Patellar giant cell tumour treated with extended curettage, bone grafting and extensor mechanism augmentation: a case report

INTRODUCTION

Primary tumours of the patella are uncommon, and most reported lesions are benign or intermediate. In larger radiologic and clinicopathologic series, giant cell tumor of bone (GCTB) is an important diagnosis in skeletally mature patients presenting with persistent anterior knee pain.^1-3 GCTB is histologically benign but locally aggressive and carries a risk of recurrence, making meticulous intralesional technique central to successful joint-preserving management.^4-7 Patellar GCTB presents additional reconstructive challenges because the patella has limited bone stock, and extensor mechanism integrity is paramount for functional recovery. We report a young man with progressive patellar GCTB treated with extended curettage and iliac crest grafting combined with extensor mechanism augmentation using hamstring autograft and suture tape reinforcement, with a durable outcome at five years.

CASE REPORT

A 21-year-old male presented with a six-month history of progressive left anterior knee pain. The pain was present even at rest and increased with activity, particularly stair climbing, squatting, and running, and had started to limit his daily function. He first reported to our outpatient service in early 2020, shortly before the onset of widespread COVID-19-related restrictions. Initial radiographs demonstrated an expansile lytic lesion involving the left patella (Figure 1 A and B), and MRI confirmed an intraosseous patellar lesion with features suggestive of an aggressive benign tumour, without any obvious distant disease. Based on the clinicoradiologic picture, a patellar bone tumour was suspected, and definitive surgical management was planned.

Due to pandemic-related restrictions, the planned procedure was delayed by approximately three months. When he returned for review, the patient reported worsening pain and increased functional limitation compared with the initial visit. Repeat radiological evaluation suggested interval progression of the lesion (Figure 2 A and B), and in view of the anticipated larger defect after tumour excision and the risk to extensor mechanism function, the surgical plan was revised to combine joint-preserving tumour surgery with extensor mechanism protection.

The patient underwent surgery under regional anaesthesia through an anterior approach to the patella. An extended intralesional excision was performed using thorough curettage with high-speed burring. The post-curettage defect (Figure 3 A) was reconstructed using autologous cancellous iliac crest bone graft. Given concern regarding vulnerability of the patellar tendon attachment and extensor mechanism integrity after excision and reconstruction, patellar tendon augmentation was performed using ipsilateral hamstring autograft combined with suture tape reinforcement (FiberTape), which was secured to the tibia through a transverse osseous tunnel to provide a load-sharing construct during healing and rehabilitation (Figure 3 B). Histopathological examination confirmed a GCTB (Figure 4).

Postoperatively, a protected rehabilitation program was followed, with gradual progression of knee motion and strengthening. The patient recovered rapidly and achieved excellent functional restoration with a Kujala score of 92/100 and Tegner Lysholm knee score of 93/100 at one year. He demonstrated painless straight-leg raise, comfortable squatting, and return to walking and running without limitation. At final follow-up of 5 years active knee extension was symmetric compared with contralateral side, with no extensor lag and also no difficulty in squatting and cross-leg sitting (Figure 5). He remained pain-free (VAS 0) with sustained excellent function, as evidenced by a Kujala score of 100/100 and a Tegner Lysholm knee score of 100/100. And there was no evidence of local recurrence on follow-up imaging (Figure 5 A and B).

DISCUSSION

GCTB of the patella is uncommon yet clinically important because limited patellar bone stock and involvement of the tendon footprint can quickly translate into extensor mechanism dysfunction. In the classic radiologic series by Kransdorf et al patellar tumours were heterogeneous and imaging alone could not reliably distinguish benign from malignant lesions; notably, despite older impressions that GCTB is the commonest benign patellar tumour, their 42-case series found chondroblastoma to be most frequent among benign neoplasms, underscoring the need for a broad differential and histologic confirmation.¹ In contrast, Song et al emphasised that most patellar tumours are benign overall and that GCTB remains a recurring adult patellar diagnosis, supporting its relevance in young adults with persistent anterior knee pain.³ Ferguson et al similarly highlighted the rarity and diagnostic heterogeneity of patellar tumors, reinforcing the importance of careful clinicoradiologic assessment and timely definitive management.²

Biologically, GCTB is benign but locally aggressive, and recurrence risk is closely linked to the adequacy of intralesional excision and local control measures. Campanacci et al provided the foundational clinicopathologic framework for GCTB behaviour and grading.⁴ Contemporary reviews such as Sobti et al reaffirm that joint-preserving surgery is appropriate for many extremity lesions when aggressive intralesional technique is applied.⁵ In line with this, Gundavda and Agarwal emphasise that extended curettage, adequate exposure, meticulous curettage, and high-speed burring remain a workhorse for local control.⁶ Our management followed these principles with extended curettage and biological reconstruction, while also addressing extensor mechanism vulnerability, which is a distinctive challenge in patellar lesions.

Reconstruction after curettage is debated and depends on site-specific biomechanics. In the Scandinavian Sarcoma Group cohort, Kivioja et al recommended cementation in intralesional surgery for many GCTB lesions, citing immediate structural support and potential facilitation of recurrence detection, with a median five-year follow-up.⁷ Nonetheless, recurrence remains possible even with modern techniques; Gouin et al reported recurrence after curettage in appendicular lesions, reinforcing the need for recurrence surveillance as a key outcome.⁸ Adjuvant strategies also vary: van der Heijden et al compared liquid nitrogen and phenolization across two centres, highlighting how adjuvant choice is shaped by institutional practice and lesion characteristics.⁹ In the patella, reconstruction decisions must additionally account for limited bone volume, patellofemoral stresses, and the tendon attachment; in the current patient, autologous iliac crest grafting was chosen to restore bone stock and complement planned extensor protection.

Positioning present case within prior reports is instructive (Table 1). Slavchev et al described an “active” patellar GCTB that was successfully treated with curettage and grafting, supporting patellar preservation when anatomy permits.¹⁰ At other extreme, Malhotra et al reported an aggressive patellar GCTB with patellar tendon involvement, requiring wide resection and allograft reconstruction of patella, patellar tendon, and tibial tubercle, illustrating that extensive patella-tendon compromise may necessitate radical reconstruction.¹¹

Current case lies between these extremes: despite interval clinical progression and increasing functional limitation, patellar preservation remained feasible, but we differentiated management by adding deliberate augmentation of extensor mechanism.

The rationale for augmentation is supported by patellar tendon repair biomechanics. Although not tumour-specific, the mechanical goal of protecting a tendon-bone interface and limiting gap formation during early healing is analogous. Gould et al demonstrated improved cyclic gap formation with high-strength suture tape augmentation in a transosseous patellar tendon repair model, supporting the “internal brace” concept.¹⁷ Rothfeld et al similarly showed biomechanical benefits with internal brace augmentation.¹⁸ We applied these load-sharing principles by augmenting the extensor mechanism with a hamstring graft and FiberTape through a transverse tibial tunnel, which aligned with the clinical outcome: excellent recovery within one year and durable 5-year function without recurrence.

The early-2020 service disruption provides relevant context. Fitzgerald et al documented morbidity associated with COVID-19-related delays in orthopaedic oncology, supporting the pragmatic need to reassess patients after postponement and revise surgical planning when functional structures may be at risk.¹⁹ Overall, this case suggests that combining oncologic intralesional principles with proactive extensor mechanism reinforcement can be a reproducible option in selected patellar GCTB cases.^10,11,18,19

CONCLUSION

Patellar giant cell tumor of bone is uncommon and functionally important because preservation of knee extension strength is central to outcome. This report demonstrates that patellar preservation using extended curettage and iliac crest bone grafting, combined with hamstring autograft and suture tape reinforcement through a transverse tibial tunnel, can result in excellent and durable function maintained at five years. This augmentation strategy may be considered when extensor mechanism integrity is threatened after joint-preserving patellar tumor surgery.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: Not required

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