2.1 Study design, sitting, and ethics

This cross-sectional study was conducted at the Orthopedic Clinic of Hamadan Besat Hospital, affiliated with Hamadan University of Medical Sciences, Hamadan Province, Iran, between 2017 and 2019. Patients with clinical indications for PTO were referred to the clinic for evaluation and treatment. Verbal and informed consent were obtained from all participants to assess their satisfaction before and after surgery. To ensure confidentiality, no identifying information was collected, and patients were assured that all data would be reported in aggregate form without revealing individual identities.

2.2 Eligibility criteria

Inclusion criteria for the study were patients undergoing OW-PTO during the study period, aged between 25 and 50 years, and those who returned for follow-up within three months after surgery. The exclusion criterion was failure of patients to return for follow-up in the third month post-surgery.

2.3 Surgery and follow-up

The samples were selected using a convenience sampling method and were consecutively collected over a 2-year period. Patients underwent PTO with and without an allograft. Patient follow-up in the third month post-surgery was part of the routine care and monitoring process. Postoperative evaluations, including assessment of bone healing and complications, were conducted by the patients’ treating physician.

2.4 Data collection

The data collection tool included a researcher-made checklist for determining the frequency of postoperative knee complications and radiological results (supplementary material), as well as the KSS Knee Surgeons Association score to assess patient satisfaction with osteotomy.

In this study, the mean satisfaction scores of patients were compared before and after surgery using the Knee Society Scoring (KSS) system.⁸ The KSS system has two subsets: the knee score (related to knee joint assessment) and the performance score (related to the patient's ability to walk and climb stairs). This scale has 200 points, with 100 points allocated to the knee score, comprising 50 points for pain, 25 points for range of motion, and 25 points for stability. 100 points related to patient performance, including 50 points for stair climbing and 50 points for walking distance. In the presence of contracture in the flexed position of the joint, delay in knee extension, and improper alignment of the knee axis, the knee score is deducted. Additionally, if assistive devices are used for walking, the performance score is also deducted.

2.5 Statistical analysis

Data were described using tables, charts, and measures of central tendency and dispersion. To compare patient satisfaction and functional scores based on the KSS questionnaire before and after the intervention, the paired t-test was used. To compare the KSS scores in OW-PTO with and without allograft, the student's t-test was used. To compare nonunion at the osteotomy site and other complications based on qualitative nominal variables, Fisher's exact test was employed. A significance level of less than 0.05 was considered for this study.

3.1 Patients’ characteristics

This study included 55 patients who underwent OW-PTO. Of these, 39 (70.9 %) received allografts and 16 (29.1 %) did not. The mean age was 34.66 ± 9.15 years in the allograft group and 38.68 ± 7.49 years in the non-allograft group, with no statistically significant difference (p = 0.76). The cohort comprised 28 males (50.9 %) and 27 females (49.1 %), with no significant sex-based difference (p = 0.126) (Table 1).

3.2 Comparison of the patient satisfaction

Patient satisfaction scores significantly improved after OW-PTO in both groups. In the allograft group, the mean score increased from 76.53 ± 6.30 to 95.9 ± 6.67 (p < 0.001), while in the non-allograft group, it rose from 78.5 ± 5.00 to 96.88 ± 6.02 (p < 0.001) (Table 2). However, there was no statistically significant difference in satisfaction scores between the groups either before surgery (p = 0.217) or after surgery (p = 0.614), indicating comparable outcomes regardless of allograft use (Table 3).

3.3 Outcomes of OW-PTO with and without allograft

At three months postoperatively, tibial union was achieved in 94.9 % of patients in the allograft group and 87.5 % in the non-allograft group, with no statistically significant difference between the groups (p = 0.571). Similarly, complications occurred in 94.9 % of patients with allografts and 87.5 % without, with no significant difference noted (p = 0.571) (Table 4).

4.1 Study overview and key findings

This study aimed to evaluate the impact of allograft use on patient satisfaction and early clinical outcomes following proximal tibial OWHTO. By comparing two patient groups, those receiving an allograft and those who did not, we found that both cohorts demonstrated significant improvements in KSS postoperatively. However, there were no statistically significant differences between the groups in terms of patient satisfaction, bone union at three months, or complication rates. These findings suggest that allograft augmentation does not confer additional clinical benefit in the short term and that satisfactory outcomes can be achieved without its use.

4.2 Comparison with existing literature

Our results align with prior investigations evaluating the effectiveness of OW-PTO both with and without bone graft materials. A case-control study involving 123 patients undergoing OW-PTO reported an 88.6 % satisfaction rate after at least two years, with key predictors of positive outcomes including postoperative pain relief, restoration of function, and fulfillment of surgical expectations.⁹ These results align with our findings, highlighting that perceived success often depends on factors beyond graft usage, such as pain control and realistic preoperative counseling.

Ihle et al.¹⁰ prospectively assessed 120 patients undergoing OW-PTO without bone grafting and demonstrated significant improvements in physical health-related quality of life (HRQL) and functional scores over an 18-month period. While lower preoperative mental health scores were associated with delayed recovery and poorer early outcomes, most patients returned to near-normal mental HRQL by six months. Our study, though shorter in follow-up duration, similarly showed favorable early results regardless of graft use.

Corbeil et al.¹¹ retrospectively evaluated 175 OW-PTO procedures and confirmed that favorable clinical outcomes, including high KOOS scores and the absence of nonunion, were achievable without grafting. Poorer outcomes were more often related to modifiable risk factors such as high body mass index, limited preoperative knee flexion, and smoking. These observations support the view that patient selection and risk mitigation strategies may be more influential on outcomes than graft material alone.

From an economic perspective, Ferrer-Rivero et al.¹² compared open- and closing-wedge PTO and found that although both techniques provided comparable functional outcomes, the closing-wedge approach was more cost-effective. Although our study did not conduct a formal cost analysis, the exclusion of allografts inherently reduces procedure-related expenses, aligning with the principle of value-based surgical care.

Jabalameli et al.¹³ studied autologous bone grafting in a cohort of 29 patients and reported no cases of nonunion or malunion, although complications such as superficial infections and intra-articular fractures were observed. Our study builds on this work by incorporating a larger sample size and directly comparing outcomes with and without grafts, thereby providing more generalizable evidence.

Additionally, a systematic review and meta-analysis evaluating graft use in OW-PTO found no significant differences in alignment correction, complication rates, or clinical outcomes between autograft, allograft, and no-graft techniques.⁷ Interestingly, OW-PTO without grafting was associated with better knee function scores, and allograft use helped avoid donor site morbidity and shortened operative times. These data support the notion that graft choice, or omission, should be tailored to individual patient characteristics rather than universally applied.

Furthermore, long-term outcomes from studies using artificial substitutes and rigid fixation have demonstrated sustained functional improvement and mechanical alignment up to a decade postoperatively, even in older patients.¹⁴ This reinforces the procedure's durability, and our findings suggest that short-term success is achievable without grafting, provided that mechanical stability is ensured during the fixation process.

4.3 Clinical implications

Our findings have several important implications for clinical practice. First, the absence of significant differences in satisfaction, union rates, and complications between the grafted and non-grafted groups supports a selective approach to graft use. In patients with good bone quality and adequate fixation, the omission of allograft material does not appear to compromise early outcomes. This is particularly relevant in low-resource environments where graft materials may be limited or costly. Avoiding unnecessary allograft use can reduce surgical time, lower costs, and eliminate risks associated with graft sourcing, storage, and potential immunogenic response. From a pragmatic standpoint, surgeons should consider reserving grafts for complex cases, such as large corrections or poor bone quality, where structural support may be critical.

4.4 Study strengths and limitations

A key strength of this study lies in its practical applicability in real-world settings. The inclusion of patients from a routine clinical setting enhances generalizability, and the use of a validated outcome measure (KSS) ensures objective assessment of both functional and satisfaction parameters. However, several limitations must be acknowledged. The study's retrospective design and relatively small sample size may limit statistical power and increase the risk of type II error. The three-month follow-up period is sufficient for assessing early healing and patient satisfaction, but does not capture long-term outcomes, such as progression to osteoarthritis or complications related to the hardware. The lack of randomization and potential selection bias, due to convenience sampling, further limits causal inference. Additionally, the subjective nature of satisfaction assessments may have been influenced by a lack of blinding.

4.5 Future research directions

To strengthen the evidence base, future investigations should focus on prospective randomized controlled trials comparing OW-PTO with and without grafts across larger, demographically diverse populations. Long-term follow-up is crucial for evaluating the impact of graft use on maintaining alignment, preserving joints, and preventing progression to arthroplasty. Integrating cost-effectiveness analyses, patient-reported outcomes, and imaging biomarkers would also enhance the clinical utility of future studies. Moreover, subgroup analyses could help identify patient profiles most likely to benefit from graft augmentation.