Incompetent intraosseous perforating vein was initially reported in 1962 by Schobinger and Weinstein (1). They described how paratibial varicose veins were connected to intraosseous venous dilation. Approximately two decades ago, the term “abnormal intraosseous venous drainage” appeared, but it has recently been replaced with the term “bone perforator” (2). However, the terms “intraosseous perforating veins” or “transosseous veins” seem more suitable for these veins that perforate the bone cortex and are both physiological and numerous. They allow for bone venous drainage toward the systemic circulation, and can become pathological, dilated, incompetent, leading to leg varicose veins. Therefore, the terms “incompetent intraosseous perforator vein” or “incompetent transosseous veins” are more accurate (3).

Several pathophysiological hypotheses can be proposed, including:

(i) Malformations during embryogenesis, which may involve the absence of the posterior main feeder hole or hypo- or agenesis of the tibia feeder vein.

(ii) Traumatic complications. either due to localized trauma resulting in the closure of the posterior main feeder or transverse diaphyseal fractures leading to interruption of venous continuity.

(iii) Elevated pressure in the tibia feeder vein, secondary to primary or postthrombotic reflux in the posterior tibial vein, which could potentially be associated with proximal venous reflux. In this case, the posterior feeder orifice, which is physiologically the main drainage pathway for the intraosseous venous system, becomes a point of reflux. This forces the intraosseous vein drainage to use other secondary cortical orifices, which may progressively widen due to vascular hyperflow.

(iv) A pathological transosseous vein could be a persistent embryonic vein, while the other bone drainage pathways remain normal (3).

The typical causes of varicose veins are associated with reflux in the great or small saphenous veins. Unusual causes of varicose veins include vulvoperineal varicosity, persistent sciatic vein incompetence, round ligament varicosity, intraosseous perforating vein incompetence, Klippel-Trenaunay syndrome, and portosystemic collateral pathways. Jung et al. (4) previously reported an incidence of 0.2% for intraosseous perforating vein incompetence in three out of 1,350 patients with varicose veins.

Cases of intraosseous perforating vein incompetence primarily present in the anteromedial side of the mid-shaft of the tibia and are connected to pretibial varices. A previous report has documented an extremely rare case in the fibula (5). The purpose of this study is to examine the clinical manifestations, diagnostic methods, and appropriate treatments of intraosseous perforating vein incompetence.

This study included patients who visited our hospital with lower extremity varicose veins between June 2016 and October 2021 and were diagnosed with intraosseous perforating vein incompetence originating from the mid-shaft of the tibia. The diagnosis of intraosseous perforating vein incompetence was made using color Doppler ultrasound imaging (Fig. 1). After confirming deep vein patency, a reflux test was performed with the patient in a standing position.

Figure 1. (A) Color Doppler ultrasonography test: pretibial varices connected to perforating vein through the defect of the tibial cortex. (B) Reflux graph of the perforating vein.

Ethical considerations were taken into account throughout the conduct of this study. The research protocol was reviewed and approved by the public Institutional Review Board (IRB No. P01-202308-01-006), prior to the study initiation. Informed consent was waived due to the nature of the study. The study was conducted in accordance with the principles of the Declaration of Helsinki and other applicable ethical guidelines for research involving human subjects.

The statistical analysis of this study was conducted using descriptive statistics which were used to summarize the characteristics of the patients, including measures of central tendency (mean, median), and dispersion (standard deviation, range). A p-value of <0.05 was used as the threshold for statistical significance. All statistical analyses were conducted using Excel (Microsoft Corporation, Redmond, WA, USA).

A total of 5,481 patients with lower extremity varicose veins visited our clinic. Among them, seven patients (0.13%) were diagnosed with intraosseous perforating vein incompetence originating from the mid-shaft of the tibia. Out of these seven patients, six were male and one was female, with ages ranging from 41 to 67 years old (Table 1). While the patients experienced common symptoms of lower extremity varicose veins such as heaviness, cramping, tingling, swelling and discomfort, there were no localized symptoms specifically related to the tibia area.

Table 1 . Cases summary.

Case	Sex/age	Perf.size (mm)	Symptoms	Localizes symptoms of tibial area	Combined reflux of saphenous vein	Operation
1	M/41	3	Heaviness tingling	None	Both GSV, Lt perf	Yes
2	M/41	2	Heaviness swelling	None	Both GSV, Lt SSV, Lt perf	Yes
3	F/59	3.5	Cramping	None	Rt perf	Yes
4	M/67	3	Heaviness	None	Rt GSV, Rt perf	Yes
5	M/61	1.5	Heaviness	None	Lt GSV, Rt perf	No
6	M/62	1.3	None	None	Rt perf	No
7	M/62	1	None	None	Lt perf	No

Perf: incompetent intraosseous perforating vein, GSV: great saphenous vein, SSV: small saphenous vein, Lt: left, Rt: right..

Among the seven patients, four had combined reflux of the saphenous vein, while three had isolated intraosseous perforating vein incompetence. The diameter of the perforating veins ranged from 1 to 3.5 mm, and they were connected to pretibial varices (Fig. 2).

Figure 2. Pretibial varices of the left leg (before and after mapping).

Surgical treatment was performed for the four patients by perforating vein ligation and phlebectomy with an incision under local anesthesia (Fig. 3). In contrast, three patients with perforating vein diameters less than 2 mm, no symptoms, and minimal pretibial varicosities were observed without surgical intervention.

Figure 3. Dissecting from pretibial varices to the origin of perforating vein.

Among the seven patients diagnosed with intraosseous perforating vein incompetence, three patients did not require treatment as they did not show symptoms and had minimal varicose veins. The remaining four patients who underwent surgery did not present any local symptoms around the tibia. Previous studies by de Moraes et al. (6) observed chronic pain and repeated erysipelas in the mid-shaft of the tibia, while Kwee et al. (7) reported a case in which the patient complained of painful pretibial swelling. Rezaie et al. (8) presented a case of severe leg pain with difficulties walking or sleeping. Just as symptoms can vary in varicose veins related to the saphenous vein, the degree of symptoms can also vary in varicose veins related to intraosseous perforating vein incompetence.

Intraosseous perforating vein incompetence can be diagnosed as follows: in patients with varicose veins on the midportion of the shin, tibial depression caused by tibial bony cortex defect can be palpated and verified using Doppler ultrasound. Doppler ultrasound is the most useful method for facilitating a simple and accurate diagnosis of intraosseous perforating vein incompetence (Fig. 1). CT venography or MRI can also be utilized for diagnosis. These tests confirm that the enlarged intraosseous vein in the tibia, the perforating vein passing through the enlarged tibial nutrient canal, and its connection to the pretibial varices. Tibial cortical defect and nutrient canal can also be detected on X-ray (4,9).

Differential diagnoses include arteriovenous malformation, venous malformation, and hemangiomas. MRI may also be of great help for differential diagnosis (10).

Ambulatory phlebectomy, perforating vein ligation, and percutaneous ablation, are the usual treatment options (11). Intraosseous perforating vein incompetence is usually treated using ambulatory phlebectomy and perforating vein ligation (7,8,12). Sclerotherapy is generally not considered due to the intraosseous communication of the varix (12). However, there are doctors who choose to treat it with sclerotherapy. In a case report by Peh et al. (13), intraosseous perforating vein incompetence was treated using image-guided sclerotherapy with absolute alcohol.

Intraosseous perforating vein incompetence is a very rare cause of varicose veins in the lower extrimities, occurred mostly in the anteromedial side of the mid-shaft of the tibia and leading to pretibial varices. This condition is easily overlooked due to its rarity. However, with adequate knowledge, intraosseous perforating vein incompetence can be accurately diagnosed using Doppler ultrasound alone and easily treated by perforating vein ligation and phlebectomy.