CoxaPro > Clinical Library > Welcome to the joint replacement clinical library > Limb alignment in total knee arthroplasty (TKA) influences periarticular soft-tissue tension, biomechanics through knee flexion, and implant survival. Despite this, there is no uniform consensus on the optimal alignment technique for TKA. Neutral mechanical alignment facilitates knee flexion and symmetrical component wear but forces the limb into an unnatural position that alters native knee kinematics through the arc of knee flexion. Kinematic alignment aims to restore native limb alignment, but the safe ranges with this technique remain uncertain and the effects of this alignment technique on component survivorship remain unknown. Anatomical alignment aims to restore predisease limb alignment and knee geometry, but existing studies using this technique are based on cadaveric specimens or clinical trials with limited follow-up times. Functional alignment aims to restore the native plane and obliquity of the joint by manipulating implant positioning while limiting soft tissue releases, but the results of high-quality studies with long-term outcomes are still awaited. The drawbacks of existing studies on alignment include the use of surgical techniques with limited accuracy and reproducibility of achieving the planned alignment, poor correlation of intraoperative data to long-term functional outcomes and implant survivorship, and a paucity of studies on the safe ranges of limb alignment. Further studies on alignment in TKA should use surgical adjuncts (e.g. robotic technology) to help execute the planned alignment with improved accuracy, include intraoperative assessments of knee biomechanics and periarticular soft-tissue tension, and correlate alignment to long-term functional outcomes and survivorship.
BMC Musculoskelet Disord. 2018; 19: 236.

Limb alignment in total knee arthroplasty (TKA) influences periarticular soft-tissue tension, biomechanics through knee flexion, and implant survival. Despite this, there is no uniform consensus on the optimal alignment technique for TKA. Neutral mechanical alignment facilitates knee flexion and symmetrical component wear but forces the limb into an unnatural position that alters native knee kinematics through the arc of knee flexion. Kinematic alignment aims to restore native limb alignment, but the safe ranges with this technique remain uncertain and the effects of this alignment technique on component survivorship remain unknown. Anatomical alignment aims to restore predisease limb alignment and knee geometry, but existing studies using this technique are based on cadaveric specimens or clinical trials with limited follow-up times. Functional alignment aims to restore the native plane and obliquity of the joint by manipulating implant positioning while limiting soft tissue releases, but the results of high-quality studies with long-term outcomes are still awaited. The drawbacks of existing studies on alignment include the use of surgical techniques with limited accuracy and reproducibility of achieving the planned alignment, poor correlation of intraoperative data to long-term functional outcomes and implant survivorship, and a paucity of studies on the safe ranges of limb alignment. Further studies on alignment in TKA should use surgical adjuncts (e.g. robotic technology) to help execute the planned alignment with improved accuracy, include intraoperative assessments of knee biomechanics and periarticular soft-tissue tension, and correlate alignment to long-term functional outcomes and survivorship.

Justine M. Naylor,corresponding author1,2,3 Andrew Hart,1 Rajat Mittal,1 Ian A. Harris,1,2,3 and Wei Xuan1,3
Hip

Background

Inpatient rehabilitation is an expensive option following total hip arthroplasty (THA). We aimed to determine if THA patients who receive inpatient rehabilitation report better hip and quality of life scores post-surgery compared to those discharged directly home.

Methods

Prospective, propensity score matched cohort involving 12 private hospitals across five Australian States. Patients undergoing THA secondary to osteoarthritis were included. Those receiving inpatient rehabilitation for reasons other than choice or who experienced significant health events within 90-days post-surgery were excluded. Comparisons were made between those who did and did not receive inpatient rehabilitation for patient-reported hip pain and function (Oxford Hip Score, OHS) and ‘today’ health rating (EuroQol 0–100 scale). Rehabilitation provider charges were also estimated and compared.

Results

Two hundred forty-six patients (123 pairs, mean age 67 (10) yr., 66% female) were matched on 19 covariates for their propensity to receive inpatient rehabilitation. No statistically nor clinically significant between-group differences were observed [OHS median difference (IQR): 0 (− 3, 3), P = 0.60; 0 (− 1 to 1), P = 0.91, at 90 and 365-days, respectively; EuroQol scale median difference 0 (− 10, 12), P = 0.24; 0 (− 10, 10), P = 0.49; 5 (− 10, 15), P = 0.09, at 35-, 90- and 365-days, respectively]. Median rehabilitation provider charges were 10-fold higher for those who received inpatient rehabilitation [median difference $7582 (5649, 10,249), P <  0.001]. Sensitivity analyses corroborated the results of the primary analyses.

Conclusion

Utilization of inpatient rehabilitation pathways following THA appears to be low value healthcare. Sustainability of inpatient rehabilitation models may be enhanced if inpatient rehabilitation is reserved for those most impaired or who have limited social supports.


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