Age

Is there a Goldilocks age for TJA? Should patients endure the pain just a little bit longer until they reach the age of 60?  Alternatively, should patients hurry up and get their joint replaced before they get too old?  Like everything in medicine, a pure numeric threshold is just artifice, and patient specific factors must drive clinical decisions.  Yet broader trends help to inform decisions and so we examine the impact of age on TJA.

Older patients (>80 years old).

Patients > 80 years old achieve improved pain and improved function similar to patients in their 60s and 70s. One study looked at people in their 90s and found that they too improved significantly with pain and function after TKA, and therefore, age alone should not prevent people from getting a surgery that can improve quality of life [1, 2].  

Yet it is seen that older patients are more likely to have other medical conditions (including atrial fibrillation, high blood pressure etc) that can complicate recovery.  There are reports of higher complication rates after surgery due to these medical conditions.  One study suggested that the risk of death after surgery was 3x higher, the risk of MI or other cardiac complication was 2.5x higher, and the risk of pneumonia was 3.5x higher. [3]  Another study looking 1 year mortality risk saw 5% in 90 year olds, 3% in 80 year olds and 0.8% in younger patients (not all of this is attributed to the surgery because the overall mortality rate for all 90 year olds is 12% at 1 year...which is actually higher than those undergoing surgery probably because those cleared for surgery are healthier)  [4, 5]. This significant increased risk is important to remember because a hip and knee replacement surgery is life-improving but not life-saving and therefore patients need to know that the surgery can be considerable more life-threatening in patients older than 80 [6, 7].  

The length of hospitalization is also longer (3.4 days for 90s, 3.3 days for 80s, and 2.8 days for < 80). 

Younger Patients (<55 years old)

The average age for a joint replacement is about 70 years old.  But < 55 is the vastest growing group undergoing TJA.  In 2007 only 6% of TKAs were performed in patients under 50 years old [8]. 

The etiology for TJA in young patients is significantly different than in the elderly. The incidence of primary osteoarthritis is less common, with over 50% presenting for other reasons such as AVN, post-traumatic arthritis (30% of cases in TKA), and inflammatory arthritis, which at baseline are all associated with higher complication rates.

In TKA, many studies suggest good mid-term (5-10 yr) survival of 95-99% [9].  Yet other studies suggest the mid-term (7 year) revision rate is higher than average, about 8%, most commonly due to aspetic loosening and deep infection [10] [11] [12]. Survivorship appears lower than the overall TKA population, and the rate of early aspetic loosening may be 4x higher.  The Australian registry reported 12% revision rate at 10 years for patients with TKA under 55 yo. The Kaiser registry showed 2x higher revision rate in younger patients [13].  

In THA, mid-term (10 year) survivorship, for cementless implants using highly crosslinked poly, appears equivalent to older THA population [14, 15], with wear rates of 0.02 mm/yr.  Long-term revision rate (18 year avg) in patients under 50 yo was about 80%, with 95% survival of the femoral component and 85% survival of the acetabular component [16] [17] [18].  These figures reflect survival using contemporary cementless implants, while survival rates of cemented/older designs appears notably inferior [19].  Some studies report accelerated poly wear rates of 0.2 mm/yr (due to increased activity) [16], while other studies have looked at activity levels in THA under 50 yo and found activity level (1.2 millino gait cycles/yr) and wear rates (0.1mm/yr)  comparable to older counterparts [20].

The higher revision rate may be predisposed due to the underlying cause for TJA, such as posttraumatic arthritis.  Others argue that younger patients are more active and thus place greater demands on the implants, accelerating the wear.  However, studies have shown that young patients are not uniformly more active, and that there is significant variability among young patients[21, 22].  In THA about 37% returned to recreational sports (impact activity), yet for TKA only 10% returned to such activities.  Furthermore, in THA, the use of HXLPE has reduced wear to levels similar to average population age.

It appears that at 10 years after UKA in patients under 60 years old, 90% survival compared with 96% in people over 60 years old [23].  

One issue is that younger patients have higher expectations than older patients [24], appear more sensitive to residual symptoms [25], and found that age is the most important preoperative characteristic that predicts postop patient-reported outcomes [26].

REFERENCES

1.         Brander, V.A., et al., Outcome of hip and knee arthroplasty in persons aged 80 years and older. Clin Orthop Relat Res, 1997(345): p. 67-78.

2.         Kennedy, J.W., et al., Outcomes of total hip arthroplasty in the octogenarian population. Surgeon, 2013. 11(4): p. 199-204.

3.         Berend, M.E., et al., Total joint arthroplasty in the extremely elderly: hip and knee arthroplasty after entering the 89th year of life. J Arthroplasty, 2003. 18(7): p. 817-21.

4.         Belmar, C.J., et al., Total knee arthroplasty in patients 90 years of age and older. J Arthroplasty, 1999. 14(8): p. 911-4.

5.         Birdsall, P.D., et al., Health outcome after total knee replacement in the very elderly. J Bone Joint Surg Br, 1999. 81(4): p. 660-2.

6.         Kreder, H.J., et al., Arthroplasty in the octogenarian: quantifying the risks. J Arthroplasty, 2005. 20(3): p. 289-93.

7.         Miric, A., et al., Are Nonagenarians Too Old For Total Hip Arthroplasty? An Evaluation of Morbidity and Mortality Within a Total Joint Replacement Registry. J Arthroplasty, 2015. 30(8): p. 1324-7.

8.         Ravi, B., et al., The changing demographics of total joint arthroplasty recipients in the United States and Ontario from 2001 to 2007. Best Pract Res Clin Rheumatol, 2012. 26(5): p. 637-47.

9.         Keeney, J.A., et al., What is the evidence for total knee arthroplasty in young patients?: a systematic review of the literature. Clin Orthop Relat Res, 2011. 469(2): p. 574-83.

10.       Castagnini, F., et al., Total Knee Replacement in Young Patients: Survival and Causes of Revision in a Registry Population. J Arthroplasty, 2017. 32(11): p. 3368-3372.

11.       Meftah, M., et al., Long-term results of total knee arthroplasty in young and active patients with posterior stabilized design. Knee, 2016. 23(2): p. 318-21.

12.       Meehan, J.P., et al., Younger age is associated with a higher risk of early periprosthetic joint infection and aseptic mechanical failure after total knee arthroplasty. J Bone Joint Surg Am, 2014. 96(7): p. 529-35.

13.       Paxton, E.W., et al., The kaiser permanente national total joint replacement registry. Perm J, 2008. 12(3): p. 12-6.

14.       Babovic, N. and R.T. Trousdale, Total hip arthroplasty using highly cross-linked polyethylene in patients younger than 50 years with minimum 10-year follow-up. J Arthroplasty, 2013. 28(5): p. 815-7.

15.       Crowther, J.D. and P.F. Lachiewicz, Survival and polyethylene wear of porous-coated acetabular components in patients less than fifty years old: results at nine to fourteen years. J Bone Joint Surg Am, 2002. 84-A(5): p. 729-35.

16.       Kim, Y.H., et al., Comparison of total hip replacement with and without cement in patients younger than 50 years of age: the results at 18 years. J Bone Joint Surg Br, 2011. 93(4): p. 449-55.

17.       Smith, S.E., D.M. Estok, 2nd, and W.H. Harris, 20-year experience with cemented primary and conversion total hip arthroplasty using so-called second-generation cementing techniques in patients aged 50 years or younger. J Arthroplasty, 2000. 15(3): p. 263-73.

18.       Kim, Y.H., S.H. Oh, and J.S. Kim, Primary total hip arthroplasty with a second-generation cementless total hip prosthesis in patients younger than fifty years of age. J Bone Joint Surg Am, 2003. 85-A(1): p. 109-14.

19.       Dorr, L.D., T.J. Kane, 3rd, and J.P. Conaty, Long-term results of cemented total hip arthroplasty in patients 45 years old or younger. A 16-year follow-up study. J Arthroplasty, 1994. 9(5): p. 453-6.

20.       Sechriest, V.F., 2nd, et al., Activity level in young patients with primary total hip arthroplasty: a 5-year minimum follow-up. J Arthroplasty, 2007. 22(1): p. 39-47.

21.       Keeney, J.A., et al., Are younger patients undergoing TKAs appropriately characterized as active? Clin Orthop Relat Res, 2014. 472(4): p. 1210-6.

22.       Keeney, J.A., et al., Are younger patients undergoing THA appropriately characterized as active? Clin Orthop Relat Res, 2015. 473(3): p. 1083-92.

23.       Price, A.J., et al., Oxford medial unicompartmental knee arthroplasty in patients younger and older than 60 years of age. J Bone Joint Surg Br, 2005. 87(11): p. 1488-92.

24.       Von Keudell, A., et al., Patient satisfaction after primary total and unicompartmental knee arthroplasty: an age-dependent analysis. Knee, 2014. 21(1): p. 180-4.

25.       Parvizi, J., et al., High level of residual symptoms in young patients after total knee arthroplasty. Clin Orthop Relat Res, 2014. 472(1): p. 133-7.

26.       Behrend, H., et al., Factors Predicting the Forgotten Joint Score After Total Knee Arthroplasty. J Arthroplasty, 2016. 31(9): p. 1927-32.