Effects of different foot progression angles and platform settings on postural stability and fall risk in healthy and medial knee osteoarthritic adults

Double Level Knee Derotational Osteotomy Yields Better Postoperative Outcomes than Tibial Tubercle Transfer Combined with Medial Patellofemoral Ligament Reconstruction in Patients with Recurrent Patellar Instability and Severe Malrotation

PURPOSE

To assess the postoperative outcomes of double level knee derotational osteotomy (KDRO) combined with medial patellofemoral ligament reconstruction (MPFLR), and to compare it with tibial tuber transfer (TTT) and MPFLR without derotational osteotomy in patients with recurrent patellar instability (RPI) and a marked torsional deformity.

METHODS

From March 2020 to December 2021, patients with torsion deformity (combined femoral torsion and tibial torsion ≥ 30°) were retrospectively included. The minimum follow-up time was 18 months. Patients received KDRO and MPFLR were categorized into KDRO group and patients received a combined TTT and MPFLR were categorized into control group. Preoperative and postoperative clinical symptoms, patient-reported outcomes (PROs) (Kujala, visual analogue scale [VAS], Lysholm, International Knee Documentation Committee [IKDC], Tegner, and Knee Injury and Osteoarthritis Outcome [KOOS] scores) and imaging parameters (femoral torsion, tibial torsion, patellar height, femoral trochlear dysplasia, congruence angle, patellar tilt angle, lateral patellar angle, lateral patellar translation, and tibial tubercle-trochlear groove distance) were analyzed.

RESULTS

In all, 36 patients were included with 18 in KDRO group and 18 in control group. The mean follow-up time was 30 (range 21-39) months. At the latest follow-up, no patient experienced re-dislocation in either group. Except for the femoral torsion and tibial torsion in the control group, postoperative imaging parameters were significantly reduced to the normal range. KDRO group has a lower patellar tilt angle (P=.043, effect size 0.64). All clinical scores in both groups significantly improved postoperatively. KDRO group has better functional scores than control group except the KOOS daily living activities subscore and the KOOS sports and recreation subscore. More proportions of patients in KDRO group met the minimal clinically important difference (MCID) for most PROs than control group. Eight patients (44%) in the control group complained of postoperative anterior knee pain, compared with 1 patient (6%) in KDRO group (P=.018).

CONCLUSION

KDRO combined with MPFLR was associated with better postoperative outcomes than TTT combined with MPFLR in patients with RPI and a torsion deformity.

Internal Torsion of the Knee: An Embodiment of Lower-Extremity Malrotation in Patients with Patellar Instability

BACKGROUND

Torsion of the lower extremities has been suggested to be a predisposing factor for patellar instability. However, no clear torsional factors have been clarified. This study aimed to elucidate the rotational geometry of the lower limb through segmental analysis in patients with patellar instability.

METHODS

Eighty-three patients with patellar instability were included. Computed tomography of the lower limb was acquired. Femoral and tibial torsion were measured in different segments. Femoral and tibial torsion in each segment was compared between the high- and normal-torsion groups to investigate which segment contributes the most.

RESULTS

All segments of femoral and tibial torsion except proximal femoral torsion showed significant differences between the high- and normal-torsion groups. The average proximal femoral torsion was 1.9° ± 7.1°, indicating that there was only slight torsion in the segment of the femoral neck. The angle between the femoral neck and the foot orientation in the normal-torsion, high-torsion tibial, and combined high-torsion femoral and tibial groups was 89.1° ± 12.0°, 81.3° ± 9.4°, and 98.2° ± 11.7°, respectively (p < 0.001), which suggested that the femoral neck remained nearly perpendicular to the foot orientation in the normal-torsion group. Shaft and distal femoral torsion contributed the most to total femoral torsion. For tibial torsion, from distal to proximal, internal torsion of both the proximal and distal segments contributed to the high torsion. There was no significant difference between distal femoral torsion and proximal tibial torsion, which suggested that, rather than the distal femur rotating internally on its own, the distal femur and the proximal tibia simultaneously rotated internally.

CONCLUSIONS

In patients with patellar instability, torsional deformity occurs along the length of the tibia and in the shaft and distal segments of the femur. The comprehensive embodiment of lower-extremity malrotation is an internal rotation deformity of the knee.

CLINICAL RELEVANCE

This study elucidated the rotational geometry of the lower limb through a detailed segmental analysis in patients with patellar instability. It could serve as a theoretical basis for choosing a derotational osteotomy site and may be a reference for additional clinical research.

Analysis of Dynamic Plantar Pressure before and after the Occurrence of Neurogenic Intermittent Claudication in Patients with Lumbar Spinal Stenosis: An Observational Study

Lumbar spinal stenosis (LSS) is a common disease in the elderly population; it has been reported that patients with LSS have an abnormal gait pattern due to symptom such as neurogenic intermittent claudication (NIC); however, no detailed reports exist on the plantar pressure distributions in LSS patients with NIC. To analysis the plantar pressure characteristics of LSS patients, the Footscan® pressure system was used to perform dynamic plantar pressure measurements in 20 LSS patients (age, 69.5 ± 7.2 years) before and after the occurrence of NIC. The contact time (CT), foot progression angle (FPA), pressure-time integral (PTI), and contact area (CA) were collected and compared between the LSS patients and age-matched healthy subjects in each measurement. The LSS group showed an increase in forefoot CT%, PTI, and CA% in both measurements compared with those in the control group. After the occurrence of NIC in the LSS group, CT%, PTI, and CA% of the forefoot increased further compared with those before the occurrence of NIC. In addition, after the occurrence of NIC, the PTI and CA% of the forefoot shifted from the medial foot to the lateral foot. The results suggested that the plantar pressure distributions of patients with LSS differs from normal subjects due to the posture of waking with lumbar forward flexion, and the forefoot bears a higher relative load. In addition, the occurrence of NIC could affect the plantar pressure distribution of the patients with LSS, predicting the patient's risk of falling to the anterior direction and to the symptomatic side.