Nonsyndromic Osteochondroma of Lumbar Spine: A Systematic Review of Management and Outcomes with Illustrative Case

Keywords

OC - spinal neoplasms - case reports - lumbar vertebrae - review

Introduction

Osteochondromas (OCs), or osteocartilaginous exostoses, are the most common benign bone tumors. As described by Dahlin and Unni, OCs make up approximately 8.5% of all bone tumors and 36% of benign bone tumors.[1] OCs usually appear as solitary lesions or as part of multiple hereditary exostoses (MHE), an autosomal dominant condition also called osteochondromatosis, Bessel-Hagel syndrome, or diaphyseal aclasis. Although solitary OCs (SOCs) are more common overall, several studies suggest that spinal OCs tend to occur more often as SOCs rather than with MHE.[2] [3] Additionally, an estimated 10 to 15% of OCs may develop as a delayed result of previous radiation exposure.[4]

OCs of the spine are rare, making up only approximately 1.3 to 4.1% of SOCs and roughly 0.4% of all intraspinal tumors.[1] [5] [6] The cervical vertebrae, especially C2, are most commonly affected, followed by C3 and C6.[7] Thoracic involvement accounts for approximately 28% of spinal OCs,[8] [9] while the lumbar spine is less frequently affected. The incidence of OCs decreases gradually farther down the spine. Despite their rarity, lumbar OCs are still clinically important because of their potential for neurological issues and unique management considerations.

It was once thought that lumbar OCs rarely led to neurological issues because they tend to grow outward from the canal.[10] [11] [12] [13] [14] [15] However, newer evidence suggests that lumbar OCs often grow into the canal and can cause radiculopathy. Earlier studies noted that lumbar OCs are frequently asymptomatic, but growing evidence shows that intracanalicular extension can result in notable neurological symptoms. Since this condition is rare and large-scale studies are limited, treatment approaches mainly depend on individual cases and small series.

This systematic review aims to compile existing literature to better understand the clinical presentation, management approaches, and outcomes of nonsyndromic lumbar spine OCs, complemented by a case from our institution.

Materials and Methods

Registration

The protocol for this systematic review was prospectively registered in the PROSPERO international prospective register of systematic reviews (registration number: CRD420251119471). All methods were developed in accordance with the registered protocol and followed established PRISMA 2020 guidelines.

Search Strategy

We conducted a systematic literature search following PRISMA guidelines in PubMed, Embase, Web of Science, and Scopus, from inception through April 2024. The search strategy included Medical Subject Headings and relevant keywords: (“OC” or “osteocartilaginous exostoses”) and (“lumbar spine”). No restrictions were imposed on study design or date. Only English-language articles and studies reporting nonsyndromic lumbar spine OCs were included.

Eligibility Criteria

Studies were eligible for inclusion if they reported clinical cases or series of nonsyndromic OCs located in the lumbar spine, provided sufficient detail on clinical presentation, tumor characteristics, management, and postoperative outcomes, and were published in English. Studies were excluded if they involved nonspinal lesions, hereditary exostosis syndromes, nonhuman subjects, infectious or inflammatory conditions, or were non-English articles. Title, abstract, and full-text screening were independently performed by two researchers, with any disagreements resolved through discussion or adjudication by a third reviewer.

Data Extraction Process and Extracted Data

Data extraction was performed independently by two researchers. For each included study, we collected data on patient demographics (age, sex), tumor characteristics (size, spinal level, location, extension), clinical presentation, operative management (surgical approach, instrumentation, extent of resection), and postoperative outcomes (clinical improvement, recurrence, complication rates, follow-up duration). Extracted data were cross-checked, and discrepancies were resolved by consensus or, if needed, with input from a third researcher.

Risk of Bias

The risk of bias for each included study was evaluated using the Joanna Briggs Institute (JBI) critical appraisal tools tailored for case reports and case series. Two reviewers independently assessed the methodological quality, focusing on aspects such as clarity of clinical history, diagnosis confirmation, follow-up adequacy, and detail of outcome reporting. Studies were classified as high, moderate, or low quality based on the number of “no” or “unclear” responses per the JBI criteria: high quality (1 “no” or 2 “unclear”), moderate quality (2 “no” or 2–4 “unclear”), and low quality (more than 2 “no” or over 4 “unclear”). Any disagreements were resolved through consensus among the review team.

Statistical Methods

Considering the heterogeneity and the predominance of case reports and small case series within the existing literature, a quantitative meta-analysis was deemed unfeasible. Statistical analyses were conducted using descriptive and inferential methods. Continuous variables, including lesion size, symptom duration, and follow-up period, were reported as mean and standard deviation. Categorical variables, such as presenting symptoms, vertebral level, anatomical origin, and lesion extension, were summarized as frequencies. For group comparisons of lesion size according to presenting symptoms, the Kruskal–Wallis test was used due to small sample sizes and potential nonnormality. Chi-square goodness-of-fit tests were employed to assess the distribution of vertebral level involvement, anatomical origin, clinical presentation, and lesion extension. A p-value of less than 0.05 was considered statistically significant.

Results

Study Selection

A total of 123 records were identified from electronic databases (Scopus: 59, PubMed: 31, and Embase: 33). After removal of 35 duplicate records, 88 unique records remained for screening. Of these, 47 records were excluded based on title and abstract screening, and 41 reports were sought for full-text retrieval. Four reports could not be retrieved. Of the 37 reports assessed for eligibility, 10 were excluded (7 due to hereditary exostosis, and three because lesions involved the cervical or thoracic regions), resulting in 27 studies included from database sources. Additionally, 18 records were identified through citation searching. All were retrieved and assessed, with six further reports excluded due to hereditary exostosis, yielding 12 additional studies. In total, 39 studies met the inclusion criteria and were included in the qualitative synthesis ([Fig. 1]).

Fig. 1 PRISMA 2020 flowchart illustrating the study selection process for the systematic review of osteochondroma of the lumbar spine.

Study Characteristics and Risk of Bias Assessment

A total of 39 studies comprising 48 patients with OC of the lumbar spine were included in the present review.[9] [10] [11] [12] [13] [14] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] Publication years ranged from 1954 to 2024, with the majority of reports published after 2000. Most studies were individual case reports or small case series and originated from a diverse range of geographical regions ([Table 1]). Quality appraisal using JBI tools rated 29 studies as high quality, eight as moderate, and two as low. Full quality scoring is in [Table 2].

Table 1 Summary of demographic, clinical, radiological, and surgical characteristics for patients with lumbar spine osteochondroma included in the systematic review

Author	Year	Gender	Age	Level	Origin	Extension	Size (mm)	Presentation	Duration of symptoms (Month)	Treatment Approach	Extent of resection	Outcome	Follow-up (mo)
Index case	2024	Female	41	L5	IAP	IC + PS	29	Radiculopathy	6	PWI	En bloc	Improved	12
Sato et al[1]	2022	Male	79	L5	IAP	IC	10[a]	Radiculopathy	NA	PWOI	En bloc	Improved	NA
Suwak et al[2]	2021	Male	18	L5	SP	PS	38	Palpable lumbar mass	12	PWOI (laminectomy)	En bloc	Improved	3
Zaher et al[3]	2021	Male	30	L5	SP	PS	42	Palpable lumbar mass	24	PWOI (laminectomy)	En bloc	Improved	48
Lin et al[4]	2021	Female	73	L3	IAP	IC	15	Radiculopathy + neurogenic claudication	48	PWI	En bloc	Improved	NA
Shigekiyo et al[5]	2019	Male	62	L4	IAP	IC	10[a]	Radiculopathy	12	PWOI (hemilaminotomy)	En bloc	Improved	NA
	2019	Male	61	L4	IAP	IC	9[a]	Radiculopathy	24	PWOI (hemilaminotomy)	En bloc	Improved	NA
Carrera et al[6]	2017	Male	50	L4	IAP	IC	8[a]	LBP + Radiculopathy	48	PWOI	En bloc	Improved	NA
Rosa et al[7]	2016	Male	70	L5	SP	PS	70	LBP	12	PWOI (laminectomy)	En bloc	Improved	12
Rymarczuk et al[8]	2015	Male	40	L5	VB	RP	78	LBP + Abdominal pain	NA	AWOI (transperitoneal)	En bloc	Improved	12
Sciubba et al[9]	2015	Female	31	L1	NA	NA	NA	NA	NA	PWOI	En bloc	Improved	NA
	2015	Male	61	L2	NA	NA	NA	NA	NA	PWOI	Intralesional	Improved	NA
	2015	Female	62	L2	NA	NA	NA	NA	NA	PWOI	Intralesional	Improved	NA
	2015	Male	32	L4	NA	NA	NA	NA	NA	PWOI	Intralesional	Improved	NA
	2015	Male	38	L4	NA	NA	NA	NA	NA	PWOI	En bloc	Improved	NA
	2015	Male	19	L5	NA	NA	NA	NA	NA	PWOI	En bloc	Improved	NA
	2015	Male	20	L5	NA	NA	NA	NA	NA	PWOI	En bloc	Improved	NA
Sade et al[10]	2015	Female	24	L4	SP	PS	30[a]	LBP	NA	PWOI	En bloc	Improved	NA
	2015	Female	15	L4	SP	PS	35[a]	LBP	NA	PWOI	En bloc	Improved	NA
Hancock et al[11]	2015	Female	16	L5	TP	PS	40	LBP	1	PWOI	En bloc	Improved	8
Hadhri et al[12]	2015	Male	20	L3	SP	PS	42	LBP	12	PWOI (hemilaminotomy)	En bloc	Improved	24
Kuraishi et al[13]	2014	Female	48	L4	IAP	IC	NA	Radiculopathy	NA	PWOI (hemilaminotomy)	En bloc	Improved	36
	2014	Male	32	L4	IAP	IC	NA	Radiculopathy	24	PWOI (hemilaminotomy)	En bloc	Improved	19
	2014	Male	57	L4	IAP	IC	NA	Radiculopathy	72	PWOI (laminectomy)	En bloc	Improved	84
Pourtaheri et al[14]	2014	Male	11	L3	IAP	IC	48	Hip flexion contracture	NA	PWI	En bloc	Improved	54
Zaijun et al[15]	2013	Male	43	L4	SP	PS	NA	LBP	NA	PWOI	En bloc	Improved	48
Natale et al[16]	2013	Female	56	L2	IAP	IC	11[a]	Radiculopathy	2	PWOI (interlaminar)	En bloc	Improved	8
Zaijun et al[15]	2013	Female	68	L2	TP	PS	NA	LBP	NA	PWI	En bloc	Improved	2
Woo et al[17]	2010	Male	54	L3	IAP	IC	7[a]	Radiculopathy	2	PWOI	En bloc	Improved	3
Gunay et al[18]	2010	Female	32	L3	SP	PS	NA	Abdominal pain	NA	PWOI	En bloc	Improved	48
Kahveci et al[19]	2010	Male	48	L3	IAP	IC	7[a]	Radiculopathy and foot drop	24	PWOI (hemilaminotomy)	En bloc	Improved	NA
Lotfinia et al[20]	2010	Male	29	L4	Pedicle	IC	NA	Radiculopathy	NA	PWOI (laminectomy)	En bloc	Improved	24
	2010	Male	58	L5	VB	NA	NA	Radiculopathy	NA	PWOI (laminectomy)	En bloc	Improved	24
Choi et al[21]	2010	Female	57	L3	IAP	IC	10[a]	Radiculopathy	2	PWI	En bloc	Improved	NA
Yagi et al[22]	2009	Male	69	L4	IAP	PS	50	LBP	NA	Biopsy and ablation of facet (due to HIV + )	Biopsy	Improved	6
Xu et al[23]	2009	Female	38	L5	IAP	IC	11	Radiculopathy	5	PWOI	En bloc	Improved	NA
Yagi et al[22]	2009	Male	72	L4	IAP	PS	30	LBP	NA	PWOI	En bloc	Improved	24
Hassankhani[24]	2009	Female	16	L3	SP	PS	50	Scoliosis	24	PWOI	En bloc	Improved	19
Barsa et al[25]	2009	Male	75	L3	IAP	IC	NA	Neurogenic claudication	NA	PWI	En bloc	Improved	48
Byung-June et al[26]	2007	Male	23	L5	IAP	IC	8[a]	LBP + Radiculopathy	1	PWOI (laminectomy)	En bloc	Improved	NA
Bess et al[27]	2005	Female	42	L3	SP	PS	NA	Radiculopathy	NA	NSAID	NA	Improved	132
	2005	Male	25	L3	SP	PS	NA	Palpable lumbar mass	NA	PWOI	NA	Improved	24
Gille et al[28]	2005	Female	28	L4	PE	NA	NA	Radiculopathy	NA	PWOI (laminectomy)	En bloc	Improved	NA
Bess et al[27]	2005	Male	23	L2	SP	PS	NA	Palpable lumbar mass	NA	PWI	NA	Partially Improved	NA
Gürkanlar et al[29]	2004	Male	35	L4	IAP	IC	6[a]	Radiculopathy	NA	PWOI	En bloc	Improved	NA
Ohtori et al[30]	2003	Female	55	L4	IAP	IC	8[a]	Radiculopathy	3	PWOI (interlaminar)	En bloc	Improved	6
	2003	Male	56	L3	SAP	IC	9[a]	Radiculopathy	5	PWI	En bloc	Improved	72
Sakai et al[31]	2002	Female	68	L3	IAP	IC	7[a]	Radiculopathy	72	PWOI (laminectomy)	En bloc	Improved	NA
Fiumara et al[32]	1999	Female	35	L5	IAP	IC	13[a]	Radiculopathy	72	PWOI (interlaminar)	En bloc	Improved	NA
Van der Sluis et al[33]	1992	Female	26	L4	IAP	NA	NA	LBP + Radiculopathy	24	PWOI	NA	Improved	NA
Espaziante et al[34]	1988	NA	NA	L4	PE	NA	NA	Radiculopathy	9	PWOI	NA	Improved	NA
Malat et al[35]	1986	Male	56	L1	VB	IC	30	Cauda equine	4	PWOI (laminectomy)	En bloc	Improved	NA
Esposito et al[36]	1985	Male	14	L3	TP	PS	28	Scoliosis	NA	PWOI (paraspinal)	En bloc	Improved	15
Borne et al[37]	1976	Male	65	L3	NA	NA	NA	Radiculopathy	7	PWOI (laminectomy)	NA	NA	NA
Twersky et al[38]	1975	NA	13	L4	VB	NA	NA	LBP + Radiculopathy	9	PWOI	NA	Improved	NA
Gokay et al[39]	1954	Female	24	L3	PE	IC + PS	75	Cauda equine	NA	PWOI (laminectomy)	Subtotal	Recurrence	NA

Abbreviations: AWOI, anterior without instrumentation; IAP, inferior articular process; IC, intracanalicular component; LBP, low back pain; NA, not available; PE, pedicle; PS, paraspinal component; PWI, posterior with instrumentation; PWOI, posterior without instrumentation; RP, retroperitoneal; SAP, superior articular process; SP, spinous process; TP, transverse process; VB, vertebral body.

^a Indicates maximum dimension reported in original study.

Table 2 Quality appraisal of included studies using the Joanna Briggs Institute (JBI) critical appraisal checklist. Each study was evaluated across eight domains (Q1–Q8), with responses coded as Yes (Y), Unclear (U), or Not Applicable (N/A). Overall methodological quality was categorized as High, Moderate, or Low based on domain performance

Author	Q1	Q2	Q3	Q4	Q5	Q6	Q7	Q8	Quality
Sato et al[1]	Y	U	Y	U	Y	NA	U	Y	Moderate
Suwak et al[2]	Y	Y	Y	Y	Y	Y	Y	Y	High
Zaher et al[3]	Y	Y	Y	Y	Y	Y	Y	Y	High
Lin et al[4]	Y	Y	Y	Y	Y	Y	U	Y	High
Shigekiyo et al[5]	Y	Y	Y	U	Y	U	Y	Y	High
Carrera et al[6]	Y	Y	Y	U	Y	Y	U	Y	High
Rosa et al[7]	Y	Y	Y	Y	Y	Y	Y	Y	High
Rymarczuk et al[8]	Y	Y	Y	Y	Y	Y	Y	Y	High
Sciubba et al[9]	Y	U	U	Y	Y	NA	NA	Y	Moderate
Sade et al[10]	Y	U	Y	Y	Y	U	Y	Y	High
Hancock et al[11]	Y	Y	Y	Y	Y	Y	Y	Y	High
Hadhri et al[12]	Y	Y	Y	Y	Y	Y	Y	Y	High
Kuraishi et al[13]	Y	U	Y	Y	Y	Y	Y	Y	High
Pourtaheri et al[14]	Y	Y	Y	Y	Y	Y	Y	Y	High
Zaijun et al[15]	Y	U	Y	Y	Y	Y	Y	Y	High
Natale et al[16]	Y	Y	Y	U	Y	Y	Y	Y	High
Woo et al[17]	Y	Y	Y	U	Y	Y	Y	Y	High
Gunay et al[18]	Y	U	Y	Y	Y	Y	Y	Y	High
Kahveci et al[19]	Y	Y	Y	Y	Y	Y	Y	Y	High
Lotfinia et al[20]	Y	Y	Y	NA	Y	Y	Y	Y	High
Choi et al[21]	Y	Y	Y	Y	Y	U	U	Y	High
Yagi et al[22]	Y	Y	Y	Y	Y	U	Y	U	High
Xu et al[23]	Y	Y	Y	Y	Y	U	Y	Y	High
Hassankhani[24]	Y	Y	Y	Y	Y	Y	Y	Y	High
Barsa et al[25]	Y	Y	Y	U	Y	U	U	Y	Moderate
Byung-June et al[26]	Y	Y	Y	U	Y	U	Y	Y	High
Gille et al[28]	Y	Y	U	U	Y	U	U	Y	Moderate
Bess et al[27]	Y	Y	U	U	Y	Y	U	Y	Moderate
Gürkanlar et al[29]	Y	Y	Y	U	Y	U	U	Y	Moderate
Ohtori et al[30]	Y	Y	Y	Y	Y	Y	Y	Y	High
Sakai et al[31]	Y	Y	Y	Y	Y	U	U	Y	High
Fiumara et al[32]	Y	Y	Y	Y	Y	U	U	Y	High
Van der Sluis et al[33]	Y	Y	Y	U	Y	U	U	Y	Moderate
Espaziante et al[34]	U	U	Y	Y	Y	U	U	U	Low
Malat et al[35]	Y	Y	Y	Y	Y	U	U	Y	High
Esposito et al[36]	Y	Y	Y	U	Y	Y	Y	Y	High
Borne et al[37]	Y	Y	U	U	Y	U	U	U	Low
Twersky et al[38]	U	Y	Y	U	Y	Y	U	Y	Moderate
Gokay et al[39]	Y	Y	Y	Y	Y	Y	U	Y	High
%	95	82.5	90	62.5	100	60	57.5	92.5

Patient Demographics and Tumor Characteristics

Fifty-six patients with nonsyndromic lumbar spine OC were identified ([Table 3]), including 33 males (59%), 21 females (37%), and 2 with unreported sex (4%). The average patient age was 42 years (range, 11–79 years). The average duration of symptoms before diagnosis was 17.8 ± 20.5 months, and the follow-up period averaged 30 months.

Table 3 Summary of demographic, clinical, and surgical characteristics in patients with lumbar spine osteochondroma

	Mean ± SD or n	p-Value
Gender (female:male)	33:21 (1.6:1)
Age (y)	42.1 ± 19.6
Duration of the symptoms (mo)	17.8 ± 20.5
Duration of the follow-up (mo)	29.7 ± 30
Size
Overall	29.7 ± 22.2	0.0003[a]
In radiculopathy	11.3 ± 6.3
In low back pain	40.1 ± 24.0
In palpable mass	40.0 ± 2.8
Level
L1	2	0.0004[a]
L2	5
L3	16
L4	20
L5	13
Origin
IAP	24	<0.001[a]
SP	12
VB	4
TP	3
Pedicle	2
Posterior elements	2
SAP	1
Anterior (VB + Pedicle + TP): posterior	9:39	<0.001[a]
Extension
Intracanalicular	25	0.36
Paraspinal	19
Retroperitoneal	1

Note: Categorical variables are presented as counts (n) or ratios; continuous variables are expressed as mean ± standard deviation (SD). For group comparisons, p-values were calculated using the chi-square goodness-of-fit test for categorical variables and the Kruskal–Wallis test for continuous variables. A p-value of < 0.05 was considered statistically significant.

^a Significant values.

The mean lesion size among all cases with available data was 29.7 ± 22.2 mm. Comparison of lesion size among patients presenting with radiculopathy (mean: 10.9 ± 5.5 mm), low back pain (mean: 45.3 ± 21.5 mm), and palpable mass (mean: 40.0 ± 2.8 mm) revealed a statistically significant difference in lesion size across groups (p = 0.00034). Lesion size differs significantly by clinical presentation, with much larger lesions in LBP and mass groups than in radiculopathy.

The most common vertebral level involved was L4 (36%), followed by L3 (28%), L5 (23.5%), L2 (9%), and L1 (3.5%). There was a statistically significant difference in the distribution of affected vertebral levels among patients with lumbar spine OC (p = 0.00045), with involvement most frequently observed at L4. This finding indicates that the occurrence of OC is not evenly distributed across lumbar levels. ([Table 4])

Table 4 Distribution of clinical presentation, treatment approaches, extent of resection, and outcomes in patients with lumbar spine osteochondroma

	n	p-Value
Presentation
Radiculopathy	28	<0.001[a]
Low back pain	14
Palpable mass	4
Cauda equine	2
Claudication	2
Abdominal pain	2
Scoliosis	2
Hip flexion contracture	1
Treatment approach
Posterior without instrumentation (POWI)	45	<0.001[a]
Posterior with instrumentation (PWI)	8
Anterior	1
NSAID	1
Ablation	1
POWI vs. PWI	45:8	<0.001[a]
Extent of resection
En bloc	44	<0.001[a]
Intralesional	3
Subtotal	1
Biopsy	1
En bloc vs. others	9:5	<0.001[a]
Outcome
Improved	53	<0.001[a]
Partial improvement	1
Recurrence	1

Note: Frequencies are reported for each category. p-Values reflect statistical comparisons using the chi-square goodness-of-fit test. A p-value less than 0.05 was considered statistically significant.

^a Significant comparisons.

The inferior articular process was the most frequent site of origin (43%), followed by the spinous process (21.5%), vertebral body (7%), transverse process (5.5%), pedicle (3.5%), posterior elements (3.5%), and superior articular process (2%). In 14% of cases, the exact site of origin was not specified. There was a highly significant difference in the distribution of anatomical origin among lumbar OCs (p = 1.8 × 10⁻¹¹), with the inferior articular process being the most frequently involved site, followed by the spinous process and other locations. This finding suggests a clear predilection for specific sites of origin within the lumbar spine. There was a highly significant predilection for lumbar OC to originate from posterior elements rather than the anterior vertebral body (p < 0.001), with the vast majority of lesions arising from posterior structures.

Regarding tumor extension, 45% showed intracanalicular growth, 34% were paraspinal, 2% were retroperitoneal, and extension was not specified in 19%. There was no statistically significant difference between the frequencies of intracanalicular and paraspinal extension among lumbar OCs (p = 0.36).

Clinical Presentation

Radiculopathy was the most common clinical presentation, affecting 50% of patients. It was followed by low back pain in 25%, and palpable mass in 7%. Less frequent initial symptoms included cauda equina syndrome (3.5%), claudication (3.5%), abdominal pain (3.5%), scoliosis (3.5%), and hip flexion contracture (2%). A chi-square goodness-of-fit test showed a statistically significant difference in symptom frequency (p < 0.001), with radiculopathy and low back pain being the most prevalent.

Treatment and Outcomes

The majority of patients (80%) underwent surgical treatment via a posterior approach without instrumentation, whereas an additional 14% required posterior instrumentation due to spinal instability. An anterior approach was employed in one patient (2%). Nonoperative treatments, including NSAIDs and ablation, were administered to two patients (2% each). Regarding resection methods, en bloc excision was accomplished in 78.5% of cases, intralesional resection in 5%, subtotal resection in 2%, and biopsy alone in 2%. A chi-square test comparing en bloc resection to all other surgical approaches revealed a significant preference for en bloc removal (p < 0.001), with en bloc resection performed in the majority of cases. At the final follow-up, 94% of patients exhibited complete symptomatic improvement. Partial improvement and recurrence were each observed in one patient (2% each).

Case Presentation

A 41-year-old woman presented with a 14-month history of low back pain and a 6-month history of left leg radiculopathy (NRS 7/10), affecting the lateral shin and plantar foot. She also reported milder symptoms on the right side. Her past medical and surgical history was noncontributory. Neurological examination revealed normal motor strength except for left ankle plantar flexion (four-fifths), accompanied by a diminished left Achilles reflex. The straight leg raise test was positive on the left. Magnetic resonance imaging (MRI) demonstrated bilateral L5-S1 facet lesions (the largest measuring 27 mm × 6 mm) with intracanalicular extension, resulting in foraminal narrowing at L5-S1 and compression of the left S1 lateral recess ([Fig. 2]). Computed tomography (CT) confirmed these findings. Blood investigations, including calcium, phosphorus, and alkaline phosphatase, were within normal limits.

Fig. 2 (A) T2W MR in sagittal (left) and axial cut (Right). Left: arrow shows the Left L5-S1 intervertebral foramen with obvious stenosis. The star sign shows the lesion arising from the inferior articular process of L5. Right: the axial cut of T2W MR at the level of L5-S1 Facet shows low-intensity bilateral round masses (arrow), which arise from the Inferior articular process of L5. (B) The Left shows a sagittal cut of CT, and the arrow indicates the intracanalicular part of the Lesion. The right image shows the High density of the lesion. (C) Postoperative CT, the left image indicates no residual tumor, and the right image shows L4, L5, and S1 fixation with pedicular screw.

The patient underwent a posterior en bloc excision along with L5-S1 transforaminal lumbar interbody fusion, accompanied by posterior fixation from L4 to S1, owing to bilateral facet involvement. Pathological analysis revealed mature hyaline cartilage overlying trabecular bone, consistent with a benign OC (Enneking stage 1). The postoperative course was uneventful, with complete resolution of radicular pain. At 6- and 12-month follow-up assessments, the patient remained asymptomatic, exhibiting stable fusion and no signs of recurrence.

Discussion

OCs are benign cartilage-capped bone tumors that arise through endochondral ossification. Although common in extremities, spinal involvement is rare. Our review confirms the lumbar spine as the least frequently affected region, but with a notable preference for L4 and L5. Most lesions involved the posterior column, particularly the inferior articular process. Consistent with the literature, patients presented in their fourth decade, with a male predominance.[1] [5] [6] [7] [8] [9] While early reports suggested lumbar OCs rarely cause symptoms, our findings indicate that intracanalicular growth is common and often produces radiculopathy.

Based on imaging and clinical presentation, we observed three patterns[1]: small intracanalicular lesions with radiculopathy,[2] large extra-canalicular lesions causing back pain or mass effect, and[3] atypical presentations like scoliosis or foot drop. Despite their slow growth, the average symptom duration was 18.5 months, highlighting the diagnostic challenge.

Several reports support conservative management in select, minimally symptomatic patients.[32] [37] However, surgical intervention is generally favored when neural elements are at risk. Surgery remains the mainstay of treatment. Posterior decompression was sufficient in most cases. Instrumentation was reserved for instability, as illustrated in our case. En bloc resection—used in over 75%—resulted in excellent outcomes. Completeness of resection, especially removal of the cartilage cap, is critical to prevent recurrence.[5] [10] [37] [38] Incomplete removal of the tumor body or cartilage cap can lead to a higher risk of recurrence.[19] Recurrence rates after resection of exostosis are approximately 2%.[49] [50] Although rare, malignant transformation to chondrosarcoma has also been documented, typically in adults with large or growing lesions. Only one such case was identified in our review, emphasizing the need for long-term follow-up in selected patients.[51]

Due to the risk of late recurrence and rare malignant transformation of OC, especially in solitary spinal lesions, long-term monitoring is advised. Postoperative imaging should consist of MRI or CT scans at 6 and 12 months to verify complete removal and spinal stability, followed by clinical assessments every 2 years with imaging only if new or worsening symptoms appear. For cases involving incomplete cap removal or large lesions near neural structures, annual MRI scans for up to 5 years might be advisable.[52] Dynamic imaging, such as flexion-extension radiographs and MRI, can be useful for assessing postoperative spinal alignment, detecting motion-induced neural compression, or distinguishing scar tissue from tumor recurrence. Using these dynamic techniques allows for early detection of subtle instability or regrowth, helping to improve functional outcomes and ensure long-lasting tumor control.

In patients with multiple OCs, baseline whole-body MRI or bone scan and periodic MRI of the spine/trunk are recommended because these patients have higher transformation and spinal involvement rates. For HMO patients with trunk/proximal lesions, yearly MRI after skeletal maturity is recommended.[53]

Conclusion

OCs in the lumbar spine are uncommon lesions, primarily originating from the inferior articular process. Unlike previous assumptions, they frequently cause radiculopathy due to extension into the spinal canal. Surgical removal, particularly en bloc resection, is highly effective, leading to excellent results and a low rate of recurrence. Conservative treatment might be suitable for asymptomatic patients. Early diagnosis and personalized treatment strategies are crucial to prevent long-term complications and ensure optimal recovery.

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