The effects of patellar tendon advancement on the immature proximal tibia

Abstract

Purpose The aim of this study is to examine the shortterm effects of patellar tendon advancement on the proximal tibial slope in the skeletally immature patient. Methods A retrospective, non-randomized, comparative cohort design was used. Koshino indices and tibial slopes were assessed pre-operatively and post-operatively and compared with age-and sex-matched controls. Results Nine children with 17 patellar tendon advancements were analyzed for changes in Koshino indices. Of these 17 tibiae, radiographs on changes in tibial slope were available for 16 tibiae which were also compared with controls. Children aged \11 years had a greater initial posterior tibial slope (69.8°± 3.5°) than age-matched controls (80.3°± 2.7°). A decrease in posterior slope was seen in these younger patients (average change 10.3°± 4.8°) at an average of 1.6 years of follow-up. Of the nine apophyses in children aged \11 years of age, seven had undergone premature closure. ConclusionPatellar tendon advancement appears to have an unreported effect on the proximal tibial growth in the young patient (\11 years old). These patients appear to be susceptible to apophyseal closure, resulting in subsequent loss of posterior tibial slope. Surgeons should be aware of this effect and monitor younger patients with radiographs if performing this procedure.

The coupled effects of crouch gait and patella alta on tibiofemoral and patellofemoral cartilage loading in children

“…While the two-fold increase in tibiofemoral pressure from normal to severe crouch was more modest, there was a marked, and progressive, posterior migration of the contact location on the tibial plateaus from mild to severe crouch (Figure 5). This result lends credence to the belief that abnormal mechanical loading of tibiofemoral joint, and hence the underlying physis, may contribute to the abnormal posterior tibial slope seen in children who exhibit crouch gait [10].…”

“…Thus, our analysis suggests that placing the patella in a normal, or even slightly alta, position may be beneficial both to enhance moment arms [14] and to normalize the patellar contact location if patients are performing high flexion activities such as stair climbing, rising from a chair, or walking in moderate or severe crouch despite surgery. Finally, our model prediction of a posterior shift in tibial plateau loading with increasing crouch severity may have implications for long-term cartilage health [43] and skeletal growth in developing children [10]. Indeed, a prior study found that children who were treated with a distal femoral extension osteotomy for crouch exhibited a reduction in the posterior tibial slope [10], which our models suggest could arise from the contact pressure moving anteriorly on the tibial plateau as a more upright gait is achieved (Figure 5).…”

“…Prior studies have examined tibiofemoral loading in flexed postures [7,8] and crouch gait [9], with the latter study suggesting that tibiofemoral contact forces are as much as ~2.2 times higher in severe crouch than normal walking. It is speculated that crouch may also excessively load the posterior tibia, contributing to abnormal posterior slope of the tibial plateau [10]. However, traditional gait models lack the anatomical fidelity needed to assess the influence of crouch on knee cartilage pressure magnitudes and locations.…”

“…However, it is unclear how patella baja alters patellar contact pressure magnitude or location during gait. Furthermore, treatment of crouch with PTA results in reduced posterior tibal slope, especially in younger children [10]. Yet, it remains unknown whether this might be caused by alterations in tibial cartilage loading patterns.…”

The effect of distal femoral extension osteotomy on muscle lengths after surgery

“…Of particular interest is the effects of DFEO on cartilage loading patterns, which have been theorised to contribute to changes in tibial slope post-operatively in skeletally immature patients. 33 …”