Letter to the Editor: Anterior knee pain after anterior cruciate ligament reconstruction with bone-patellar tendon-bone graft: Inevitable or avoidable with autologous bone grafting?

Abstract

Anterior knee pain remains one of the most persistent drawbacks of anterior cruciate ligament reconstruction using bone-patellar tendon-bone (BPTB) autografts. Traditionally viewed as an unavoidable consequence of graft harvest, anterior knee pain has led many surgeons to favor alternative graft choices despite the superior biomechanical properties of BPTB. The study published in the World Journal of Orthopedics by Byravamoni Venugopal et al challenges this paradigm by demonstrating that autologous bone grafting of the patellar and tibial donor site defects - using cancellous bone collected during tunnel drilling - can markedly reduce postoperative pain and morbidity. Their findings, showing 95.8% of patients pain-free at one year, suggest that donor site management rather than graft type may be the key determinant of postoperative comfort. While further prospective studies are needed to confirm these results, this technique represents a promising, biologically sound, and cost-effective strategy to mitigate one of the most common complications following BPTB reconstruction.

Key Words: Anterior knee pain; Bone-patellar tendon-bone; Autologous grafts; Anterior cruciate ligament reconstruction; Donor site morbidity

Core Tip: This study challenges the long-held belief that anterior knee pain is an inevitable consequence of anterior cruciate ligament reconstruction using bone-patellar tendon-bone grafts. By employing autologous bone grafting to fill donor site defects, the researchers demonstrate a significant reduction in postoperative anterior knee pain, with 95.8% of patients pain-free at one year. This innovative approach not only emphasizes the importance of effective donor site management but also presents a cost-effective, biologically sound strategy that could enhance patient outcomes and redefine surgical practices in anterior cruciate ligament reconstruction.

TO THE EDITOR

Anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone (BPTB) autograft remains one of the most time-tested procedures in orthopedic surgery. Its advantages - bone-to-bone healing, high initial fixation strength, and excellent long-term stability - have positioned it as the “gold standard” for young, active individuals. However, the well-documented donor site morbidity, particularly anterior knee pain (AKP), continues to overshadow its biomechanical superiority. AKP is characterized by persistent, diffuse discomfort localized to the peripatellar or retropatellar regions. Its etiology in the context of BPTB grafts is multifactorial, involving potential causative factors such as surgical trauma at the harvest site, injury to the infrapatellar branch of the saphenous nerve, and altered patellofemoral joint mechanics post-reconstruction[1]. For decades, surgeons have reluctantly accepted AKP as an almost inevitable trade-off for graft stability.

The study by Byravamoni Venugopal et al[2] published in the recent issue of the World Journal of Orthopedics challenges this long-held assumption with a biologically simple yet clinically effective solution. Through a retrospective study, the authors evaluate the incidence and severity of AKP following the systematic application of autologous bone grafting - using bone harvested during the procedure itself - to fill the patellar and tibial donor site defects. Their results demonstrate a remarkably low incidence of clinically significant AKP (4.2%) and excellent short-term functional outcomes. This suggests that the technique, which is simple, reproducible, and cost-effective, could be routinely integrated into surgical practice to minimize donor site morbidity. The study underscores the importance of optimizing functional outcomes and patient satisfaction in ACL reconstruction, providing relevant evidence for the ongoing discussion on the standardization of surgical techniques in orthopedics.

UNDERSTANDING THE RATIONALE

The etiology of AKP following ACL reconstruction with BPTB graft is multifactorial[3]. Key contributing factors include donor site morbidity, untreated bony defects, nerve injury, and postoperative biomechanical changes. Donor site morbidity is particularly significant, as residual bony defects in the patella or tibia can exacerbate pain if not adequately addressed during surgery. Bone grafting of the patellar defect is crucial; it has been shown to reduce both the prevalence and severity of AKP, including kneeling discomfort and loss of extension, in comparison to leaving the defect untreated[4,5]. Restoring the defect with bone graft may also decrease the risk of patellar fracture by eliminating the stress riser at the harvest site[1].

Additionally, the pathophysiology of AKP following BPTB graft harvest involves infrapatellar nerve injury, scar formation, periosteal stripping, and mechanical stress due to unhealed bony defects[6]. Unfilled donor site voids can serve as focal points for stress concentration, thus perpetuating discomfort. Grafting these defects with the patient’s own cancellous bone, obtained during routine tunnel drilling, reintroduces biological continuity at the harvest sites, promoting early bone healing and reducing the stress risers that contribute to AKP. This technique exemplifies biological economy - utilizing the material produced during the operation without incurring additional costs, incisions, or synthetic substitutes - reflecting a return to fundamental surgical principles of respecting tissue biology, self-sufficiency, and simplicity.

WHERE THIS STUDY FITS IN THE LITERATURE

Various causes of AKP following BPTB ACL reconstruction have been extensively discussed in the literature over the years. A systematic review published by Frank et al[7] in 2015 found no statistically or clinically significant differences between closing or not closing the patellar tendon defect after ACL reconstruction with BPTB autograft, indicating the need for further rigorous research. In recent years, attention has shifted to the patellar bone defect as a principal contributor to AKP. Lameire et al[4] published a systematic review highlighting that AKP rates are significantly lower in patients receiving bone grafting for the patellar defect, with prevalence ranging from 22%-57% in the non-grafted group compared to only 10% in the grafted group. Since as early as 1990, authors such as Daluga et al[8] and Ferrari and Bach[9] have proposed utilizing bone shavings obtained during the drilling of tibial and femoral tunnels, along with bone fragments from notchplasty or bone block osteoplasty, to fill the patellar defect. This effective technique optimizes available bone volume and has been shown to decrease donor site morbidity, minimizing AKP and reducing the risk of patellar fracture. The graft is precisely placed into the defect and covered with the peritenon, aiding in bone integration and facilitating functional recovery[8,9].

On the other hand, a recent study by Martorell-de Fortuny et al[10] challenges previous findings, demonstrating that filling the patellar bone defect with autologous bone after BPTB ACL reconstruction does not significantly reduce AKP or improve functional outcomes. In this randomized controlled study, patients with filled patellar defects exhibited greater bone regeneration on magnetic resonance imaging at one year but showed no significant differences in pain or functional scores compared to those whose defects remained unfilled[10].

While earlier reports have investigated bone grafting of donor sites, few have assessed the outcomes of simultaneously grafting both patellar and tibial defects. Early studies, such as those by Brandsson et al[11] demonstrated limited benefits from only filling the patellar defect. More recent work by Shichman et al[5] and Krishna et al[12] supports the practicality of autologous bone use in this context. Byravamoni Venugopal et al[2] build upon this foundation by systematically applying the method and reporting clinical outcomes that rival or exceed those of prior studies. Their findings align with the broader movement toward sustainable orthopedic practices, leveraging intraoperative biological resources to enhance healing and reduce morbidity.

CRITIQUE AND FUTURE DIRECTIONS

Despite its strengths, the study’s limitations must be acknowledged. It is a retrospective, single-center study with a modest sample size and lacks a control group for direct comparison. Furthermore, the twelve-month follow-up period, while capturing early morbidity, is insufficient to evaluate long-term clinical outcomes such as kneeling tolerance or the degree of radiographic remodeling.

A critical technical consideration is that this procedure relies on autologous bone harvested specifically from the tibial and femoral tunnels. However, it remains to be determined whether the volume of bone retrieved from these tunnels is consistently sufficient to achieve an optimal fill of the patellar defect. Should this local supply prove inadequate, clinicians might need to consider supplementary bone from other donor sites, which further underscores the necessity of contextualizing these findings.

As the literature indicates, pain profiles and complication rates vary significantly depending on the specific donor site and the harvest technique employed[13]. Even in preclinical models, the biological and mechanical responses to bone harvesting are site-specific, factors that can directly influence postoperative patient discomfort[14]. Therefore, deepening the analysis to compare the morbidity of this technique with other autologous transplant procedures is essential for a comprehensive understanding of its clinical utility.

Nonetheless, these findings establish a compelling proof of concept. Future prospective, randomized trials comparing standard BPTB harvest with and without autologous grafting - incorporating comparative pain assessments against other common autograft donor sites - are warranted. Long-term imaging and patient-reported outcomes will be vital to validate whether this technique should become a routine adjunct in ACL reconstruction.

Moreover, it should be noted that the surgical technique employed for graft harvesting plays a crucial role in postoperative pain and donor site morbidity. Factors such as the type of incision, preservation of neural structures, management of bone defects, and minimization of soft tissue trauma can significantly influence patient outcomes. Optimizing these technical aspects may help reduce the incidence and severity of donor site pain, further enhancing the clinical utility of the procedure[15].

CLINICAL IMPLICATIONS

This work compels surgeons to reconsider what has long been accepted as unavoidable. If such a simple maneuver - recycling autologous bone to fill donor-site voids - can nearly eliminate postoperative AKP, then the BPTB graft may reclaim its position as the most balanced option between biomechanical stability and patient comfort. In an era where cost-effectiveness and biologic respect are paramount, this technique embodies both.

CONCLUSION

Byravamoni Venugopal et al[2] remind us that innovation need not always come from technology - it can arise from a renewed understanding of biological fundamentals. Their results suggest that AKP after BPTB ACL reconstruction is not inevitable but, indeed, avoidable. By harnessing the healing potential of the patient’s own bone, this approach closes both the physical and conceptual gaps in ACL reconstruction. Sometimes, the simplest solutions are the most profound.