clinical outcome scores collected preoperatively and postoperatively, included the Visual Analog Scale (VAS) pain score, the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle and Hindfoot Score, and the Short Form 36 (SF-36) scores. Minimum followup was 2 years. Subjects underwent a three-dimensional gait analysis before and after total ankle arthroplasty. Minimum follow up for the postoperative gait study was 2 years. Individual subject data was taken from the most recent annual gait analysis. The mean interval between surgery to the latest clinical follow up and gait analysis was 2.3 years for the elderly patients group, and 2.2 years for the group of younger patients. 2.1. Gait analysis Preoperative gait analysis was performed within the 2 weeks prior to the surgery. Kinematic data were collected at 100 Hz with use of a twelve-camera digital Vicon motion capture system (Vicon, Los Angeles, California). Kinetic parameters were collected with two AMTI OR6-5 force plates (Advanced Medical Technology, Watertown, Massachusetts) and recorded at 1000 Hz. Markers position and gait analysis technique were done as previously described using a single segment foot model. Retro-reflective markers were placed bilaterally on the anterior superior iliac spine, the posterior superior iliac spine, laterally on the femur, the lateral epicondyle of the knee, laterally on the tibia, the lateral malleolus, and the head of the second metatarsal and on the posterior aspect of the calcaneus, positioned at the same height as the marker on the second metatarsal head. Markers were also placed bilaterally on the medial epicondyle of the knee and medial malleolus during a standing static trial in order to calculate knee and ankle joint centers, respectively. Patients walked barefoot at a selfselected speed over a 10-m walkway. A minimum of 20 gait cycles were used for averaging and statistical analysis for temporalspatial and kinematics parameters and a minimum of 5 force plate readings were used for kinetic parameters. Gait parameters were collected for both the affected (i.e. operated) limb and the unaffected limb. Temporal-spatial measurements were cadence, step length, walking velocity and single, double and total support times. Kinematic parameters were sagittal plane total range of motion, mean peak plantarflexion and mean peak dorsiflexion for the ankle. Sagittal plane angle at initial contact (IC), minimal and maximal range of motion were measured. Knee and hip total range of motion were recorded as well. Kinetic parameters measured were sagittal plane ankle power and ankle moment. 2.2. Statistical analysis Baseline preoperative measurements were compared between the two age groups using independent sample student t-test for continuous variables. Mixed model was used to evaluate the time, age and time age category interaction effects on gait parameters. Statistical analysis was performed, using JMP 10, by a biostatistician. Statistical significance was set at p < 0.05.
Please cite this article in press as: S. Tenenbaum, et al., Functional and clinical outcomes of total ankle arthroplasty in elderly compared to younger patients, Foot Ankle Surg (2016), http://dx.doi.org/10.1016/j.fas.2016.09.005
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Table 2 Patient-reported clinical outcomes.
3. Results 3.1. Demographic data The elderly patient group was comprised of 13 females and 8 males with a mean age of 74.6 years (range 70–82, SD 3.4). Their mean weight was 78.0 kg (range 50.1–111.1, SD 16.2) and mean height was 167.6 cm (range 154.9–190.5, SD 9.3). The preoperative gait study was performed by a mean of 15.71 days prior to surgery. The average follow up was 2.18 years (range 2.00–3.40) (Table 1). The younger patient study group was comprised of 17 females and 4 males with a mean age of 55.4 years (range 50–59, SD 2.8). The mean weight was 82.6 kg (range 53.6–105.9, SD 16.8) and mean height was 165.4 cm (range 149.8–190.5, SD 12.4). The preop gait analysis was performed by a mean of 17.1 days before surgery. The average follow up in the younger patient group was 2.28 years (range 2.00–3.90). Age was the only significantly different demographic parameter between the two groups (Table 1). To adequately compare groups and determine if the differences observed are statistically significant, a mixed model was used to evaluate the time variable (comparing results of each group before and after surgery to evaluate effect of the intervention); age (group) variable (comparing the changes in each result between young and older patient groups, to evaluate the effect of age on the change) and time-age category interactions (combining the two), each as the main effect on the specific functional parameter of gait. Interaction allows the statistical significance of time and age combined to be calculated as the main effect. Interaction is determined by the slopes of the lines formed from the pre- and post-operative data in both the time and age data. The null hypothesis is set as if both lines are parallel then there is no statistical significance. This method allows a better comparative analysis using both the data from the main effect being time and main effect being intervention [25]. 3.2. Patient reported clinical outcomes Clinical outcome scores improved on VAS, AOFAS Ankle– Hindfoot Score, and SF-36 physical component scores in both patient groups following total ankle arthroplasty (Table 2). Mean VAS pain score decreased from 7.7 to 2.1 in the younger patients group, and from 8.1 to 1.3 in the older patients group. AOFAS ankle/hindfoot score increased from 25.7 to 76.3 in the younger patients group, and from 36.8 to 85.3 in the older patients group. The SF -36 physical component summary scores (PCS) increased from 30.8 to 45.1 in the younger patient group, and from 29.1 to 41.5 in the older patient group. These improvements were statistically significant (Table 2). The multivariate, mixed model analysis of the clinical data showed that the differences in clinical outcome scores, as a result of the intervention with TAA, were statistically significant over time within each group. However, when comparing the changes in
Mean SD
Age group
Clinical measurements
1. Pre
2. Post
Over time
50–60
VAS AOFAS SF36(PCS) SF36(MCS)
7.7 2.4 25.7 14.5 30.8 9.4 51.8 12.2
2.1 2.0 76.3 19.1 45.1 8.6 56.3 6.9
0.0001 0.0001 0.0001 0.2310
Over 70
VAS AOFAS SF36(PCS) SF36(MCS)
8.1 1.9 36.8 17.3 29.1 6.8 55.7 10.1
1.3 1.9 85.3 11.3 41.5 12.7 55.9 5.5
0.0001 0.0001 0.0009 0.9217
P-value
Bold values – statistically significant.
clinical outcome scores between the patient groups in which the primary variables were either age or time + age, there were no statistically significant differences between the groups of elderly and younger patients. Both groups demonstrated benefit from TAA in terms of clinical outcome, regardless of age, and there was no significant difference in the improvements between groups (Table 3). 3.3. Gait analysis This data showed multiple parameters of gait improved following total ankle arthroplasty for both patients group. 3.3.1. Temporal spatial The older patient cohort demonstrated improvement in cadence from 104 to 111 steps/min, walking speed increased from 0.9 to 1.0 m/s, and step length for the affected side increased from 51 to 56 cm. For the unaffected side, step length increased while single support time decreased. In the younger patient cohort there were similar improvements: Cadence increased from 101 to 111 steps/min, walking speed increased from 0.8 to 1.1 m/s, and step length for the affected side increased from 50 to 58 cm. For the unaffected side, step length increased while single support time decreased. Temporal spatial data are summarized in Table 4. 3.3.2. Kinematic data Older patient cohort showed improved kinematic data following surgery. An increase in maximum dorsiflexion (Min) from 6.9 to 8.7, and maximum plantar flexion (Max) from 9.3 to 10.7 were observed. Total range of motion increased from 16.2 to 19.3 , a 19% improvement in range of motion. Similar improvements of kinematic parameters were measured in the younger age group. An increase in maximum dorsiflexion (Min) from 6.5 to 10.6 was observed. Maximum plantar flexion (Max) did not change, and was 6.8 . Total range of motion increased from 13.3 to 17.3 , a 30% improvement in range of motion.
Table 1 Demographic characteristics.
Age @ surgery Height Weight BMI Days before Years post-op
Young group
Geriatric group
p Value
55.40 2.79 (50.20, 59.30) 1,654 124 (1,498, 1,905) 82.69 16.88 (53.60, 105.90) 30.18 5.35 (21.61, 43.81) 15.71 14.78 2.18 0.35 (2.00, 3.40)
74.63 3.40 (70.30, 82.40) 1,676 93 (1,549, 1,9050) 78.03 16.20 (50.10, 111.10) 27.71 5.24 (18.97, 40.76) 17.10 12.32 2.28 0.54 (1.90, 3.90)
0.522 0.367 0.139 0.744 0.459
Mean SD (min, max) by age groups.
Please cite this article in press as: S. Tenenbaum, et al., Functional and clinical outcomes of total ankle arthroplasty in elderly compared to younger patients, Foot Ankle Surg (2016), http://dx.doi.org/10.1016/j.fas.2016.09.005
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Table 3 Multivariate analysis of patient-reported clinical outcome scores. Timing
Age cat: mean SD
P-value Over time
Age group
Time age group
VAS
1. Pre 2. Post
7.7 2.4 2.1 2.0
8.1 1.9 1.3 1.9
0.0001
0.6820
0.2325
AOFAS
1. Pre 2. Post
25.7 14.5 76.3 19.1
36.8 17.3 85.3 11.3
0.0001
0.0094
0.7823
SF36(PCS)
1. Pre 2. Post
30.8 9.4 45.1 8.6
29.1 6.8 41.5 12.7
0.0001
0.2746
0.6763
SF36(MCS)
1. Pre 2. Post
51.8 12.2 56.3 6.9
55.7 10.1 55.9 5.5
0.2704
0.4212
0.3281
50–60
Over 70
Table 4 Temporal spatial data. Timing
Age group: mean SD
P-value
50–60
Over 70
Over time
Age group
Time age group
104.4 10.5 111.8 8.7
0.0001
0.6158
0.4053
Cadence (steps/min)
1. Pre 2. Post
101.4 15.8 111.6 10.7
Walking speed (m/s)
1. Pre 2. Post
0.8 0.3 1.1 0.2
0.9 0.2 1.0 0.2
0.0001
0.6114
0.2738
Step length (cm) affected limb
1. Pre 2. Post
50.2 11.6 58.5 8.1
51.3 10.5 56.1 8.2
0.0026
0.6418
0.4061
Step length unaffected limb (cm)
1. Pre 2. Post
46.8 10.6 56.0 9.1
48.8 10.6 54.9 8.5
0.0004
0.2225
0.4710
Single support affected limb (% gait cycle)
1. Pre 2. Post
39.0 10.1 37.6 5.3
38.7 7.1 37.1 3.9
0.3162
0.6272
0.9587
Single support unaffected limb (% gait cycle)
1. Pre 2. Post
43.6 9.4 40.5 4.7
42.5 7.5 38.4 4.0
0.0169
0.8830
0.7533
Double support affected (% gait cycle)
1. Pre 2. Post
24.6 12.6 23.6 5.9
24.7 7.3 25.2 6.2
0.8957
0.1993
0.6691
Double support unaffected (% gait cycle)
1. Pre 2. Post
24.1 12.5 23.5 6.1
24.0 7.5 24.8 5.7
0.9577
0.2203
0.6810
Total support time affected Limb (% gait cycle)
1. Pre 2. Post
63.7 4.2 61.2 1.6
63.3 2.5 62.3 2.7
0.0050
0.0659
0.2499
Total support time unaffected limb (% gait cycle)
1. Pre 2. Post
67.7 4.8 63.9 2.4
66.5 3.5 63.2 2.7
0.0001
0.0464
0.7285
Bold values – statistically significant.
However, the improvement of sagittal plane angle at initial contact, in the older patient cohort from 3.5 to 2.4 meaning less dorsiflexion, was not observed in the younger group, which changed from 1.4 to 4.0 following surgery (p < 0.0224). Both groups also exhibited similar improvements in hip and knee ROM. In older patient cohort hip range of motion improved from 37.0 to 40.6 , and knee range of motion improved from 52.5 to 54.1. In younger patient cohort hip range of motion improved from 36.8 to 41.9 , and knee range of motion improved from 53.1 to 59.6 . Kinematic data are summarized in Table 5. 3.3.3. Kinetic data Both groups showed similar improvement in ankle moment and ankle power following surgery. In the older patient cohort ankle moment increased from 1.0 to 1.1 Nm/kg, and ankle power increased from 0.8 to 1.1 W/kg. In the younger patient cohort ankle moment increased from 1.0 to 1.1 Nm/kg, and ankle power
increased from 0.7 to 1.2 W/kg. Kinetic data are summarized in Table 5. 4. Discussion This work continues to elucidate the benefits, advantages, and disadvantages of total ankle arthroplasty in elderly patients, for the treatment of end-stage ankle arthritis. It has been postulated of the preservation of motion in total ankle arthroplasty may reduce the incidence or severity of arthritis in the adjacent joints of the hindfoot and midfoot [35–39]. However, many elderly patients have a reduced level of physical activity and it is unproven whether they will develop secondary arthritis in the surrounding joints within their lifetime, potentially making less cogent this argument for arthroplasty in this age cohort. This further implores the foot and ankle specialist to determine clear benefits for utilization of TAA in this patient population. It has been hypothesized that other benefits of total
Please cite this article in press as: S. Tenenbaum, et al., Functional and clinical outcomes of total ankle arthroplasty in elderly compared to younger patients, Foot Ankle Surg (2016), http://dx.doi.org/10.1016/j.fas.2016.09.005
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Table 5 Kinetic and kinematic data. Timing
Age group: mean SD
P-value Over time
Age group
Time age group
Sagittal plane angle at initial contact (deg)
1. Pre 2. Post
1.4 4.5 4.0 3.6
3.5 3.9 2.4 2.2
0.3180
0.7617
0.0224
Sagittal plane angle at minimum ROM (deg)
1. Pre 2. Post
6.5 6.1 10.6 6.7
6.9 4.0 8.7 3.9
0.0038
0.5815
0.2387
Sagittal plane angle at maximum ROM (deg)
1. Pre 2. Post
6.8 4.4 6.8 4.7
9.3 5.2 10.7 3.3
0.4118
0.0062
0.4213
Total sagittal ROM (deg)
1. Pre 2. Post
13.3 4.6 17.3 5.9
16.2 4.5 19.3 4.3
0.0001
0.0651
0.5734
Max dorsiflexion at midstance (deg)
1. Pre 2. Post
6.8 4.4 6.8 4.7
9.3 5.2 10.7 3.3
0.4100
0.0061
0.4227
Max plantarflexion at toe-off (deg)
1. Pre 2. Post
5.7 6.3 10.2 7.1
5.3 4.8 8.0 4.9
0.0023
0.3851
0.4019
Knee ROM (deg)
1. Pre 2. Post
53.1 11.0 59.6 10.2
52.5 6.0 54.1 7.3
0.0409
0.8838
0.2044
Hip ROM (deg)
1. Pre 2. Post
36.8 9.7 41.9 6.1
37.0 8.0 40.6 4.7
0.0074
0.9181
0.6307
Ankle moment (Nm/kg)
1. Pre 2. Post
1.0 0.3 1.1 0.3
1.0 0.3 1.1 0.2
0.0465
0.3522
0.8894
Ankle power (W/kg)
1. Pre 2. Post
0.7 0.5 1.2 0.5
0.8 0.4 1.1 0.4
0.0001
0.7781
0.3228
50–60
Over 70
Bold values – statistically significant.
ankle arthroplasty are shorter postoperative immobilization with earlier weight-bearing, leading to less physical deconditioning in the postoperative period, and better restoration of hindfoot biomechanics leading to less gait adaptations [7]. One question that has not been previously investigated is whether TAA can be measured to be equally effective in older patients. Previous studies of gait analysis following TAA have demonstrated significant improvement in gait parameters, even though gait is not restored to normal [5,12,13,17–23]. Kofoed and Lundberg-Jensen [9] compared 30 patients who were younger than 50 years, to 70 patients older than 50 years, treated with total ankle arthroplasty. Authors showed that implant survival, defined as revision of prosthesis or conversion to arthrodesis, did not differ between the groups. The clinical scores were not comparable between the groups, attributable to the mobility sub-score. The authors concluded that the two age groups had equivalent results. Interpretation and comparison of that study to current work is limited by that particular scoring system which is not widely utilized, and not validated. A study by Demetracopoulos et al. [34] examined the effect of age on total ankle arthroplasty outcome. Three groups of patients based on age (<55, 55–70, and >70 years) were compared. Authors showed that patients under the age of 55 had a greater improvement in SF-36 vitality subscale, and AOFAS function subscore, compared with patients over the age of 70. No differences in the VAS pain score or the physical performance outcome was found between the age groups. Of note, patient physical performance was assessed by clinical measurement of range of motion, and functional tests (Timed Up and Go (TUG) test, Sit-to-Stand (STS) test and Square Step Test (4SST)) but not with, formal gait analysis. Also, three different ankle prostheses were used, introducing potential variation bias to the results. To our best of knowledge, the current study is the first to directly compare the results of TAA in elderly patients (age > 70) to middle-
aged patients (age 50–60) using both clinical patient-reported outcome scores as well as objective functional measurements with gait analysis to measure physical performance. The nature and magnitude of the improvements in clinical outcome scores in this study are compatible with previous reports [34,40–42]. In this study, temporal-spatial, kinematic and kinematic parameters improved following TAA in both groups in character and amount comparable to multiple previous reports in the literature on the affect of ankle arthroplasty on gait metrics [3,10,17,22,26,43]. This was important to confirm that the objective results were within expected range, prior to making the comparative analysis according to age groups separated by almost 20 years. In this study, the older patient group had an increase in both plantar flexion and dorsiflexion, while for the younger patient group only dorsiflexion increased. We are uncertain to what this difference between the groups should be attributed. Choi et al. [26] reported on 21 patients treated with a fixed bearing prosthesis in which most of the increase in motion occurred in the range of dorsiflexion, while Brodsky et al. [22] who studied 50 patients after STAR ankle arthroplasty, and Hahn et al. [17] who studied 9 patients after a fixed-bearing ankle arthroplasty, found that most of the increase occurred in plantarflexion. Whether these differences are related to variations in prosthetic design, surgical instrumentation, or the vagaries of surgical technique is unknown. Several weaknesses of study should be recognized. First, these groups were sequential, and not randomly selected. This, by definition may result in inherent selection bias. Also some unrevealed bias is possible, such as younger patients with endstage ankle arthritis may have a history of greater activity level, or more recent ligament injury. Second, this work provides no comparison to other surgical alternatives such as ankle
Please cite this article in press as: S. Tenenbaum, et al., Functional and clinical outcomes of total ankle arthroplasty in elderly compared to younger patients, Foot Ankle Surg (2016), http://dx.doi.org/10.1016/j.fas.2016.09.005
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arthrodesis. Third, no data was collected on the speed of recovery or adverse events, although no patients were excluded for implant failure, removal or revision of the arthroplasty. Last, the AOFAS Ankle–Hindfoot Score is a legacy score, whose use dates to the beginning of this series in 1999, and precedes the current era that emphasizes validated scores, like the VAS pain scale, and the SF-36, but it was included for consistency, and for comparison to the many prior published studies which have reported results using it. Both patient age groups had improvements in clinical outcome scores and in functional metrics of ambulation following total ankle arthroplasty. Total ankle arthroplasty is valuable tool for treatment of end stage ankle arthritis when utilized in the appropriate setting, and this work reinforces the role of ankle arthroplasty when treating the elderly patient with end stage ankle arthritis. In this comparative study, it is shown that both elderly patients over the age of 70 and younger patients aged 50–60 demonstrated equivalent improvements in clinical and gait outcomes following ankle arthroplasty, which may be important data both for clinical decision-making and for the health economics for our ageing population. Conflict of interest The Authors declare they have no conflict of interest pertaining with this manuscript, including, but not limited to employment, consultancies, stock ownership, honoraria, paid expert testimony, patent applications/registrations, and grants or other funding. References [1] Bonnin M, et al. Midterm results of the Salto Total Ankle Prosthesis. Clin Orthop Relat Res 2016;2004(424):6–18. [2] Bonnin MP, Laurent JR, Casillas M. Ankle function and sports activity after total ankle arthroplasty. Foot Ankle Int 2009;30(10):933–44. [3] Dyrby C, et al. Functional evaluation of the Scandinavian Total Ankle Replacement. Foot Ankle Int 2004;25(6):377–81. [4] Gougoulias N, Khanna A, Maffulli N. How successful are current ankle replacements?: a systematic review of the literature. Clin Orthop Relat Res 2010;468(1):199–208. [5] Haddad SL, et al. Intermediate and long-term outcomes of total ankle arthroplasty and ankle arthrodesis. A systematic review of the literature. J Bone Joint Surg Am 2007;89(9):1899–905. [6] Helm R, Stevens J. Long-term results of total ankle replacement. J Arthroplasty 1986;1(4):271–7. [7] Hintermann B, et al. Total ankle replacement for treatment of end-stage osteoarthritis in elderly patients. J Aging Res 2012;2012:345237. [8] Knecht SI, et al. The Agility total ankle arthroplasty. Seven to sixteen-year follow-up. J Bone Joint Surg Am 2004;86-A(6):1161–71. [9] Kofoed H, Lundberg-Jensen A. Ankle arthroplasty in patients younger and older than 50 years: a prospective series with long-term follow-up. Foot Ankle Int 1999;20(8):501–6. [10] Queen RM, et al. J. Leonard Goldner Award 2011: changes in pain, function, and gait mechanics two years following total ankle arthroplasty performed with two modern fixed-bearing prostheses. Foot Ankle Int 2012;33(7):535–42. [11] Rouhani H, et al. Multi-segment foot kinematics after total ankle replacement and ankle arthrodesis during relatively long-distance gait. Gait Posture 2012;36(3):561–6. [12] Saltzman CL, Kadoko RG, Suh JS. Treatment of isolated ankle osteoarthritis with arthrodesis or the total ankle replacement: a comparison of early outcomes. Clin Orthop Surg 2010;2(1):1–7.
[13] Saltzman CL, et al. Prospective controlled trial of STAR total ankle replacement versus ankle fusion: initial results. Foot Ankle Int 2009;30(7):579–96. [14] Schuh R, et al. Total ankle arthroplasty versus ankle arthrodesis. Comparison of sports, recreational activities and functional outcome. Int Orthop 2012;36 (6):1207–14. [15] Stauffer RN, Segal NM. Total ankle arthroplasty: four years’ experience. Clin Orthop Relat Res 1981;(160):217–21. [16] Wood PL, Deakin S. Total ankle replacement. The results in 200 ankles. J Bone Joint Surg Br 2003;85(3):334–41. [17] Hahn ME, et al. Comparative gait analysis of ankle arthrodesis and arthroplasty: initial findings of a prospective study. Foot Ankle Int 2012;33 (4):282–9. [18] Piriou P, et al. Ankle replacement versus arthrodesis: a comparative gait analysis study. Foot Ankle Int 2008;29(1):3–9. [19] Valderrabano V, et al. Kinematic changes after fusion and total replacement of the ankle: part 3: talar movement. Foot Ankle Int 2003;24(12):897–900. [20] Valderrabano V, et al. Kinematic changes after fusion and total replacement of the ankle: part 2: movement transfer. Foot Ankle Int 2003;24(12):888–96. [21] Valderrabano V, et al. Kinematic changes after fusion and total replacement of the ankle: part 1: range of motion. Foot Ankle Int 2003;24(12):881–7. [22] Brodsky JW, et al. Changes in gait following the Scandinavian Total Ankle Replacement. J Bone Joint Surg Am 2011;93(20):1890–6. [23] Brodsky JW, et al. Hindfoot motion following STAR total ankle arthroplasty: a multisegment foot model gait study. Foot Ankle Int 2013;34(11):1479–85. [24] Zaidi R, et al. The outcome of total ankle replacement: a systematic review and meta-analysis. Bone Joint J 2013;95-B(11):1500–7. [25] Flavin R, et al. Comparison of gait after total ankle arthroplasty and ankle arthrodesis. Foot Ankle Int 2013;34(10):1340–8. [26] Choi JH, et al. Prospective study of the effect on gait of a two-component total ankle replacement. Foot Ankle Int 2013;34(11):1472–8. [27] Queen RM, et al. Bilateral differences in gait mechanics following total ankle replacement: a two year longitudinal study. Clin Biomech (Bristol, Avon) 2014;29(4):418–22. [28] Chopra S, et al. Outcome of unilateral ankle arthrodesis and total ankle replacement in terms of bilateral gait mechanics. J Orthop Res 2014;32 (3):377–84. [29] Vincent GK, Velkoff VA, U.S. Census Bureau. The next four decades: the older population in the United States: 2010 to 2050. Population estimates and projections. Washington, D.C: U.S. Dept. of Commerce, Economics and Statistics Administration, U.S. Census Bureau; 2010 14 pp. [30] Strasser NL, Turner NS. Functional outcomes after ankle arthrodesis in elderly patients. Foot Ankle Int 2012;33(9):699–703. [31] Spirt AA, Assal M, Hansen Jr. ST. Complications and failure after total ankle arthroplasty. J Bone Joint Surg Am 2004;86-A(6):1172–8. [32] Henricson A, Skoog A, Carlsson A. The Swedish Ankle Arthroplasty Register: an analysis of 531 arthroplasties between 1993 and 2005. Acta Orthop 2007;78 (5):569–74. [33] Fevang BT, et al. 257 ankle arthroplasties performed in Norway between 1994 and 2005. Acta Orthop 2007;78(5):575–83. [34] Demetracopoulos CA, et al. Effect of age on outcomes in total ankle arthroplasty. Foot Ankle Int 2015;36(8):871–80. [35] Buck P, Morrey BF, Chao EY. The optimum position of arthrodesis of the ankle: a gait study of the knee and ankle. J Bone Joint Surg Am 1987;69(7):1052–62. [36] Coester LM, et al. Long-term results following ankle arthrodesis for posttraumatic arthritis. J Bone Joint Surg Am 2001;83-A(2):219–28. [37] Jackson A, Glasgow M. Tarsal hypermobility after ankle fusion—fact or fiction? J Bone Joint Surg Br 1979;61-B(4):470–3. [38] Mazur JM, Schwartz E, Simon SR. Ankle arthrodesis. Long-term follow-up with gait analysis. J Bone Joint Surg Am 1979;61(7):964–75. [39] Said E, Hunka L, Siller TN. Where ankle fusion stands today. J Bone Joint Surg Br 1978;60-B(2):211–4. [40] Schweitzer KM, et al. Early prospective clinical results of a modern fixedbearing total ankle arthroplasty. J Bone Joint Surg Am 2013;95(11):1002–11. [41] Schenk K, et al. Prospective study of a cementless, mobile-bearing, third generation total ankle prosthesis. Foot Ankle Int 2011;32(8):755–63. [42] Reuver JM, et al. Total ankle replacement outcome in low volume centers: short-term followup. Foot Ankle Int 2010;31(12):1064–8. [43] Valderrabano V, et al. Gait analysis in ankle osteoarthritis and total ankle replacement. Clin Biomech (Bristol, Avon) 2007;22(8):894–904.
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Foot and Ankle Surgery xxx (2016) xxx–xxx
Contents lists available at ScienceDirect
Foot and Ankle Surgery journal homepage: www.elsevier.com/locate/fas
Functional and clinical outcomes of total ankle arthroplasty in elderly compared to younger patients$,$$ Shay Tenenbaum, MDa,* , Jason Bariteau, MDb , Scott Coleman, MS, MBAc , James Brodsky, MDc a b c
Department of Orthopedic Surgery, Chaim Sheba Medical Center at Tel HaShomer, Affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Israel Department of Orthopedic Surgery, Emory University School of Medicine, Atlanta, GA, USA Department of Orthopedic Surgery, Baylor University Medical Center, Dallas, TX, USA
A R T I C L E I N F O
A B S T R A C T
Article history: Received 16 August 2016 Received in revised form 27 September 2016 Accepted 30 September 2016 Available online xxx
Background: Total ankle arthroplasty (TAA) is becoming an increasingly utilized procedure for the management of end-stage ankle arthritis. Elderly patients are the fastest growing segment of the population in the western world, creating a unique challenge to the health economics of our era. Determining if elderly patients with end-stage ankle arthritis demonstrate the same improvements in clinical outcomes and functional measures of gait following TAA would be valuable. This can aid to evaluate the utilization of TAA in this enlarging cohort of our population. Methods: Consecutive series of twenty-one patients over the age of 70, who underwent TAA for end-stage ankle arthritis, was prospectively compared to a series of twenty-one patients aged 50–60, who underwent the same procedure by single surgeon during same time period. Clinical outcomes were measured with outcome scores including VAS pain score, AOFAS Ankle and Hindfoot Score, and the SF-36. Three-dimensional gait analysis was performed preoperatively and at a minimum of one year postoperatively, to measure temporal-spatial, kinematic, and kinetic parameters of gait. Mixed model multivariate statistical analysis was used to evaluate and compare the independent contributions to outcomes of the surgical intervention over time; of patient age; and of time-plus-age interaction, as these influenced both the clinical outcomes and the functional gait outcomes. Results: Statistically significant improvements in VAS pain scores, AOFAS ankle/hindfoot scores, and SF36 scores were demonstrated in both age groups. Following surgery, there were improvements in all parameters of gait, including temporal-spatial parameters as step length and walking velocity; kinematic parameters, including, increase in total range of motion to a total of 17–19 ; and kinetic parameters, including increase in ankle power and moment. The improvements both in clinical and gait outcomes were equivalent in the two age groups. Conclusions: In this comparative study, it is shown that both elderly patients over the age of 70 and younger patients aged 50–60 demonstrated equivalent improvements clinical and gait outcomes following ankle arthroplasty. This may be important data both for clinical decision-making and the health economics for our ageing population. ã 2016 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
Keywords: Geriatric Total ankle replacement Gait study
1. Introduction Total ankle arthroplasty is gaining popularity as treatment for end-stage ankle arthritis. Multiple authors, using a range of
$ An investigation of the Human Motion and Performance Laboratory of Baylor University Medical Center, Dallas, Texas. $$ Level of evidence: Level 3, retrospective cohort. * Corresponding author. E-mail address: [email protected] (S. Tenenbaum).
different prostheses, have reported encouraging clinical results following total ankle arthroplasty with improved function and significant pain reduction [1–16]. In addition to positive clinical outcomes, multiple studies have documented functional improvement, as measured by improvements in gait following total ankle arthroplasty. Recent gait studies have shown that ankle arthroplasty significantly produces improved gait compared with preoperative gait, even though does not restore gait to the level normal controls [5,12,13,17–24].
http://dx.doi.org/10.1016/j.fas.2016.09.005 1268-7731/ã 2016 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: S. Tenenbaum, et al., Functional and clinical outcomes of total ankle arthroplasty in elderly compared to younger patients, Foot Ankle Surg (2016), http://dx.doi.org/10.1016/j.fas.2016.09.005
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Ankle arthroplasty has been shown to produce increased joint movement, improved symmetry of gait, and restoration of a more normal pattern of ground reaction force [17,22,23,25–28]. Elderly patients are the fastest growing segment of the population in the western world, creating a unique challenge to the health economics of our era [29]. Determining if elderly patients with end-stage ankle arthritis demonstrate the same improvements in clinical outcomes and in functional measures of gait following TAA would be valuable to determine the appropriate utilization of this procedure in this enlarging cohort of our population. Strasser and Turner [30] retrospectively studied ankle arthrodesis outcomes in elderly patients over the age of 70. Authors showed, functional outcomes measured with FAAM and AOFAS scores to be satisfactory, and union rate to be comparable with previous reports for younger patients. Authors concluded that ankle arthrodesis is an effective surgical treatment option in an elderly patient population. However, it is yet undetermined whether elderly patients with end-stage ankle arthritis experience the same clinical and functional improvements produced by ankle arthroplasty as younger patients. Only a handful of studies addressed the performance of patients undergoing total ankle arthroplasty according to patients’ age. These studies focused mainly, on complications, implant survival and revision rates [31–33]. Fevang et al. [33] showed age did not influence revision rates. Conversely, Henricson et al. [32] showed that a lower age at time of index surgery implied increased risk for revision. Spirt et al. [31] reported that patients under the age of 54 who underwent TAA had a 1.45-times greater risk of reoperation and a 2.65-times greater risk of implant failure than older patients. A recent study [34] examined the effect of age on total ankle arthroplasty on patient-reported outcomes. Authors showed that younger patients had similar clinical outcomes as older patients in early followup. However, no functional measurements such as gait analysis were utilized. Kofoed and Lundberg-Jensen [9] retrospectively, reported on 100 patients treated with total ankle arthroplasty for osteoarthritis or rheumatoid arthritis of the ankle joint, followed for up to 15 years. The authors reported no difference in implant survivorship between patients older or younger than 50 years. Gain in total clinical scores was similar between the groups except a difference in the mobility component score, which was lower in the younger than 50 years patient group. However, the authors used the nonvalidated Kofoed ankle score. Hintermann et al. [7] presented a review on the use of total ankle arthroplasty in elderly patients for the treatment of end-stage arthritis. Authors evaluated the potential advantages of total ankle arthroplasty in patients older than 60 years, comparing to tibiotalar arthrodesis. The authors concluded that TAA should be considered the treatment of choice in elderly patients, especially those with low activity level, as it requires less postoperative immobilization, and allows earlier weightbearing. However the data and methodology leading to this Level 5 conclusion were not presented. The purpose of this study was to compare and functional outcomes, as measured by three-dimensional gait analysis, and patient-reported clinical outcomes, following total ankle arthroplasty between younger patients (50–60 years old) and elderly patients (over 70 years old), in order to determine the effectiveness of this procedure in elderly patients. 2. Methods A prospective gait study of patients with end-stage ankle arthritis, who were treated with the Scandinavian Total
Ankle Replacement (STARTM) total ankle arthroplasty, was conducted. Twenty-one consecutive patients over the age of 70 were identified, and compared with a consecutive group of twenty-one younger patients, aged 50–60 years. All arthroplasties were done by the same senior author (JWB) between the years 1999 to 2011, at the same institution, and by the same surgical team. This study was approved by the Institutional Review Board. Each patient enrolled in the study gave informed consent. Clinical outcome scores collected preoperatively and postoperatively, included the Visual Analog Scale (VAS) pain score, the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle and Hindfoot Score, and the Short Form 36 (SF-36) scores. Minimum followup was 2 years. Subjects underwent a three-dimensional gait analysis before and after total ankle arthroplasty. Minimum follow up for the postoperative gait study was 2 years. Individual subject data was taken from the most recent annual gait analysis. The mean interval between surgery to the latest clinical follow up and gait analysis was 2.3 years for the elderly patients group, and 2.2 years for the group of younger patients. 2.1. Gait analysis Preoperative gait analysis was performed within the 2 weeks prior to the surgery. Kinematic data were collected at 100 Hz with use of a twelve-camera digital Vicon motion capture system (Vicon, Los Angeles, California). Kinetic parameters were collected with two AMTI OR6-5 force plates (Advanced Medical Technology, Watertown, Massachusetts) and recorded at 1000 Hz. Markers position and gait analysis technique were done as previously described using a single segment foot model. Retro-reflective markers were placed bilaterally on the anterior superior iliac spine, the posterior superior iliac spine, laterally on the femur, the lateral epicondyle of the knee, laterally on the tibia, the lateral malleolus, and the head of the second metatarsal and on the posterior aspect of the calcaneus, positioned at the same height as the marker on the second metatarsal head. Markers were also placed bilaterally on the medial epicondyle of the knee and medial malleolus during a standing static trial in order to calculate knee and ankle joint centers, respectively. Patients walked barefoot at a selfselected speed over a 10-m walkway. A minimum of 20 gait cycles were used for averaging and statistical analysis for temporalspatial and kinematics parameters and a minimum of 5 force plate readings were used for kinetic parameters. Gait parameters were collected for both the affected (i.e. operated) limb and the unaffected limb. Temporal-spatial measurements were cadence, step length, walking velocity and single, double and total support times. Kinematic parameters were sagittal plane total range of motion, mean peak plantarflexion and mean peak dorsiflexion for the ankle. Sagittal plane angle at initial contact (IC), minimal and maximal range of motion were measured. Knee and hip total range of motion were recorded as well. Kinetic parameters measured were sagittal plane ankle power and ankle moment. 2.2. Statistical analysis Baseline preoperative measurements were compared between the two age groups using independent sample student t-test for continuous variables. Mixed model was used to evaluate the time, age and time age category interaction effects on gait parameters. Statistical analysis was performed, using JMP 10, by a biostatistician. Statistical significance was set at p < 0.05.
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Table 2 Patient-reported clinical outcomes.
3. Results 3.1. Demographic data The elderly patient group was comprised of 13 females and 8 males with a mean age of 74.6 years (range 70–82, SD 3.4). Their mean weight was 78.0 kg (range 50.1–111.1, SD 16.2) and mean height was 167.6 cm (range 154.9–190.5, SD 9.3). The preoperative gait study was performed by a mean of 15.71 days prior to surgery. The average follow up was 2.18 years (range 2.00–3.40) (Table 1). The younger patient study group was comprised of 17 females and 4 males with a mean age of 55.4 years (range 50–59, SD 2.8). The mean weight was 82.6 kg (range 53.6–105.9, SD 16.8) and mean height was 165.4 cm (range 149.8–190.5, SD 12.4). The preop gait analysis was performed by a mean of 17.1 days before surgery. The average follow up in the younger patient group was 2.28 years (range 2.00–3.90). Age was the only significantly different demographic parameter between the two groups (Table 1). To adequately compare groups and determine if the differences observed are statistically significant, a mixed model was used to evaluate the time variable (comparing results of each group before and after surgery to evaluate effect of the intervention); age (group) variable (comparing the changes in each result between young and older patient groups, to evaluate the effect of age on the change) and time-age category interactions (combining the two), each as the main effect on the specific functional parameter of gait. Interaction allows the statistical significance of time and age combined to be calculated as the main effect. Interaction is determined by the slopes of the lines formed from the pre- and post-operative data in both the time and age data. The null hypothesis is set as if both lines are parallel then there is no statistical significance. This method allows a better comparative analysis using both the data from the main effect being time and main effect being intervention [25]. 3.2. Patient reported clinical outcomes Clinical outcome scores improved on VAS, AOFAS Ankle– Hindfoot Score, and SF-36 physical component scores in both patient groups following total ankle arthroplasty (Table 2). Mean VAS pain score decreased from 7.7 to 2.1 in the younger patients group, and from 8.1 to 1.3 in the older patients group. AOFAS ankle/hindfoot score increased from 25.7 to 76.3 in the younger patients group, and from 36.8 to 85.3 in the older patients group. The SF -36 physical component summary scores (PCS) increased from 30.8 to 45.1 in the younger patient group, and from 29.1 to 41.5 in the older patient group. These improvements were statistically significant (Table 2). The multivariate, mixed model analysis of the clinical data showed that the differences in clinical outcome scores, as a result of the intervention with TAA, were statistically significant over time within each group. However, when comparing the changes in
Mean SD
Age group
Clinical measurements
1. Pre
2. Post
Over time
50–60
VAS AOFAS SF36(PCS) SF36(MCS)
7.7 2.4 25.7 14.5 30.8 9.4 51.8 12.2
2.1 2.0 76.3 19.1 45.1 8.6 56.3 6.9
0.0001 0.0001 0.0001 0.2310
Over 70
VAS AOFAS SF36(PCS) SF36(MCS)
8.1 1.9 36.8 17.3 29.1 6.8 55.7 10.1
1.3 1.9 85.3 11.3 41.5 12.7 55.9 5.5
0.0001 0.0001 0.0009 0.9217
P-value
Bold values – statistically significant.
clinical outcome scores between the patient groups in which the primary variables were either age or time + age, there were no statistically significant differences between the groups of elderly and younger patients. Both groups demonstrated benefit from TAA in terms of clinical outcome, regardless of age, and there was no significant difference in the improvements between groups (Table 3). 3.3. Gait analysis This data showed multiple parameters of gait improved following total ankle arthroplasty for both patients group. 3.3.1. Temporal spatial The older patient cohort demonstrated improvement in cadence from 104 to 111 steps/min, walking speed increased from 0.9 to 1.0 m/s, and step length for the affected side increased from 51 to 56 cm. For the unaffected side, step length increased while single support time decreased. In the younger patient cohort there were similar improvements: Cadence increased from 101 to 111 steps/min, walking speed increased from 0.8 to 1.1 m/s, and step length for the affected side increased from 50 to 58 cm. For the unaffected side, step length increased while single support time decreased. Temporal spatial data are summarized in Table 4. 3.3.2. Kinematic data Older patient cohort showed improved kinematic data following surgery. An increase in maximum dorsiflexion (Min) from 6.9 to 8.7, and maximum plantar flexion (Max) from 9.3 to 10.7 were observed. Total range of motion increased from 16.2 to 19.3 , a 19% improvement in range of motion. Similar improvements of kinematic parameters were measured in the younger age group. An increase in maximum dorsiflexion (Min) from 6.5 to 10.6 was observed. Maximum plantar flexion (Max) did not change, and was 6.8 . Total range of motion increased from 13.3 to 17.3 , a 30% improvement in range of motion.
Table 1 Demographic characteristics.
Age @ surgery Height Weight BMI Days before Years post-op
Young group
Geriatric group
p Value
55.40 2.79 (50.20, 59.30) 1,654 124 (1,498, 1,905) 82.69 16.88 (53.60, 105.90) 30.18 5.35 (21.61, 43.81) 15.71 14.78 2.18 0.35 (2.00, 3.40)
74.63 3.40 (70.30, 82.40) 1,676 93 (1,549, 1,9050) 78.03 16.20 (50.10, 111.10) 27.71 5.24 (18.97, 40.76) 17.10 12.32 2.28 0.54 (1.90, 3.90)
0.522 0.367 0.139 0.744 0.459
Mean SD (min, max) by age groups.
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Table 3 Multivariate analysis of patient-reported clinical outcome scores. Timing
Age cat: mean SD
P-value Over time
Age group
Time age group
VAS
1. Pre 2. Post
7.7 2.4 2.1 2.0
8.1 1.9 1.3 1.9
0.0001
0.6820
0.2325
AOFAS
1. Pre 2. Post
25.7 14.5 76.3 19.1
36.8 17.3 85.3 11.3
0.0001
0.0094
0.7823
SF36(PCS)
1. Pre 2. Post
30.8 9.4 45.1 8.6
29.1 6.8 41.5 12.7
0.0001
0.2746
0.6763
SF36(MCS)
1. Pre 2. Post
51.8 12.2 56.3 6.9
55.7 10.1 55.9 5.5
0.2704
0.4212
0.3281
50–60
Over 70
Table 4 Temporal spatial data. Timing
Age group: mean SD
P-value
50–60
Over 70
Over time
Age group
Time age group
104.4 10.5 111.8 8.7
0.0001
0.6158
0.4053
Cadence (steps/min)
1. Pre 2. Post
101.4 15.8 111.6 10.7
Walking speed (m/s)
1. Pre 2. Post
0.8 0.3 1.1 0.2
0.9 0.2 1.0 0.2
0.0001
0.6114
0.2738
Step length (cm) affected limb
1. Pre 2. Post
50.2 11.6 58.5 8.1
51.3 10.5 56.1 8.2
0.0026
0.6418
0.4061
Step length unaffected limb (cm)
1. Pre 2. Post
46.8 10.6 56.0 9.1
48.8 10.6 54.9 8.5
0.0004
0.2225
0.4710
Single support affected limb (% gait cycle)
1. Pre 2. Post
39.0 10.1 37.6 5.3
38.7 7.1 37.1 3.9
0.3162
0.6272
0.9587
Single support unaffected limb (% gait cycle)
1. Pre 2. Post
43.6 9.4 40.5 4.7
42.5 7.5 38.4 4.0
0.0169
0.8830
0.7533
Double support affected (% gait cycle)
1. Pre 2. Post
24.6 12.6 23.6 5.9
24.7 7.3 25.2 6.2
0.8957
0.1993
0.6691
Double support unaffected (% gait cycle)
1. Pre 2. Post
24.1 12.5 23.5 6.1
24.0 7.5 24.8 5.7
0.9577
0.2203
0.6810
Total support time affected Limb (% gait cycle)
1. Pre 2. Post
63.7 4.2 61.2 1.6
63.3 2.5 62.3 2.7
0.0050
0.0659
0.2499
Total support time unaffected limb (% gait cycle)
1. Pre 2. Post
67.7 4.8 63.9 2.4
66.5 3.5 63.2 2.7
0.0001
0.0464
0.7285
Bold values – statistically significant.
However, the improvement of sagittal plane angle at initial contact, in the older patient cohort from 3.5 to 2.4 meaning less dorsiflexion, was not observed in the younger group, which changed from 1.4 to 4.0 following surgery (p < 0.0224). Both groups also exhibited similar improvements in hip and knee ROM. In older patient cohort hip range of motion improved from 37.0 to 40.6 , and knee range of motion improved from 52.5 to 54.1. In younger patient cohort hip range of motion improved from 36.8 to 41.9 , and knee range of motion improved from 53.1 to 59.6 . Kinematic data are summarized in Table 5. 3.3.3. Kinetic data Both groups showed similar improvement in ankle moment and ankle power following surgery. In the older patient cohort ankle moment increased from 1.0 to 1.1 Nm/kg, and ankle power increased from 0.8 to 1.1 W/kg. In the younger patient cohort ankle moment increased from 1.0 to 1.1 Nm/kg, and ankle power
increased from 0.7 to 1.2 W/kg. Kinetic data are summarized in Table 5. 4. Discussion This work continues to elucidate the benefits, advantages, and disadvantages of total ankle arthroplasty in elderly patients, for the treatment of end-stage ankle arthritis. It has been postulated of the preservation of motion in total ankle arthroplasty may reduce the incidence or severity of arthritis in the adjacent joints of the hindfoot and midfoot [35–39]. However, many elderly patients have a reduced level of physical activity and it is unproven whether they will develop secondary arthritis in the surrounding joints within their lifetime, potentially making less cogent this argument for arthroplasty in this age cohort. This further implores the foot and ankle specialist to determine clear benefits for utilization of TAA in this patient population. It has been hypothesized that other benefits of total
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Table 5 Kinetic and kinematic data. Timing
Age group: mean SD
P-value Over time
Age group
Time age group
Sagittal plane angle at initial contact (deg)
1. Pre 2. Post
1.4 4.5 4.0 3.6
3.5 3.9 2.4 2.2
0.3180
0.7617
0.0224
Sagittal plane angle at minimum ROM (deg)
1. Pre 2. Post
6.5 6.1 10.6 6.7
6.9 4.0 8.7 3.9
0.0038
0.5815
0.2387
Sagittal plane angle at maximum ROM (deg)
1. Pre 2. Post
6.8 4.4 6.8 4.7
9.3 5.2 10.7 3.3
0.4118
0.0062
0.4213
Total sagittal ROM (deg)
1. Pre 2. Post
13.3 4.6 17.3 5.9
16.2 4.5 19.3 4.3
0.0001
0.0651
0.5734
Max dorsiflexion at midstance (deg)
1. Pre 2. Post
6.8 4.4 6.8 4.7
9.3 5.2 10.7 3.3
0.4100
0.0061
0.4227
Max plantarflexion at toe-off (deg)
1. Pre 2. Post
5.7 6.3 10.2 7.1
5.3 4.8 8.0 4.9
0.0023
0.3851
0.4019
Knee ROM (deg)
1. Pre 2. Post
53.1 11.0 59.6 10.2
52.5 6.0 54.1 7.3
0.0409
0.8838
0.2044
Hip ROM (deg)
1. Pre 2. Post
36.8 9.7 41.9 6.1
37.0 8.0 40.6 4.7
0.0074
0.9181
0.6307
Ankle moment (Nm/kg)
1. Pre 2. Post
1.0 0.3 1.1 0.3
1.0 0.3 1.1 0.2
0.0465
0.3522
0.8894
Ankle power (W/kg)
1. Pre 2. Post
0.7 0.5 1.2 0.5
0.8 0.4 1.1 0.4
0.0001
0.7781
0.3228
50–60
Over 70
Bold values – statistically significant.
ankle arthroplasty are shorter postoperative immobilization with earlier weight-bearing, leading to less physical deconditioning in the postoperative period, and better restoration of hindfoot biomechanics leading to less gait adaptations [7]. One question that has not been previously investigated is whether TAA can be measured to be equally effective in older patients. Previous studies of gait analysis following TAA have demonstrated significant improvement in gait parameters, even though gait is not restored to normal [5,12,13,17–23]. Kofoed and Lundberg-Jensen [9] compared 30 patients who were younger than 50 years, to 70 patients older than 50 years, treated with total ankle arthroplasty. Authors showed that implant survival, defined as revision of prosthesis or conversion to arthrodesis, did not differ between the groups. The clinical scores were not comparable between the groups, attributable to the mobility sub-score. The authors concluded that the two age groups had equivalent results. Interpretation and comparison of that study to current work is limited by that particular scoring system which is not widely utilized, and not validated. A study by Demetracopoulos et al. [34] examined the effect of age on total ankle arthroplasty outcome. Three groups of patients based on age (<55, 55–70, and >70 years) were compared. Authors showed that patients under the age of 55 had a greater improvement in SF-36 vitality subscale, and AOFAS function subscore, compared with patients over the age of 70. No differences in the VAS pain score or the physical performance outcome was found between the age groups. Of note, patient physical performance was assessed by clinical measurement of range of motion, and functional tests (Timed Up and Go (TUG) test, Sit-to-Stand (STS) test and Square Step Test (4SST)) but not with, formal gait analysis. Also, three different ankle prostheses were used, introducing potential variation bias to the results. To our best of knowledge, the current study is the first to directly compare the results of TAA in elderly patients (age > 70) to middle-
aged patients (age 50–60) using both clinical patient-reported outcome scores as well as objective functional measurements with gait analysis to measure physical performance. The nature and magnitude of the improvements in clinical outcome scores in this study are compatible with previous reports [34,40–42]. In this study, temporal-spatial, kinematic and kinematic parameters improved following TAA in both groups in character and amount comparable to multiple previous reports in the literature on the affect of ankle arthroplasty on gait metrics [3,10,17,22,26,43]. This was important to confirm that the objective results were within expected range, prior to making the comparative analysis according to age groups separated by almost 20 years. In this study, the older patient group had an increase in both plantar flexion and dorsiflexion, while for the younger patient group only dorsiflexion increased. We are uncertain to what this difference between the groups should be attributed. Choi et al. [26] reported on 21 patients treated with a fixed bearing prosthesis in which most of the increase in motion occurred in the range of dorsiflexion, while Brodsky et al. [22] who studied 50 patients after STAR ankle arthroplasty, and Hahn et al. [17] who studied 9 patients after a fixed-bearing ankle arthroplasty, found that most of the increase occurred in plantarflexion. Whether these differences are related to variations in prosthetic design, surgical instrumentation, or the vagaries of surgical technique is unknown. Several weaknesses of study should be recognized. First, these groups were sequential, and not randomly selected. This, by definition may result in inherent selection bias. Also some unrevealed bias is possible, such as younger patients with endstage ankle arthritis may have a history of greater activity level, or more recent ligament injury. Second, this work provides no comparison to other surgical alternatives such as ankle
Please cite this article in press as: S. Tenenbaum, et al., Functional and clinical outcomes of total ankle arthroplasty in elderly compared to younger patients, Foot Ankle Surg (2016), http://dx.doi.org/10.1016/j.fas.2016.09.005
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arthrodesis. Third, no data was collected on the speed of recovery or adverse events, although no patients were excluded for implant failure, removal or revision of the arthroplasty. Last, the AOFAS Ankle–Hindfoot Score is a legacy score, whose use dates to the beginning of this series in 1999, and precedes the current era that emphasizes validated scores, like the VAS pain scale, and the SF-36, but it was included for consistency, and for comparison to the many prior published studies which have reported results using it. Both patient age groups had improvements in clinical outcome scores and in functional metrics of ambulation following total ankle arthroplasty. Total ankle arthroplasty is valuable tool for treatment of end stage ankle arthritis when utilized in the appropriate setting, and this work reinforces the role of ankle arthroplasty when treating the elderly patient with end stage ankle arthritis. In this comparative study, it is shown that both elderly patients over the age of 70 and younger patients aged 50–60 demonstrated equivalent improvements in clinical and gait outcomes following ankle arthroplasty, which may be important data both for clinical decision-making and for the health economics for our ageing population. Conflict of interest The Authors declare they have no conflict of interest pertaining with this manuscript, including, but not limited to employment, consultancies, stock ownership, honoraria, paid expert testimony, patent applications/registrations, and grants or other funding. References [1] Bonnin M, et al. Midterm results of the Salto Total Ankle Prosthesis. Clin Orthop Relat Res 2016;2004(424):6–18. [2] Bonnin MP, Laurent JR, Casillas M. Ankle function and sports activity after total ankle arthroplasty. Foot Ankle Int 2009;30(10):933–44. [3] Dyrby C, et al. Functional evaluation of the Scandinavian Total Ankle Replacement. Foot Ankle Int 2004;25(6):377–81. [4] Gougoulias N, Khanna A, Maffulli N. How successful are current ankle replacements?: a systematic review of the literature. Clin Orthop Relat Res 2010;468(1):199–208. [5] Haddad SL, et al. Intermediate and long-term outcomes of total ankle arthroplasty and ankle arthrodesis. A systematic review of the literature. J Bone Joint Surg Am 2007;89(9):1899–905. [6] Helm R, Stevens J. Long-term results of total ankle replacement. J Arthroplasty 1986;1(4):271–7. [7] Hintermann B, et al. Total ankle replacement for treatment of end-stage osteoarthritis in elderly patients. J Aging Res 2012;2012:345237. [8] Knecht SI, et al. The Agility total ankle arthroplasty. Seven to sixteen-year follow-up. J Bone Joint Surg Am 2004;86-A(6):1161–71. [9] Kofoed H, Lundberg-Jensen A. Ankle arthroplasty in patients younger and older than 50 years: a prospective series with long-term follow-up. Foot Ankle Int 1999;20(8):501–6. [10] Queen RM, et al. J. Leonard Goldner Award 2011: changes in pain, function, and gait mechanics two years following total ankle arthroplasty performed with two modern fixed-bearing prostheses. Foot Ankle Int 2012;33(7):535–42. [11] Rouhani H, et al. Multi-segment foot kinematics after total ankle replacement and ankle arthrodesis during relatively long-distance gait. Gait Posture 2012;36(3):561–6. [12] Saltzman CL, Kadoko RG, Suh JS. Treatment of isolated ankle osteoarthritis with arthrodesis or the total ankle replacement: a comparison of early outcomes. Clin Orthop Surg 2010;2(1):1–7.
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Please cite this article in press as: S. Tenenbaum, et al., Functional and clinical outcomes of total ankle arthroplasty in elderly compared to younger patients, Foot Ankle Surg (2016), http://dx.doi.org/10.1016/j.fas.2016.09.005