Suture Anchor Versus Transosseous Tunnel Repair for Inferior Pole Patellar Fractures Treated With Partial Patellectomy and Tendon Advancement: A Biomechanical Study

Background: Comminuted inferior pole patellar fractures can be treated in numerous ways. To date, there have been no studies comparing the biomechanical properties of transosseous tunnels versus suture anchor fixation for partial patellectomy and tendon advancement of inferior pole patellar fractures. Hypothesis: Suture anchor repair will result in less gapping at the repair site. We also hypothesize no difference in load to failure between the groups. Study Design: Controlled laboratory study. Methods: Ten cadaveric knee extensor mechanisms (5 matched pairs; patella and patellar tendon) were used to simulate a fracture of the extra-articular distal pole of the patella. The distal simulated fracture fragment was excised, and the patellar tendon was advanced and repaired with either transosseous bone tunnels through the patella or 2 single-loaded suture anchors preloaded with 1 suture per anchor. Load to failure and elongation from cycles 1 to 250 between 20 and 100 N of force were measured, and modes of failure were recorded. Statistical analysis was performed using a paired 2-tailed Student t test. Results: The suture anchor group had less gapping during cyclic loading as compared with the transosseous tunnel group (mean ± SD, 6.83 ± 2.23 vs 13.30 ± 5.74 mm; P = .047). There was no statistical difference in the load to failure between the groups. The most common mode of failure was at the suture-anchor interface in the suture anchor group (4 of 5) and at the knot proximally on the patella in the transosseous tunnel group (4 of 5). Conclusion: Suture anchors yielded similar strength profiles and less tendon gapping with cyclic loading when compared with transosseous tunnels in the treatment of comminuted distal pole of the patellar fractures managed with partial patellectomy and patellar tendon advancement. Clinical Relevance: Suture anchors may offer robust repair and earlier range of motion in the treatment of fractures of the distal pole of the patella. Clinical randomized controlled trials would help clinicians better understand the difference in repair techniques and confirm the translational efficacy in clinical practice.

Type II Collagen Sponges Facilitate Tendon Stem/Progenitor Cells to Adopt More Chondrogenic Phenotypes and Promote the Regeneration of Fibrocartilage-Like Tissues in a Rabbit Partial Patellectomy Model

ObjectiveFibrocartilage transition zone (FC) is difficult to regenerate after surgical re-attachment of tendon to bone. Here, we investigated whether type II collagen-sponges (CII-sponges) facilitated tendon stem/progenitor cells (TSPCs) to adopt chondrogenic phenotypes and further observed if this material could increase the FC areas in bone-tendon junction (BTJ) injury model.MethodsCII-sponges were made as we previously described. The appearance and pore structure of CII-sponges were photographed by camera and microscopies. The viability, proliferation, and differentiation of TSPCs were examined by LIVE/DEAD assay, alamarBlue, and PKH67 in vitro tracking. Subsequently, TSPCs were seeded in CII-sponges, Matrigel or monolayer, and induced under chondrogenic medium for 7 or 14 days before being harvested for qPCR or being transplanted into nude mice to examine the chondrogenesis of TSPCs. Lastly, partial patellectomy (PP) was applied to establish the BTJ injury model. CII-sponges were interposed between the patellar fragment and tendon, and histological examination was used to assess the FC regeneration at BTJ after surgery at 8 weeks.ResultsCII-sponges were like sponges with interconnected pores. TSPCs could adhere, proliferate, and differentiate in this CII-sponge up to 14 days at least. Both qPCR and immunostaining data showed that compared with TSPCs cultured in monolayer or Matrigel, cells in CII-sponges group adopted more chondrogenic phenotypes with an overall increase of chondrocyte-related genes and proteins. Furthermore, in PP injured model, much more new formed cartilage-like tissues could be observed in CII-sponges group, evidenced by a large amount of positive proteoglycan expression and typical oval or round chondrocytes in this area.ConclusionOur study showed that CII-sponges facilitated the TSPCs to differentiate toward chondrocytes and increased the area of FCs, which suggests that CII-sponges are meaningful for the reconstruction of FC at bone tendon junction. However, the link between the two phenomena requires further research and validation.

Calcitonin Gene-Related Peptide Influences Bone-Tendon Interface Healing Through Osteogenesis: Investigation in a Rabbit Partial Patellectomy Model

Background: Calcitonin gene-related peptide (CGRP), which has been shown to play an important role in osteogenesis during fracture repair, is also widely distributed throughout the tendon and ligament. Few studies have focused on the role of CGRP in repair of the bone-tendon interface (BTI). Purpose: To explore the effect of CGRP expression on BTI healing in a rabbit partial patellectomy model. Study Design: Controlled laboratory study. Methods: A total of 60 mature rabbits were subjected to a partial patellectomy and then randomly assigned to CGRP, CGRP-antagonist, and control groups. In the CGRP-antagonist group, the CGRP receptor antagonist BIBN4096BS was administered to block CGRP receptors. The patella–patellar tendon complex was harvested at 8 and 16 weeks postoperatively and subjected to radiographic, microlaser Raman spectroscopy, histologic, and biomechanical evaluation. Results: Radiographic data showed that local CGRP expression improved the growth parameters of newly formed bone, including area and volumetric bone mineral density ( P < .05 for both). Raman spectroscopy revealed that the relative bone mineral composition increased in the CGRP group compared with in the control group and the CGRP-antagonist group ( P < .05 for both). Histologic testing revealed that the CGRP group demonstrated better integration, characterized by well-developed trabecular bone expansion from the residual patella and marrow cavity formation, at the 8- and 16-week time points. Mechanical testing demonstrated that the failure load, ultimate strength, and stiffness in the CGRP group were significantly higher than those in the control group ( P < .05 for all), whereas these parameters in the CGRP-antagonist group were significantly lower compared with those in the control group at 16 weeks after surgery ( P < .05 for all). Conclusion: Increasing the local concentration of CGRP in the early stages of BTI healing enhanced osteogenesis in a rabbit partial patellectomy model and promoted healing of the BTI injury, whereas treatment using a CGRP antagonist had the opposite effect. However, exogenous CGRP expression did not induce novel bone remolding. Clinical Relevance: CGRP may have potential as a new therapy for BTI injuries or may be added to postoperative regimens to facilitate healing.

Autologous Freeze-Dried, Platelet-Rich Plasma Carrying Icariin Enhances Bone-Tendon Healing in a Rabbit Model

Background: Tendon-bone interface (TBI) injuries are common in sports activities. Owing to the limited regenerative ability of the TBI, its functional healing remains a difficulty in clinical practice. Icariin (ICA) provides strong stimulation for osteogenesis. Platelet-rich plasma (PRP) can be used as a carrier for bioactive molecules, although its ability to provide sustained release for such molecules needs improvement. Hypothesis: Freeze-dried PRP (FD-PRP) as a carrier for ICA can provide sustained release of ICA into the tendon-bone (T-B) healing site, thus accelerating T-B healing. Study Design: Controlled laboratory study. Methods: A total of 84 New Zealand rabbits with partial patellectomy in the hindlimb were randomly allocated into 3 different treatments: ICA incorporated with FD-PRP (ICA/FD-PRP), FD-PRP alone (FD-PRP), or saline control (CTL). The rabbit patella–patellar tendon (PP) interfaces were postoperatively harvested at postoperative week 8 or 16 for gross, radiological, histological, and mechanical evaluations. Results: Our results showed that FD-PRP can act as a carrier for sustained release of ICA into the T-B healing site. Macroscopically, no signs of infection or osteoarthritis were shown in the regenerated PP interfaces, and the area of cartilaginous metaplasia in the FD-PRP and ICA/FD-PRP groups at postoperative week 16 was significantly larger than that of the CTL group ( P < .05 for all). Radiologically, micro–computed tomography showed that new bone which formed at the healing site in the ICA/FD-PRP group was significantly increased, remodeled, and mineralized in comparison with the CTL group ( P < .05 for all). Histologically, the ICA/FD-PRP group exhibited a significant native PP interface, as shown by the enlargement and remodeling of new bone, well-organized collagen fibers, and robust production of proteoglycans in the regenerated fibrocartilage. The mechanical strength of the regenerated PP interface was significantly improved in the ICA/FD-PRP group. Significantly higher failure load and stiffness were shown in the ICA/FD-PRP group compared with the CTL and FD-PRP groups, respectively ( P < .05 for all). Conclusion: FD-PRP is a suitable sustained-release carrier for ICA, and ICA/FD-PRP can provide sustained release of ICA into the T-B healing site, thus effectively accelerating T-B healing. Clinical Relevance: Findings of this study demonstrate the feasibility of using FD-PRP as a carrier for ICA to improve T-B healing and provide a foundation for future clinical application.

Surgical treatment and rehabilitation capabilities of patients with patellar fractures

Relevance. Fractures of the patella represent about 1% of all fractures of the bones. Among surgeons there is no a single approach to the treatment of patients with many fragmentary patellar fractures. After surgical treatment of patients with patellar fractures, various complications could be observed. Aside from that, there is no consensus on the treatment of complex fractures of the patella, and in practice, trauma physicians use a variety of methods of osteosynthesis of the patella. In the light of the foregoing, the study of long-term results of patients after patellar fractures is of particular relevance. Purpose of study: to examine the results of patients after surgical treatment of patellar fractures with a view to devising best practices for its osteosynthesis. Patients and methods. A study of the results of treatment of 78 patients with patellar fractures was conducted. The following groups were identified depending on the type of surgery and the nature of the fracture: Weber osteosynthesis in fragmentary fractures; «cruciform osteosynthesis» and other identical options of osteosynthesis with spokes and wires at three or more fragmented fractures of the patella; combination osteosynthesis. A comparative analysis of the results of treatment of patients after partial patellectomy and osteosynthesis of the patella with spokes and tightening wire loops was conducted. We evaluated the results on the KOOS scale with clinical examination and x-ray examination of patients. Beyond that, we have supplemented this scale with the patients’ own opinion on the evaluation of the results of their treatment. Results. The average follow-up period was 22 months. A comparative analysis of the groups of patients after surgical treatment of patellar fractures on the KOOS scale showed the best results in osteosynthesis of transverse two-fragment patellar fractures by Weber’y - 72%. The results of treatment of patients with many fragmentary patellar fractures using 3-5 spokes and 2-3 wires was - 64%; after the rehabilitation of the lower pole was - 68%) and after partial patellectomy -51%. Conclusion. If a patient has three-fragmented patellar fractures, reasonable results could be achieved by using 3 spokes and 2 tightening wire loops. With four or more fragmentary fractures of the patella, the optimal method for its osteosynthesis is the use of a «cruciform» method with 4 or more spokes in combination with two or three wire loops. The use of patellectomy with subsequent fixation of the blocking wire loop should be avoided in all types of patellar fractures. Key words: patellar fracture, osteosynhesis, surgical treatment Conflict of interest: the authors state no conflict of interest Funding: the study was performed with no external funding

A prospective study of 50 cases of patella fractures treated with different modalities

<p class="abstract"><strong>Background:</strong> Fractures of patella account for 1% of all skeletal injuries. There is no universal accepted treatment for patellar fractures. After a fracture of the patella, the best results are obtained by accurate reduction and stable internal fixation. Partial or total patellectomy is generally indicated when the patella is so severely comminuted that an accurate reduction and reconstruction of the retropatellar joint surface cannot be achieved.</p><p class="abstract"><strong>Methods:</strong> The prospective study of 50 cases of patellar fractures was carried out at the department of orthopaedics for the period from May 2015 to December 2017. The maximum period of follow up was 18 months with a minimum period of follow up of 5 months (average 11.68 months). Operative treatment was done in patella fractures for more than 2 mm of articular displacement or 3 mm of fragment separation. Surgical options includes internal fixation with tension band wiring with k wire and partial patellectomy with extensor mechanism repair.<strong></strong></p><p class="abstract"><strong>Results:</strong> We have studied 50 patients where 7 cases were treated conservatively. In the present series 22 patients were treated with internal fixation out of which 13 patients had excellent results. 6 patients had good results. 21 patients were treated with partial patellectomy where 6 patients had excellent results, 11 patients had good and 4 patients had fair results.</p><p class="abstract"><strong>Conclusions:</strong> Patella should be preserved and Osteosynthesis whenever possible has better chance for excellent results. A good surgical technique, optimal operation room environment and judicious use of antibiotics will reduce the possibility of infection.</p>