Constrained implants with intra-medullary fixation are expedient for complex TKA. Constraint is associated with loosening, but can correction of deformity mitigate risk of loosening?

Primary TKA's with a non-linked constrained prosthesis from 2010-2018 were identified. Indications were ligamentous instability or intra-medullary fixation to bypass stress risers. All included fully cemented 30mm stem extensions on tibia and femur. If soft tissue stability was achieved, a posterior stabilized (PS) tibial insert was selected.

Pre and post TKA full length radiographs showed.

77 TKA's in 68 patients, average age 69.3 years (41-89.5) with OA (65%) post-trauma (24.5%) and inflammatory arthropathy (10.5%).

Pre-op radiographs (62 knees) showed varus in 37.0% (HKAA: 4^o-29^o), valgus in 59.6% (HKAA range 8^o-41^o) and 2 knees in neutral.

13 cases deceased within 2 years were excluded. Six with 2 year follow up pending have not been revised. Mean follow-up is 6.1 yrs (2.4-11.9yrs).

Long post-op radiographs showed 34 (57.6%) in central KZ (HKKA 180^o +/- 2^o)^.

Thirteen (22.0%) were in mechanical varus (HKAA 3^o-15^o) and 12 (20.3%) in mechanical valgus: HKAA (171^o-178^o)

Three failed with infection; 2 after ORIF and one with BMI>50. The greatest post op varus suffered peri-prosthetic fracture. There was no aseptic loosening or instability.

Only full-length radiographs accurately measure alignment and very few similar studies exist. No cases failed by loosening or instability, but PPF followed persistent malalignment. Infection complicated prior ORIF and elevated BMI.

This does not endorse indiscriminate use of mechanically constrained knee prostheses. Lower demand patients with complex arthropathy, especially severe deformity, benefit from fully cemented, non-linked constrained prostheses, with intra-medullary fixation. Hinges are not necessarily indicated, and rotational constraint does not lead to loosening.

Low back pain in junior Australian Rules footballers has not been investigated, despite findings that adolescent back pain is a strong predictor for adult back pain. The aim of this study was to determine the prevalence, intensity, quality and frequency of low back pain in junior Australian Rules footballers.

A cross-sectional survey of male non-elite junior (n = 60) and elite junior players (n = 102) was conducted along with a convenience sample of non-footballers (school children) (n = 100). Subjects completed a self-reported questionnaire on low back pain incorporating the Quadruple Visual Analogue Scale and McGill Pain Questionnaire (short form), along with additional questions adapted from an Australian epidemiological study.

For current, average and best low back pain levels, elite junior players had higher pain levels (p < 0.001), with no difference noted between non-elite juniors and controls for average and best low back pain. For low back pain at worst, there were significant differences in the mean pain cores. The difference between elite juniors and non-elite juniors (p = 0.040) and between elite juniors and controls (p < 0.001) was significant, but not between non-elite juniors and controls. The chance of suffering low back pain increases from 45% for controls, through 55% for non-elite juniors to 66.7% for elite juniors. The chance that a pain sufferer experiences chronic pain is 16% for controls and 41% for non-elite junior and elite junior players. Elite junior players experienced low back pain more frequently (p = 0.002), with no difference in frequency noted between non-elite juniors and controls. Over 25% of elite junior and non-elite junior players reported that back pain impacted their performance some of the time or greater.

This study demonstrated that when compared with non-elite junior players and non-footballers of a similar age, elite junior players experience back pain more severely and frequently and have higher prevalence and chronicity rates.