Iranian Journal of Orthopedic Surgery

Abstract Total Hip Arthroplasty (THA) and prosthetic joint replacement are among the most successful orthopedic surgeries of the modern era. The most critical challenge in this field lies in the bearing surfaces of prostheses, which are closely linked to implant survivorship and longevity. Since the development of the first successful prosthesis, significant advancements have been made in enhancing strength and reducing brittleness and wear of these surfaces, as wear-induced osteolysis leads to prosthetic failure. A hip prosthesis consists of several components, but this study focuses on the applications and properties of polyethylene in the acetabular cup, particularly its various types, including ultra-high-molecular-weight polyethylene (UHMWPE), cross-linked polyethylene (XLPE), and vitamin E-infused polyethylene (VEPE). The study aims to analyze the mechanical, chemical, and biological properties of these materials and compare them with conventional alternatives such as metals and ceramics. The research method involved a comprehensive review of clinical studies, laboratory experiments, and research reports on polyethylene’s performance in acetabular components. Findings indicate that modern polyethylene materials, such as HXLPE (highly cross-linked polyethylene) and VEPE, significantly improve implant longevity while reducing complications like particle generation and wear. Compared to other materials, polyethylene offers advantages in cost-effectiveness and biocompatibility, though it still has limitations in mechanical strength when compared to ceramics and metals. This study highlights key recommendations for improving wear resistance, exploring novel composite materials, and minimizing the environmental impact of polyethylene production and usage. The findings provide valuable insights for future research and the development of more advanced prosthetic implants.

Abstract Background: Polymethyl methacrylate (PMMA), is a well known biocompatible polymer widely used in the preparation of bone cements. The size and morphology of cement powder phase play important role in physical and mechanical properties of the resultant cement. This study aimed to evaluate the structure, mechanical strength and cytocompatibility of bone cements made of the same liquid phase and powders with different morphologies.
Methods: PMMA microspheres were synthesized via an oil-in-water emulsion solvent evaporation method, and the effect of particle size on the structure, mechanical properties and cytotoxicity of acrylic-based bone cements was investigated. Two different concentrations of the organic PMMA solution (5 and 20 wt%) were employed to control the particle size. XRD and FTIR techniques were employed to characterize phase and chemical bands. The setting time, compressive strength and cell viability were assessed by standard procedures.
Results: XRD and FTIR analyses confirmed the structural purity and complete removal of undesired phases, while SEM images revealed uniform spherical particles. The results showed that decreasing the average particle size from approximately 200 to 20 µm reduced the cement setting time from 300 to 90 seconds and increased the compressive strength from 21.4 to 81.7 MPa. Cements made of both different-sized powders exhibited adequate cell viability.
Conclusion: The findings indicate that controlling the size of PMMA microparticles can play an effective role in developing bone cements with optimized strength and setting time for medical and dental applications. These results provide valuable insights to improve the clinical performance of acrylic bone cements.

Abstract Background and Aim:
Total knee arthroplasty (TKA) is a standard treatment for advanced osteoarthritis. Mechanical alignment has long been the conventional approach, while kinematic alignment has been introduced to restore the native joint axis. This study aimed to compare functional outcomes of TKA performed with mechanical and kinematic alignment.

Materials and Methods:
This retrospective cohort study was conducted in 2024 at Mehregan and Arjomand Hospitals in Kerman, Iran. The study population included patients who underwent TKA between 2018 and 2023 using either mechanical or kinematic alignment performed by two knee specialists. Patient data were extracted from medical records, and functional outcomes were assessed using the Lysholm questionnaire. Statistical analyses were performed using SPSS version 23.

Results:
Two hundred patients were evaluated (100 in each group). In the kinematic group, 69% were female and 31% male, while in the mechanical group, 74% were female and 26% male. The mean age was 68.02 years in the kinematic group and 69.61 years in the mechanical group. The mean follow‑up duration was 51.37 months in the kinematic group and 53.41 months in the mechanical group. No significant differences were observed between groups regarding demographics. The mean Lysholm score was slightly higher in the kinematic group (85.18) compared to the mechanical group (84.40), but the difference was not statistically significant (p = 0.62). Subscale scores, including limping, walking aids, pain, instability, swelling, and squatting, showed no significant differences.

Conclusion:

Abstract Abstract
Background: Unstable proximal femoral fractures are among the most common causes of mortality and disability in the elderly, with an increasing incidence due to rising life expectancy. To date, no comprehensive guideline exists for the surgical management of these fractures, and non-surgical approaches are generally associated with higher complication rates.
Methods: In this retrospective descriptive study, 23 patients (12 males and 11 females) with unstable proximal femoral fractures (AO/OTA 31-A2 and 31-A3) who underwent fixation with a dynamic condylar screw (DCS) between 2019 and 2023 at 5 Azar Hospital, Gorgan, were evaluated. Data were collected from electronic medical records and through in-person/telephone follow-up visits for one year post-surgery. Outcomes were assessed using the Harris Hip Score (HHS), time to radiographic union, and mechanical/non-mechanical complications.
Results: The mean age of patients was 68.5 years. The mean Harris Hip Score was 74.9 ± 8.5, and the mean time to union was 14.9 ± 2.2 weeks. Mechanical complications occurred in 21.7% of patients (most common: lag screw cut-out), and non-mechanical complications were observed in 47.8% (most common: need for blood transfusion). Female gender and older age were associated with higher complication rates and delayed union, although these associations were not statistically significant.
Conclusion: The dynamic condylar screw is an effective method with acceptable functional outcomes in unstable proximal femoral fractures. However, larger studies with control groups are required to confirm these findings.

Abstract Abstract

Purpose: Subscapularis (SSC) tendon tears significantly impact shoulder stability and function. While conventional MRI serves as the preferred noninvasive diagnostictool, its accuracy shows considerable variation across different populations. This study aimed to comprehensively evaluate the diagnostic accuracy of conventional 1.5-Tesla MRI for detecting SSC tears in a distinct Iranian population, using arthroscopy as the gold standard, and to identify key demographic and technical factors influencing its diagnostic performance through multivariate analysis.

Methods: A multicenter cross-sectional study was conducted across three university hospitals from 2023 to 2025. We enrolled 185 patients scheduled for shoulder arthroscopy who had undergone preoperative conventional 1.5-Tesla MRI following a standardized imaging protocol. MRI interpretations were independently evaluated by two musculoskeletal radiologists and one orthopedic shoulder surgeon, all blinded to clinical data. Arthroscopic findings served as the reference standard. We calculated sensitivity, specificity, positive and negative predictive values, and performed multivariatelogistic regression.

Results: For detecting any SSC tear, conventional MRI demonstrated an overall sensitivity of 52.3% and specificity of 85.4% across all readers. Diagnostic accuracy wassignificantly superior in older patients (>65 years) and when the dominant arm was affected. Multivariate analysis confirmed that patient age, limb dominance, and specific MRI sequence parameters independently influenced diagnostic performance.

Conclusion: Conventional MRI shows moderate sensitivity but high specificity for SSC tendon tears. Its diagnostic performance is significantly affected by specific patient factors and imaging parameters. These important findings highlight the clinical necessity for optimized imaging protocols and alternative diagnostic approaches when strong clinical suspicion persists despite negative MRI results.

Abstract Background:
Accurate implant sizing is crucial for optimal outcomes in total knee arthroplasty (TKA). Traditional preoperative templating methods are time-intensive and dependent on imaging. This study aimed to evaluate the relationship between shoe size and femoral and tibial component dimensions to determine whether shoe size can reliably predict implant sizing and postoperative pain intensity.

Material Methods:
A prospective cross-sectional study was conducted on 100 patients (50 men, 50 women) undergoing primary unilateral TKA. Preoperative shoe size was measured using a standardized protocol, and intraoperative femoral and tibial component sizes were recorded. Linear regression analysis assessed the correlation between shoe size and implant dimensions, while postoperative pain was measured using a 10-point visual analog scale (VAS) at 24 hours.

Results:
Shoe size was a significant predictor of both femoral (R² = 0.583, p < 0.001) and tibial (R² = 0.572, p < 0.001) component sizes. Prediction accuracy within ±1 implant size was 96% for femoral and 93% for tibial components. No significant correlation was found between shoe size, implant dimensions, and postoperative pain (p > 0.1).

Conclusion:
Shoe size serves as a reliable, radiation-free anthropometric predictor for femoral and tibial component sizing in TKA, with predictive accuracy comparable to digital templating methods. This simple, cost-effective approach may improve preoperative planning efficiency and resource utilization, especially in resource-limited settings. Further multicenter studies are recommended to validate these findings across diverse populations and implant systems.

Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Abstract Introduction: Capitellar fractures are uncommon intra-articular injuries often misdiagnosed initially. Neglected cases typically progress to malunion, causing substantial elbow stiffness, persistent pain, and functional impairment. This series details three patients with neglected Type 2 capitellar malunions, demonstrating surgical intervention via the Kaplan approach effectively restores elbow motion, alleviates pain, and enables return to daily activities.
Case Presentation: Three patients (two females, one male) aged 25-34 years presented with elbow stiffness and chronic pain months after initial trauma. All had untreated or misdiagnosed fractures. CT imaging confirmed Type 2 capitellar malunion in all cases. Surgical management through the Kaplan approach provided excellent visualization for anatomical reduction. Stable fixation was achieved using headless or compression screws based on fracture characteristics.
Clinical Discussion: The surgical approach enabled early postoperative mobilization. All patients initiated active range-of-motion exercises within the first week. This rehabilitation protocol prevented recurrent stiffness and promoted optimal recovery. At final follow-up, all patients that achieved near-complete functional elbow motion. All participants returned to pre-injury activity levels without residual pain or functional limitations. Follow-up evaluations confirmed a maintained recovery without complications.
Conclusion: Neglected Type 2 capitellar fractures present considerable therapeutic challenges, typically culminating in painful malunion and severe elbow dysfunction. However, this case series conclusively demonstrates that timely and precise surgical intervention utilizing the Kaplan approach for anatomical reduction and stable internal fixation, when integrated with a structured and aggressive early rehabilitation program, can yield excellent functional restoration and highly satisfactory patient-reported outcomes, establishing it as a reliable and effective treatment strategy.

Abstract Complex Regional Pain Syndrome (CRPS) after knee and hip arthroplasty is a rare but clinically significant condition characterized by disproportionate pain, vasomotor/sudomotor disturbances, and motor–trophic changes. This narrative review, with a focus on arthroplasty patients, summarizes the latest evidence on definition and classification (Budapest criteria and Valencia adaptation), epidemiology and risk factors, the place of CRPS within the “painful prosthesis” algorithm, and conservative, pharmacological, and advanced treatment options. Prospective data indicate that strict application of the Budapest criteria reduces overdiagnosis and confirms that CRPS is uncommon after total knee arthroplasty, although higher preoperative pain intensity and extent may increase risk. In hip arthroplasty, the evidence is limited mainly to case reports and small case series. Within diagnostic work-up, stepwise exclusion of prosthetic joint infection, mechanical assessment with radiography/CT, and targeted use of SPECT/CT (particularly in the knee) are essential before considering CRPS, while nuclear imaging is not specific for “confirming” CRPS. From a therapeutic standpoint, the cornerstone of effective management is early, multidisciplinary rehabilitation combined with multimodal analgesia. Randomized trials provide strong evidence for bisphosphonates, moderate benefit for short-course corticosteroids in the early inflammatory phase, limited adjunctive effects for gabapentinoids, and inconsistent findings regarding vitamin C. In refractory cases, sympathetic blocks, subanesthetic ketamine infusions (short-term effect), and neuromodulation—especially dorsal root ganglion stimulation for focal limb pain—may be useful. The review concludes by proposing a stepwise care pathway and highlighting research priorities, particularly the need for standardized outcome measures.