An Anatomically Placed Tibial Tunnel does not Completely Surround a Simulated PCL Reconstruction Graft in the Proximal Tibia

Introduction It is hypothesized that anatomic tunnel placement will create tunnels with violation of the posterior cortex and subsequently an oblique aperture that is not circumferentially surrounded by bone. In this article, we aimed to characterize posterior cruciate ligament (PCL) tibial tunnel using a three-dimensional (3D) computed tomography (CT) model. Methods Ten normal knee CTs with the patella, femur, and fibula removed were used. Simulated 11 mm PCL tibial tunnels were created at 55, 50, 45, and 40 degrees. The morphology of the posterior proximal tibial exit was examined with 3D modeling software. The length of tunnel not circumferentially covered (cortex violation) was measured to where the tibial tunnel became circumferential. The surface area and volume of the cylinder both in contact with the tibial bone and that not in contact with the tibia were determined. The percentages of the stick-out length surface area and volume not in contact with bone were calculated. Results The mean stick-out length of uncovered graft at 55, 50, 45, and 40 degrees were 26.3, 20.5, 17.3, and 12.7 mm, respectively. The mean volume of exposed graft at 55, 50, 45, and 40 degrees were 840.8, 596.2, 425.6, and 302.9 mm3, respectively. The mean percent of volume of exposed graft at 55, 50, 45, and 40 degrees were 32, 29, 25, and 24%, respectively. The mean surface of exposed graft at 55, 50, 45, and 40 degrees were 372.2, 280.4, 208.8, and 153.3 mm2, respectively. The mean percent of surface area of exposed graft at 55, 50, 45, and 40 degrees were 40, 39, 34, and 34%, respectively. Conclusion Anatomic tibial tunnel creation using standard transtibial PCL reconstruction techniques consistently risks posterior tibial cortex violation and creation of an oblique aperture posteriorly. This risk is decreased with decreasing the angle of the tibial tunnel, though the posterior cortex is still compromised with angles as low as 40 degrees. With posterior cortex violation, a surgeon should be aware that a graft within the tunnel or socket posteriorly may not be fully in contact with bone. This is especially relevant with inlay and socket techniques.

Assessment of in vivo bone activity patterns in medial mobile-bearing unicompartmental knee arthroplasty

Aims Higher osteoblastic bone activity is expected in aseptic loosening and painful unicompartmental knee arthroplasty (UKA). However, insights into normal bone activity patterns after medial UKAs are lacking. The aim of this study was to identify the evolution in bone activity pattern in well-functioning medial mobile-bearing UKAs. Methods In total, 34 patients (13 female, 21 male; mean age 62 years (41 to 79); BMI 29.7 kg/m2 (23.6 to 42.1)) with 38 medial Oxford partial UKAs (20 left, 18 right; 19 cementless, 14 cemented, and five hybrid) were prospectively followed with sequential 99mTc-hydroxymethane diphosphonate single photon emission CT (SPECT)/CT preoperatively, and at one and two years postoperatively. Changes in mean osteoblastic activity were investigated using a tracer localization scheme with volumes of interest (VOIs), reported by normalized mean tracer values. A SPECT/CT registration platform additionally explored cortical tracer evolution in zones of interest identified by previous experimental research. Results Significant reduction of tracer activity from the preoperative situation was found in femoral and anteromedial tibial VOIs adjacent to the UKA components. Temporarily increased osteoblastic bone activity was observed in VOIs comprising the UKA keel structure at one year postoperatively compared to the preoperative activity. Persistent higher tracer uptake was found in the posterior tibial cortex at final follow-up. Multivariate analysis showed no statistical difference in osteoblastic bone activity underneath cemented or cementless components. Conclusion Well-functioning medial mobile-bearing UKAs showed distinct changes in patterns of normalized bone tracer activity in the different VOIs adjacent to the prosthetic components, regardless of their type of fixation. Compared to the preoperative situation, persistent high bone activity was found underneath the keel and the posterior tibial cortex at final follow-up, with significant reduced activity only being identified in femoral and anteromedial tibial VOIs. Cite this article: Bone Joint J 2022;104-B(1):34–44.

Assessing risk of damage to posterior ankle structures during total ankle arthroplasty

Aims Arthroplasty has become increasingly popular to treat end-stage ankle arthritis. Iatrogenic posterior neurovascular and tendinous injury have been described from saw cuts. However, it is hypothesized that posterior ankle structures could be damaged by inserting tibial guide pins too deeply and be a potential cause of residual hindfoot pain. Methods The preparation steps for ankle arthroplasty were performed using the Infinity total ankle system in five right-sided cadaveric ankles. All tibial guide pins were intentionally inserted past the posterior tibial cortex for assessment. All posterior ankles were subsequently dissected, with the primary endpoint being the presence of direct contact between the structure and pin. Results All pin locations confer a risk of damaging posterior ankle structures, with all posterior ankle structures except the flexor hallucis longus tendon being contacted by at least one pin. Centrally-aligned transcortical pins were more likely to contact posteromedial neurovascular structures. Conclusion These findings support our hypothesis that tibial guide pins pose a considerable risk of contacting and potentially damaging posterior ankle structures during ankle arthroplasty. This study is the first of its kind to assess this risk in the Infinity total ankle system. Cite this article: Bone Jt Open 2021;2(7):503–508.

Tibial Cortex Transverse Distraction Combined With Debridement and Vacuum Sealing Drainage for Diabetic Foot Ulcers: Validation of Previous Published Study

Objective: Tibial cortex transverse distraction (TCTD) has been recently reported in treating diabetic foot ulcers. However, there is no further studies verifying the effectiveness. We performed TCTD combined with debridement and vacuum sealing drainage (VSD) for diabetic foot ulcers to test the effectiveness.Methods: This study includes 25 patients with diabetic foot ulcers from 3 hospitals. The ulcers of all the cases didn't heal for over 3 months. Then we performed TCTD combined with debridement and VSD for them. After the surgery, the patients were regularly followed-up for more than one year.Results: Among all the patients, one case underwent amputation because of aggravated infections. There were no cases with complication like tibia fractures. Pin-site infections occurred in 2 patients. The infected pin-site healed after changing dressings for 2 weeks. For the rest 22 patients, their ulcers healed at postoperative 8.2 ± 4.5 weeks. The postoperative visual analogue score (VAS) which indicated pain degree, reduced significantly when compared with preoperative VAS.Conclusions: When combined with other measures like debridement and VSD, TCTD can bring advantages for patients diagnosed with diabetic foot ulcers, and the trauma of this operation remains a factor to be considered.Type of study/level of evidence: Therapeutic IV.

The discovery and clinical significance of the “Twin Open Skylight and Summon Effects” of the Ilizarov tibial transverse transport technique

Ilizarov’s tibial transverse transport (TTT) technique can promote vascular regeneration. It has been used in the treatment of a variety of lower limb ischemic diseases, such as thromboangiitis obliterans, diabetic foot ulcers, etc. Recently, several novel therapeutic effects have been discovered based on TTT treatment. For instance, in the treatment of thromboangiitis obliterans, an “Open Skylight Effect” was well defined in which the symptom of resting pain disappeared following tibial cortex osteotomy (Long Qu, 2001). During the treatment of bilateral diabetic foot gangrene, patients that received TTT treatment on the one side of the lower limb were observed to have a simultaneous healing of ulcers on both sides, which was termed as the “Summon Effect” (Qikai Hua, 2017). In 2019, we characterized the above discoveries as the “Twin Open Skylight and Summon Effects”. These findings will inspire more potential clinical applications of TTT technique.