Orthopedics

Tips & Techniques 

Age-Related Outcome of Mobile-Bearing Total Ankle Replacement

Federico G. Usuelli, MD; Camilla Maccario, MD; Riccardo D'Ambrosi, MD; Michele F. Surace, MD; Ettore Vulcano, MD

Abstract

The aim of this study was to investigate clinical and radiographic outcomes in patients 50 years and younger vs patients older than 50 years undergoing total ankle replacement. Seventy consecutive patients who underwent primary total ankle replacement were included in this retrospective study. Patients were assessed clinically and radiographically. There was a statistically significant difference between the 2 groups for the American Orthopaedic Foot & Ankle Society score at final follow-up. The younger group had significantly greater improvement compared with the older group. Total ankle arthroplasty is an effective treatment for young, active patients with symptomatic end-stage ankle arthritis. [Orthopedics. 2017; 40(3):e567–e573.]

Abstract

The aim of this study was to investigate clinical and radiographic outcomes in patients 50 years and younger vs patients older than 50 years undergoing total ankle replacement. Seventy consecutive patients who underwent primary total ankle replacement were included in this retrospective study. Patients were assessed clinically and radiographically. There was a statistically significant difference between the 2 groups for the American Orthopaedic Foot & Ankle Society score at final follow-up. The younger group had significantly greater improvement compared with the older group. Total ankle arthroplasty is an effective treatment for young, active patients with symptomatic end-stage ankle arthritis. [Orthopedics. 2017; 40(3):e567–e573.]

End-stage ankle osteoarthritis is a debilitating condition that results in functional limitations and a poor quality of life.1,2 The physical disability from ankle arthritis as quantified by generic outcome scales is equivalent to that for major medical conditions such as coronary artery disease, hemodialysis, hip osteoarthritis, or cervical spine pain with radiculopathy.1,3 Approximately 1% of the world's population has this pathology, and more than 70% of cases are related to posttraumatic osteoarthritis. Ankle arthritis often affects patients at a younger age than hip and knee arthritis.4,5

Ankle arthrodesis and total ankle replacement are the standard treatments when conservative treatment has failed.6 For many years, ankle arthrodesis has been the gold standard treatment for end-stage ankle arthritis. Nonetheless, it is associated with nonunions, mal-unions, gait abnormalities, and adjacent joint osteoarthritis.6 Hindfoot arthritis rates of 50% at 8 years7 and close to 100% at 22 years8 after ankle fusion have been reported.

Total ankle replacement continues to evolve as a reliable alternative to fusion in patients with end-stage ankle arthritis.9 This is in part related to the advances in design, technology, and technique that have led to improved outcomes after total ankle replacement.10,11 The ideal candidate to receive a total ankle replacement remains unclear. For many years, patients older than 50 years with a body mass index below 30 kg/m2 and low functional demands were considered the ideal candidates.12 However, these criteria were based on a few scientific studies involving older total ankle replacement designs.12 This is in contrast to the experience with total hip and knee replacements. These have been successfully performed in pediatric patients and young adults, with revision rates comparable to those in the elderly.13,14

Age-related studies of total ankle replacement have had contradictory outcomes. A study comparing patients younger than 50 years (n=31) with patients 50 years and older (n=72) at a mean follow-up of 41 months found similar outcomes and survivorship between the 2 groups.15 Another study reported a significantly increased risk of revision in younger patients. In that 10-year follow-up study of 531 primary total ankle replacements from the Swedish Ankle Arthroplasty Register, younger age at index surgery implied increased risk of revision, whereas diagnosis or gender did not.16

The aim of this study was to investigate clinical and radiographic outcomes in patients 50 years and younger vs patients older than 50 years undergoing a Hintegra (Integra, Plainsboro, New Jersey) total ankle replacement.

Materials and Methods

Institutional review board approval was obtained for this study. Each patient provided informed consent.

Between May 2011 and April 2014, 70 consecutive total ankle replacements were performed in 70 patients affected by symptomatic end-stage ankle osteoarthritis. In each case, the cementless Hintegra prosthesis was used by 2 orthopedic foot and ankle surgeons (F.G.U., C.M.).

The indications for total ankle replacement were primary degenerative osteoarthritis in 5 ankles, rheumatoid arthritis in 3 ankles, and secondary osteoarthritis (posttraumatic arthritis, hemophilia, or hereditary hemochromatosis) in 62 ankles. Exclusion criteria were neuropathic arthropathy, neuromuscular disorders, pathologic joint laxity, local or systemic infection, and avascular necrosis of the talus involving greater than 50% of the bone. All total ankle replacements were performed by one of the authors (F.G.U.) using a previously described surgical procedure.17

These 70 patients (70 ankles) were divided into 2 groups: the younger group (YG), being 50 years and younger, and the older group (OG), being older than 50 years. There were 21 and 49 patients in the YG and the OG, respectively. Minimum follow-up was 24 months.

Mean age was 41 years (range, 27–48 years) in the YG and 67 years (range, 51–83 years) in the OG. In the YG, 28.6% were women and 71.4% were men. In the OG group, 46.9% were women and 53.1% were men.

Clinical and radiographic outcomes and complications were compared between the 2 groups. Complications were subdivided into minor and major.18 Minor complications were managed without further surgery, whereas major complications were those that required additional surgery.

Clinical Evaluation

Clinical evaluation was performed preoperatively, 3 and 6 months postoperatively, and then annually.

Clinical outcome was assessed by 2 orthopedic surgeons who were not directly involved with the surgical procedure. The Short Form (SF)-12 Quality of Life score and the American Orthopaedic Foot & Ankle Society (AOFAS) score were obtained for all patients.

Pain was rated using the visual analog scale (VAS), ranging from 0 (no pain) to 10 (maximum pain). Functional results were assessed by measuring the ankle range of motion. Range of motion was determined using a goniometer along the lateral border of the leg with respect to the lateral border of the foot. Postoperative complications and need for additional procedures were recorded.

Radiographic Analysis

Radiographic examination included weight-bearing anteroposterior and lateral radiographs of the ankle obtained preoperatively, 3 and 6 months postoperatively, and then annually.

Radiographic measurements were performed digitally using the Picture Archiving and Communication System (Fujifilm, Tokyo, Japan) and were evaluated by 2 reviewers who were not directly involved with the surgical procedure.

Preoperatively, the anterior distal tibial angle (normal, 80°±3°)13 was measured on the lateral view and the lateral distal tibial angle (normal, 92.4°±3.1°) was measured on the anteroposterior view.17,18

Postoperatively, radiographic analysis was performed using the criteria described by Barg et al.17

Alpha was defined as the angle between the anatomical axis of the tibia and the articular surface of the tibial component on anteroposterior radiographs (normal, 90°±2°) (Figure 1). Beta was defined as the angle between the anatomical axis of the tibia and the articular surface of the tibial component on lateral radiographs (normal, 85°±2°) (Figure 2).


Alpha angle. On the anteroposterior radiograph, the alpha angle is formed from the longitudinal axis of the tibia and the articular surface of the tibial component.

Figure 1:

Alpha angle. On the anteroposterior radiograph, the alpha angle is formed from the longitudinal axis of the tibia and the articular surface of the tibial component.


Beta angle. On the lateral radiograph, the beta angle is formed from the longitudinal axis of the tibia and the articular surface of the tibial component.

Figure 2:

Beta angle. On the lateral radiograph, the beta angle is formed from the longitudinal axis of the tibia and the articular surface of the tibial component.

Anteroposterior tibial–talar alignment was quantified using the tibio–talar ratio (normal, 34.8%±3.8%) on pre- and postoperative lateral ankle radiographs (Figure 3).19,20


Tibio–talar ratio. A talar reference line is drawn parallel to the floor from the posterior talar point (defined as the intersection between the posterosuperior calcaneal cortex and the posterior subtalar articular surface) to the anterior talar point (vertical projection of the most anterior point of the talus onto the talar reference line). Next, the distal tibial axis is the line drawn between the midpoint of the distal tibial shaft measured 5 and 10 cm above the ankle. This divides the talar reference line into anterior and posterior segments. The tibio–talar ratio is the ratio of the length of the posterior segment of the talus (AC) to the length of the longitudinal talar (AB), expressed as a percentage.

Figure 3:

Tibio–talar ratio. A talar reference line is drawn parallel to the floor from the posterior talar point (defined as the intersection between the posterosuperior calcaneal cortex and the posterior subtalar articular surface) to the anterior talar point (vertical projection of the most anterior point of the talus onto the talar reference line). Next, the distal tibial axis is the line drawn between the midpoint of the distal tibial shaft measured 5 and 10 cm above the ankle. This divides the talar reference line into anterior and posterior segments. The tibio–talar ratio is the ratio of the length of the posterior segment of the talus (AC) to the length of the longitudinal talar (AB), expressed as a percentage.

Statistical Analysis

Statistical analysis was performed using Matlab version 2008 (MathWorks, Natick, Massachusetts) for Windows at 32 bit and involved 70 patients—29 women (41.43%) and 41 men (58.57%)—with an average age of 59 years (±14 years). Analysis of variance and the kappa test were performed. For kappa score, 95% confidence intervals were defined. All statistical tests were considered significant at P<.05.

Results

Clinical and Functional Results

Preoperative and postoperative AOFAS, SF-12, and VAS scores are presented in Table 1.


Pre- and Postoperative Clinical Outcomes

Table 1:

Pre- and Postoperative Clinical Outcomes

Patients in the 2 age groups had roughly equivalent mean preoperative VAS and SF-12 scores. A significant increase in the AOFAS and SF-12 scores and decrease in VAS scores was seen in both groups from preoperatively to final follow-up (P<.001). Preoperative AOFAS score was significantly lower in the YG (mean, 28.4±12.2 points) than in the OG (mean, 33.8±11.7 points) (P<.05) (Tables 23). There was a statistically significant difference between the YG and the OG for AOFAS score at final followup. The YG had significantly greater improvement compared with the OG (P=.046).


Preoperative Comparison of the 2 Groups

Table 2:

Preoperative Comparison of the 2 Groups


Two-Year Follow-up Comparison of the 2 Groups

Table 3:

Two-Year Follow-up Comparison of the 2 Groups

Radiographic Results

Radiographic findings are summarized in Table 4. There was no statistically significant difference in the coronal and sagittal alignments of the 2 groups. In both groups, the mean postoperative angles showed significant improvement over mean preoperative angles.


Radiographic Prosthesis Alignment

Table 4:

Radiographic Prosthesis Alignment

Complications and Additional Procedures

Additional procedures were performed at the time of the index surgery to address malalignment, muscle contractures, instability, surrounding joint arthritis, and foot deformity. In the YG and the OG, additional procedures were performed in 5 patients (23.8%) and 11 patients (22.5%), respectively. The most commonly performed additional procedures were percutaneous Achilles tendon lengthening (5 patients), realignment calcaneal osteotomy (3 patients), and subtalar arthrodesis (2 patients). Ligament balancing was performed as required through an isolated deltoid release (1 patient), a medial malleolar lengthening osteotomy (3 patients), and a combination of a medial malleolar lengthening osteotomy, a fibular shortening osteotomy, and a peroneal longus to brevis transfer (2 patients).

No complications occurred in the YG. Six complications (12.2%) occurred in the OG (P=.15). Four patients (5.7%) had major complications. Two patients (2.9%) had minor complications consisting of superficial wound dehiscence that was treated with antibiotics. One patient had a deep infection that was successfully treated with intravenous antibiotics and wound vacuum-assisted closure therapy.

Another patient had ankle pain 12 months postoperatively. Radiographs showed valgus malposition of the tibial component. The patient was taken to the operating room for revision of the tibial implant and exchange of the polyethylene spacer. Intraoperative tissue cultures were positive for Pseudomonas aeruginosa. The patient was treated with 6 weeks of antibiotics uneventfully.

A patient developed a deep infection 5 months postoperatively. This was treated with irrigation and debridement, polyethylene exchange, negative pressure wound therapy, and intravenous antibiotics for 8 weeks. However, at 13 months, recurrence of the infection required removal of all implants and a staged arthrodesis.

One patient had postoperative varus malalignment that required shortening of the fibula, lengthening of the medial malleolus, and polyethylene increase from 7 mm to 9 mm to restore joint balance.

Survivorship Analysis

At the 2-year follow-up, the survival rate of the prosthesis was 95.7%. Survivorship was 100% in the YG and 93.9% in the OG. This difference was not significant (P=.396).

Discussion

Total ankle replacement is often reserved for patients older than 50 years, whereas ankle fusion represents the gold standard treatment for younger patients with end-stage ankle arthritis.21,22 Posttraumatic end-stage ankle arthritis predominantly affects patients in their fifth and sixth decades of life, whereas hip and knee osteoarthritis is more commonly observed in the seventh and eighth decades of life.23

Hintermann22 observed that young patients undergoing ankle arthrodesis were at a significantly higher risk of developing symptomatic surrounding joint arthritis during a 20-year period.

There are only a few studies comparing the outcome of total ankle replacement in young patients with that in elderly patients. These studies have observed lower survivorship rates for younger patients.6,16,24,25 Spirt et al,25 on comparing patients younger than 54 years with patients older than 54 years at a mean follow-up of 33 months, reported a survivorship rate of 74% in the younger group and 89% in the older group. They also reported a 1.45 times higher rate of reoperation and a 2.65 times greater risk of implant failure in the younger group.25 In a Swedish study, younger age was associated with osteolysis, loosening, and a subsequent increased risk of later revision.16

These findings are in contrast to those from survivorship studies of total hip and knee replacements, which have reported comparable rates of implant failure and revision in younger and older patients.26–28 Conversely, Kofoed and Lundberg-Jensen29 reported similar survivorship rates when analyzing first- and second-generation ankle replacements in patients younger than 50 years (group A, 30 ankles) and patients 50 years and older (group B, 70 ankles). Group A had 75% implant survival and group B had 80.6% implant survival at a mean of 6 years.29

Valderrabano et al10 found that patient age did not affect functional outcomes at almost 4 years after index surgery. Skyttä et al,30 on analyzing 573 primary total ankle replacements from the Finnish Arthroplasty Register with a mean follow-up of more than 2 years, reported that age and sex did not have a statistically significant effect on survivorship of the implants. In a study of 257 primary ankle replacements at a mean follow-up of 4 years, Fevang et al31 observed no significant impact of age, sex, type of prosthesis, diagnosis, or year of operation on the risk of revision.

Demetracopoulos et al32 studied 395 consecutive patients divided into 3 groups based on age (<55, 55 to 70, and >70 years) at the time of surgery. At a mean follow-up of 3.5 years (range, 2–5.4 years), the outcomes of ankle replacement were similar between younger patients and older patients.32

In a study of 103 total ankle replacements, Rodrigues-Pinto et al15 divided patients into 2 groups based on age: younger than 50 years (n=31) and 50 years and older (n=72). They observed that total ankle arthroplasty was an effective treatment for young, active patients with end-stage ankle arthritis. Specifically, they reported better clinical outcomes and similar survivorship rates compared with ankle replacements performed in older, less active patients.

The rationale for the current study was that ankle arthrodesis for the treatment of end-stage osteoarthritis in young patients has been associated with significantly poorer results and lower patient satisfaction scores.33 Younger patients will most likely live longer and therefore may require ankle revision surgery. Nonetheless, ankle arthroplasty buys time and allows for a good quality of life while sparing adjacent joints from progressive degeneration.

In the current study, no clinical, functional, or radiographic differences were found between the 2 age groups. Although the younger patients had worse preoperative AOFAS scores, these were significantly higher postoperatively than those of the older patients. Also, complications were more common in the older group. Moreover, major complications and survivorship rates were not statistically different between the 2 groups, in contrast with the findings of Spirt et al.25

The current findings must be interpreted with caution. Patient selection may have an impact on postoperative outcome. It remains unclear whether younger patient age and preoperative ankle deformity play a role in functional outcome and implant survival. Doets et al34 reported an increased failure rate in ankles with a preoperative deformity greater than 10° in the frontal plane. Seventeen ankles with a preoperative varus or valgus deformity greater than 10° had a mean overall survival rate of 48% at 8 years. Ankles with a neutral alignment preoperatively (<10° of varus or valgus) had a mean overall survival rate of 90% at 8 years.34 Conversely, others have observed good outcomes and survival of total ankle replacements when deformity was addressed by experienced surgeons prior to or during arthroplasty.13,35–37

Limitations of the current study included the small cohort, the short follow-up, and the use of a nonvalidated questionnaire (ie, AOFAS score). Despite 2-year follow-up, Wood et al37 observed that total ankle replacements mostly (12%) failed within the first 48 months postoperatively.

Conclusion

The authors found that total ankle arthroplasty was an effective short-term treatment for young, active patients with symptomatic end-stage ankle arthritis. The outcomes in young patients were comparable to those in older, less active patients—the standard candidates for this procedure to date. Indeed, the authors' findings disagree with the widespread theory that ankle replacement is a more reliable treatment for the elderly. Larger studies with longer followup are necessary to form new and solid recommendations to consider younger patients and active patients good candidates for total ankle replacement.

References

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Pre- and Postoperative Clinical Outcomes

ScorePreoperative6 Months Postoperative12 Months Postoperative24 Months PostoperativeANOVA P




MeanSDMeanSDMeanSDMeanSD
Total population
  AOFAS32.212.152.315.472.113.272.315.9<.0001
  VAS8.91.54.51.72.21.62.51.9<.0001
  PCS34.45.241.13.945.46.244.97.5<.0001
  MCS39.4650.57.451651.77.3<.0001
Younger group
  AOFAS28.412.254.112.976.510.677.311.1<.0001
  VAS8.41.74.322.11.63.41.5<.0001
  PCS34.15.640.93.246.26.246.88<.0001
  MCS38.26.949.0751.24.652.76.7<.0001
Older group
  AOFAS33.811.751.516.270.313.770.217.2<.0001
  VAS9.11.34.61.72.31.62.52<.0001
  PCS34.65.141.24.145.16.244.37.3<.0001
  MCS39.325.5751.097.550.866.4751.387.53<.0001

Preoperative Comparison of the 2 Groups

Clinical MeasureYounger GroupOlder Group
AOFAS score
  Mean28.433.8
  SD12.211.7
   P.046
VAS score
  Mean8.49.1
  SD1.71.3
   P.053
PCS score
  Mean34.134.6
  SD5.65.1
   P.361
MCS score
  Mean38.239.3
  SD6.95.6
   P.147

Two-Year Follow-up Comparison of the 2 Groups

Clinical MeasureYounger GroupOlder Group
AOFAS score
  Mean77.370.2
  SD11.117.6
   P.046
VAS score
  Mean3.42.5
  SD1.52
   P.368
PCS score
  Mean46.844.3
  SD87.3
   P.163
MCS score
  Mean52.751.4
  SD6.77.5
   P.294

Radiographic Prosthesis Alignment

MeasurementPreoperative6 Months Postoperative12 Months Postoperative24 Months PostoperativeTest (A) - Test (T) P




MeanSDMeanSDMeanSDMeanSD
Total
  LDTA angle91.4°5.4°------.487 (A)
  ADTA angle84°6.2°------.0025 (A)
  Alpha angle--91.5°3.9°91.6°3.7°91.3°3.2°
  Beta angle--86.2°3.2°85.7°3.2°86.9°3.1°
  TT ratio0.4%0.1%0.4%0.1%0.4%0.1%0.4%0.1%.0101 (T)
Younger group
  LDTA angle90.8°4.1°------.420 (A)
  ADTA angle83.4°5.6°------.043 (A)
  Alpha angle--91.6°2.9°91.4°91.0°2.5°
  Beta angle--85.7°86.8°3.9°86.4°2.6°
  TT ratio0.4%0.1%0.4%0.1%0.4%0.1%0.4%0.1%.289 (T)
Older group
  LDTA angle91.6°5.8°------.432 (A)
  ADTA angle84.2°6.5°------<.0001 (A)
  Alpha angle--91.4°4.2°91.7°3.9°91.4°3.4°
  Beta angle--86.4°3.3°86.6°2.8°86.8°3.3°
  TT ratio0.4%0.1%0.4%0.1%0.4%0.1%0.4%0.1%.0022 (T)
Authors

The authors are from the Foot and Ankle Service (FGU, CM, RD), IRCCS Istituto Ortopedico Galeazzi, Milan, and the Department of Orthopaedics (MFS), University of Insubria, Varese, Italy; and the Department of Orthopaedics (EV), Icahn School of Medicine at Mount Sinai, New York, New York.

Drs Maccario, D'Ambrosi, Surace, and Vulcano have no relevant financial relationships to disclose. Dr Usuelli is a paid consultant for Integra and Zimmer and has received grants from Zimmer.

Correspondence should be addressed to: Ettore Vulcano, MD, Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, 1000 10th Ave, Ste 3A-35, New York, NY 10019 ( ettorevulcano@hotmail.com).

Received: March 06, 2017
Accepted: March 10, 2017
Posted Online: March 31, 2017

10.3928/01477447-20170327-05

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