PURPOSE

To introduce the concept of fracture reduction with positive medial cortical support and its clinical and radiological correlation in geriatric unstable pertrochanteric fractures.

METHODS

A retrospective analysis of 127 patients (32 men and 95 women, with mean age 78.7 years) with AO/OTA 31A2.2 and 2.3 hip fractures treated with cephalomedullary nail (PFNA-II or Gamma-3) between July 2010 and June 2013 was performed. They were classified into three groups according the grade of medial cortical support in postoperative fracture reduction (positive, neutral, and negative). The positive cortex support was defined that the medial cortex of the head-neck fragment displaced and located a little bit superomedially to the medial cortex of the shaft. If the neck cortex is located laterally to the shaft, it is negative with no cortical buttress, and if the two cortices contact smoothly, it is in neutral position. The demographic baseline, postoperative radiographic femoral neck-shaft angle and neck length, rehabilitation progress and functional recovery scores of each group were recorded and compared.

RESULTS

There were 89 cases (70 %) in positive, 26 in neutral, and 12 in negative support. No statistical differences were found between the three groups among patient age, sex ratio, prefracture score of activity of daily living, walking ability score, ASA physical risk score, number of medical comorbidities, osteoporosis Singh index, fracture reduction quality (Garden alignments), and the position of lag screw or helical blade in femoral head (TAD). In follow-up, patients in positive medial cortical support reduction group had the least loss in neck-shaft angle and neck length, and got ground-walking much earlier than negative reduction group, with good functional outcomes and less hip-thigh pain presence.

CONCLUSION

Fracture reduction with nonanatomic positive medial cortical support allows limited sliding of the head-neck fragment to contact with the femur shaft and achieve secondary stability, providing a good mechanical environment for fracture healing.

UNLABELLED

The occurrence of proximal humerus fractures will continue to rise with the increasing elderly population. Many patients with proximal humerus fractures have osteoporosis and have poor neuromuscular control mechanisms. This predisposes them to future falls and additional fractures. Patients continue to have shoulder problems as a result of the fracture for many years after the injury. Rehabilitation is central to addressing the problems caused by the fracture. The review of the literature on proximal humerus rehabilitation suggests that treatment must begin immediately if the harmful effects of immobilization are to be avoided. Electrotherapy or hydrotherapy does not enhance recovery and joint mobilization has limited evidence of its efficacy. In the United Kingdom most patients are immobilized routinely for 3 weeks or longer and are referred for physical therapy. The best available evidence for shoulder rehabilitation emphasizes using advice, exercise, and mobilization of limited joints to restore upper limb function. Placing controlled stresses throughout the fracture site at an early stage will optimize bone repair without increasing complication rates. This approach requires cooperation between the referring surgeon and therapist and will optimize the patient's shoulder function and maintain their functional independence.

LEVEL OF EVIDENCE

Diagnostic study, level II (systematic review of level II studies). See the Guidelines for Authors for a complete description of levels of evidence.

PURPOSE

This study establishes a quantitative anatomical-mechanical-clinical decision-making mapping relationship using the Digital Intelligence Orthopaedic Technology, systematically analyses the dynamic biomechanical characteristics of distal humerus fracture in the postoperative period, and establishes the quantitative correlation between optimal strategies of plate configuration and safety thresholds for joint activities, to provide the scientific basis for optimizing internal fixation schemes and quantifying postoperative rehabilitation strategies.

METHODS

Upper limb muscle modeling was carried out in AnyBody software, muscle force, and other data were exported for finite distance solving and dynamic mechanical conditions were exported as the database for dynamic loading. Coupling the musculoskeletal dynamics simulation with finite element calculation, the elbow flexion-extension angle-muscle force-inner fixation stress transfer chain was established by AnyBody-Abaqus joint modeling technique to quantify the dynamic thresholds of the interface fracture micromovement (IFM) under different activity angles. The effects of different plate configurations (parallel plate, posterior medial plate, posterior lateral plate) on fracture stability and early healing were analyzed.

RESULTS

In this study, we systematically evaluated the biomechanical pattern of internal fixation of distal humerus fracture as well as the postoperative safe activity window and elucidated the enhancement path of functional recovery of distal humerus fracture utilizing AnyBody musculoskeletal dynamics analysis. By means of AnyBody musculoskeletal dynamics analysis, the humerus stress migration path showed anatomical-dependent characteristics, with gradient transfer from the hawks' fossa to the distal lateral condyle in flexion. Parallel plates stabilized the IFM in the bone healing window (0.06-0.20 mm) at 0-80° of flexion, whereas vertical plates breached the critical threshold (0.48 mm) in the IFM at > 30° of flexion. This reveals the law of mechanical matching between plate configuration and rehabilitation. There was a clear angle-dependent relationship between flexion angle and inter-fracture gap fragment motion (IFM). The IFM values tended to increase with increasing flexion and extension angles. When using parallel plates, allowing 0-80° of elbow flexion ensures better conditions for fracture healing. When using vertical plates, especially posterior medial plates active elbow flexion should be limited to about 30°.

CONCLUSIONS

In this study, we quantified the mechanical effect of muscle contraction force on the stability of internal fixation of distal humerus C-type fracture and revealed the biomechanical law in the postoperative period; we established a simulation model of dynamic and static loading and proposed a 'safe activity window' for postoperative exercise, which confirms the high stiffness of the parallel steel plate and the control of the angle of early active activity (≤ 80° of flexion). Flexion of more than 30° in the case of vertical plates leads to shear micromotion overruns (> 0.48 mm).

© 2025. The Author(s).

Fractures of the olecranon are common injuries with no single accepted treatment. Numerous clinical factors and biomechanical studies guide the surgeon in determining a treatment plan. The goals of surgical management include anatomical reduction and stable fixation, which allow early range of motion of the elbow joint. Numerous fixation methods have been described and include screw fixation, cerclage wiring, modified tension-band wiring, and plate fixation. The surgical technique depends on a combination of patient factors, the fracture pattern, and the mechanical stability of the fixation construct. Postoperative rehabilitation includes early active range-of-motion exercises and follows clinical and radiographic healing. Complications are related to the fracture, choice of implant, and surgical technique.