Foot and Ankle Surgery 20 (2014) 67–70
Contents lists available at ScienceDirect
Foot and Ankle Surgery journal homepage: www.elsevier.com/locate/fas
Ankle position affects dorsalis pedis artery exposure in anterior ankle arthroscopy Priyesh Ashok Karia BSc – Basic Medical Sciences with Anatomya,*, Yogesh Nathdwarawala MBBS, MS (Orth), MSc (Orth.Eng.), (FRCS Orth.)b,1, Matthew Szarko Ph.D.c,2 a
Division of Biomedical Sciences, St. George’s University of London, Cranmer Terrace, London SW17 0RE, United Kingdom Nevill Hall Hospital, Brecon Road, Abergavenny NP7 7EG, United Kingdom c Division of Biomedical Sciences, St. George’s University of London, Rm 0130, Jenner Wing Basement, Cranmer Terrace, London SW17 0RE, United Kingdom b
A R T I C L E I N F O
A B S T R A C T
Article history: Received 27 July 2013 Received in revised form 11 November 2013 Accepted 15 November 2013
Background: In anterior ankle arthroscopy, the anterior working area (AWA) is restricted by the presence of the dorsalis pedis artery (DPA) and tendons. Pseudoaneurysms caused by iatrogenic damage to the DPA are difficult to identify intraoperatively. In knee arthroscopy, risk of popliteal artery damage is reduced in the flexed position [1]. This study investigates how DPA movement is affected by dorsiflexion and plantarflexion with the aim of identifying the positions providing the greatest AWA. Methods: Twelve cadaveric ankles were dissected to access the DPA. While distracted, ankles were progressively dorsiflexed at 58 intervals from maximum plantarflexion. DPA and tibialis anterior tendon (TA) movement at each 58 interval was measured by their respective distances from the inferior border of the medial malleolus. Results: Mean ankle dorsiflexion was 24.58 1.308 with all specimens showing anterior DPA and TA movement as dorsiflexion increased. Mean DPA and TA movement at maximum dorsiflexion was 3.58 0.29 mm and 2.92 0.34 mm respectively. A ratio of 1:1.23 relates TA and DPA movement (in mm), and a ratio of 10:1.46 relates dorsiflexion angle to DPA movement (in mm). Conclusion: Anterior movement of the dorsalis pedis artery during dorsiflexion increases the AWA for anterior arthroscopy. Increasing the AWA with maximal dorsiflexion may prove to be a valuable method for lowering the risk of iatrogenic DPA damage. Additionally, increased AWA may allow the use of larger diameter surgical instruments allowing greater control and a reduction in operation time. ß 2013 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
Keywords: Ankle arthroscopy Dorsalis pedis artery
1. Introduction Ankle injuries are a common complaint and form the primary site of injury in more than 30% of all sports [2]. Conditions including chronic ankle instability, anterior ankle impingement syndrome, osteochondral lesions and osteophyte formation often require arthroscopic intervention when conservative management has failed [3]. Additionally, ankle arthroscopy can be indicated to identify the underlying cause of undiagnosed ankle pain as well as treating the cause during the procedure [3]. The ankle was initially thought to be an unsuitable joint for arthroscopy due to the narrow joint space that reduces the anterior
* Corresponding author. E-mail addresses: [email protected] (P.A. Karia), [email protected] (Y. Nathdwarawala), [email protected] (M. Szarko). 1 Tel: +44 7961482498. 2 Tel.: +44 020 8725 2831; fax: +44 020 8725 3326.
working area (AWA) and places the surrounding tendinous and vascular anatomical structures at risk of intraoperative damage [4]. The development of fibre optic arthroscopes has allowed ankle arthroscopies to be conducted when the ankle is placed in a distracted position that increases the joint space by pulling the foot away from the lower leg [5,6]. In anterior ankle arthroscopies, the AWA is particularly important as it allows space for the manoeuvring of surgical instruments and the arthroscope itself. However, the AWA is limited by anatomical structures crossing anterior to the ankle joint. These include the tendons of the anterior compartment muscles of the leg and the anterior neurovascular bundle, consisting of the dorsalis pedis artery (DPA), its bilateral deep veins and the deep fibular nerve. Access to the AWA in ankle arthroscopies are typically through anteromedial (medial to tibialis anterior tendon) and anterolateral (lateral to extensor digitorum longus tendon) portals [7]. Incorrect portal placement and limited AWA can increase the risk of intraoperative injury to tendons, vasculature, and nerves [8,9]. Complication rates after
1268-7731/$ – see front matter ß 2013 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.fas.2013.11.004
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P.A. Karia et al. / Foot and Ankle Surgery 20 (2014) 67–70
anterior ankle arthroscopy range between 3.4% and 9% [8,10]. Due to its close relationship to the anterior joint capsule, the DPA is the most affected neurovascular structure [11]. Damage to the DPA is difficult to assess intraoperatively due the maintenance of a bloodless joint through use of a thigh tourniquet [8]. Undiagnosed injury to the DPA may cause complications such as pseudoaneurysms which are more likely to rupture than typical aneurysms and if left untreated can lead to haemarthrosis and compartment syndrome [11]. Vascular complications can also occur during portal placement where branches of the dorsalis pedis artery give off smaller malleolar arteries [12]. Numerous studies have investigated ways to increase the AWA in an attempt to identify procedures for limiting intraoperative damage during anterior ankle arthroscopies. Distraction techniques tighten the anterior joint capsule by pulling the foot away from the lower leg. These techniques are used as they enhance the ability for pathology identification but, as they do not increase the AWA, they do not necessarily aid pathology treatment [13]. Dorsiflexion of the ankle has been found to increase the AWA and allow easier removal of loose bodies [13]. Forced plantarflexion creates traction that tightens the anterior ankle joint capsule and results in a reduced AWA [14]. A limited study using computed tomography (CT) found that the DPA was moved further from the ankle joint in dorsiflexion when compared to distraction [15]. A cadaveric and an MRI study looked at the position of the popliteal artery at different angles of knee flexion in knee arthroscopic procedures to determine the safest position [1,16]. Both studies that showed that the distance between the popliteal artery and the knee joint was greatest at knee flexion [1,16]. The present study combines distraction and dorsiflexion in an attempt to quantify the changes in AWA size when dorsiflexion is maximised. Additionally, in order to increase the intraoperative practicality of distraction and dorsiflexion, the anterior movement of the DPA is correlated to the anterior movement of the tibialis anterior tendon, which can be easily identified and measured during arthroscopy.
Fig. 1. Image illustrating the inferior border of the medial malleolus (IBMM) used as the fixed reference point of the ankle joint.
One end of a goniometer (Jamar, UK) was aligned immobile with the dissected posterior border of the tibial shaft and the other end aligned with the medial border of the base of the first metatarsal to measure the degree of ankle flexion and extension. The centre of the goniometer was pivoted next to the medial malleolus leaving a mobile distal end to measure the degree of ankle movement. As a beginning reference point, each ankle was distracted and then positioned in maximal plantarflexion. Ankles were then dorsiflexed at 58 intervals until maximum dorsiflexion was reached. Calliper measurements were taken between the shortest distance of the DPA and tibialis anterior tendon from the fixed reference point (IBMM) at each 58 interval. 2.3. Statistical analysis A One way analysis of variance (ANOVA) with Tukey post hoc analysis was conducted using a significance level of p 0.05. All statistical analysis was conducted using JMP 10 (USA). 2.4. Ethics
2. Materials and methods 2.1. Specimens Twelve ankles (7 left and 5 right, 8 female and 4 male) from seven soft-preserved cadavers were used in this study. The cadaveric specimens were preserved using a mixture of phenol, methylated spirits, water and glycerol in order to allow ranges of movements similar to those found in vivo [17]. 2.2. Experimental procedure The lower leg of each specimen proximal to the ankle was elevated onto a block to allow a full range of ankle motion while the specimen was placed supine on a table. The Zimmer distractor technique was adopted using cotton string that circled the leg above the talocrural joint and looped in a figure-8 distal to the midtarsal joint [15]. Thus the mid-tarsal joint was placed in a closedpacked position negating excessive movement. After distraction, the end of the string was attached to the end of the specimen table to ensure continued distraction throughout the experiment and maintain uniform distraction with all the specimens. The inferior border of the medial malleolus (IBMM) was dissected and used as a non-moveable fixed point (Fig. 1) for measurements of DPA and undissected tibialis anterior tendon (TA) movements with dorsiflexion.
All cadaveric material was donated and used in accordance with the 2004 Human Tissue Act. 3. Results Average dorsiflexion was found to be 24.58 1.308 among the twelve ankle specimens. All specimens showed anterior movement of the DPA and TA from the IBMM during dorsiflexion. The DPA showed a mean anterior movement of 3.58 0.29 mm from the IBMM during the full range of mean dorsiflexion (0–24.588). The TA achieved a mean anterior movement of 2.92 0.34 mm during the full range of dorsiflexion (0–24.588). The anterior DPA movement during dorsiflexion indicates an increase in the AWA as arterial movement away from the joint increases the area available for anterior arthroscopic procedures without risking neurovascular damage. The anterior movement of both the DPA and TA can be related to each other using a 1.23:1 ratio (mm) during dorsiflexion (Fig. 2). This ratio indicates every 1 mm of anterior TA movement is related to 1.2 mm anterior DPA movement. Measurement of anterior TA movement is easily achieved in theatre and may provide a simple method to assess increases in the AWA. Anterior DPA movement was compared among initial dorsiflexion (0–108), middle dorsiflexion (10–208), and terminal dorsiflexion (>208) (Fig. 3). Anterior DPA movement was greatest in initial dorsiflexion (1.67 mm), however no statistical difference was seen among the three stages of dorsiflexion (p 0.11).
P.A. Karia et al. / Foot and Ankle Surgery 20 (2014) 67–70
Fig. 2. The graph illustrates the association between mean DPA (&) and TA (*) movement over the full range of dorsiflexion.
69
The DPA is not visible during ankle arthroscopy and therefore it is important for the surgeon to be able to accurately predict the DPA movement upon dorsiflexion of the ankle in an attempt to gauge the size of the AWA. The present investigation has related anterior DPA movement to both anterior TA movement and increasing levels of dorsiflexion. Both anterior TA movement and ankle dorsiflexion are easily assessed in theatre and may be used to give a deeper understanding of the size of the AWA during ankle arthroscopy. Utilising a ratio of 1.23:1 allows surgeons to accurately identify anterior DPA movement based on anterior TA movement. Using this ratio, a surgeon can discern that the DPA will move anteriorly 1.23 mm for each 1 mm of anterior TA movement. Additionally, as all stages of dorsiflexion (initial, middle, and terminal) produce consistent anterior DPA movement, a 108:1.46 mm ratio can be used to identify increased AWA with dorsiflexion. Thus, using a simple goniometer, a surgeon may identify 1.46 mm of anterior DPA movement every 108 of dorsiflexion achieved. The present study has shown maximal dorsiflexion increases the space between the ankle joint and the neurovascular bundle associated with the dorsalis pedis artery. It is therefore in the best interest of the patient and surgeon for the ankle to be maximally dorsiflexed to achieve the greatest AWA. The surgeon may confirm this by measuring either tibialis anterior tendon movement or amount of ankle dorsiflexion. Increased AWA allows the introduction of a larger diameter arthroscope, allowing larger flow of saline into the joint space [18]. The greater field of view of the joint space with a large diameter arthroscope could also help reduce operation time by speeding up diagnosis and treatment [18]. The limited availability of soft-preserved cadavers confines this study to use specimens from the elderly population, therefore not reflecting the age of the patient population undergoing ankle arthroscopy. However, younger cadavers are more likely to have musculoskeletal pathology, which would affect this study. 5. Conclusion
Fig. 3. Mean movement and standard error of DPA (black bar) & TA (grey bar) in initial (0–108), middle (10–208) and terminal (>208) dorsiflexion.
Similarly, the anterior TA movement was also greatest in initial dorsiflexion (1.33 mm), however there also was no statistical difference among the different stages of dorsiflexion (p 0.38). As the amount of anterior DPA movement consistently increases throughout initial, middle, and terminal dorsiflexion (indicated by a lack of significance), a ratio of average DPA movement for every 108 may be created. Dividing the mean total DPA movement (3.58 mm) by the mean total dorsiflexion (24.588), gives a ratio of 1.46 mm of DPA movement for every 108 of dorsiflexion. 108 intervals were chosen as a measure that is easily monitored in theatre. 4. Discussion The principle objective of the present investigation was to identify how increasing levels of dorsiflexion affected the size of the AWA in the ankle. All specimens showed that increasing dorsiflexion caused anterior movement of both the DPA and TA away from the ankle joint. The AWA, defined as the area between the articular surface and the anterior neurovascular bundle, can therefore be seen to increase upon increasing dorsiflexion.
The present investigation concludes that during ankle arthroscopy, the position of dorsiflexion puts the dorsalis pedis artery at a lower risk of iatrogenic damage compared to plantarflexion. This is due to the anterior movement of the neurovascular bundle away from the ankle joint during dorsiflexion (1.46 mm for 108 of dorsiflexion) therefore increasing the anterior working area at dorsiflexion. The visible movement of the tibialis anterior tendon also correlates with the DPA movement at a ratio of 1:1.23 mm. Conflict of interest None declared. Acknowledgements We would like to thank St. George’s University of London’s anatomy department and their staff for the use of their facilities in the anatomy lab, including organising and preparing phenol solution embalmed cadaveric specimens in accordance with the Human Tissue Act 2004 for this research. References [1] Matava M, Sethi N, Totty W. Proximity of the posterior cruciate ligament insertion to the popliteal artery as a function of the knee flexion angle. Journal of Arthroscopic and Related Surgery 2000;16(8):796–804. [2] Fong D, Hong Y, Chan LK, Yung PSH, Chan KM. A Systematic Review on Ankle Injury and Ankle Sprain in Sports. Sports Med 2007;37(1):73–94.
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[3] Leeuw P, van Sterkenburg M, van Dijk C. arthroscopy and endoscopy of the ankle and hindfoot. Sports Medicine and Arthroscopy Review 2009;17(3):175–84. [4] Burman M. Arthroscopy or the direct visualization of joints: an experimental cadaveric study. Journal of Bone and Joint Surgery 1931;13:669–95. [5] Watanabe M. Selfoc-arthroscope (Watanabe arthroscope). Monograph 1972;24. [6] Chen YC. Clinical and cadaver studies on the ankle joint arthroscopy. Journal of the Japanese Orthopaedic Association 1976;50:63–71. [7] Strobel M. Manual of Arthroscopic Surgery. London: Springer; 2008. [8] Ferkel R, Small H, Gittins J. Complications in foot and ankle arthroscopy. Clinical Orthopaedics and Related Research 2001;393:89–104. [9] Navadgi B, Shah N, Jeer P, Rajan S. Rupture of the extensor hallucis longus tendon after ankle arthroscopy—An unusual complication. Foot and Ankle Surgery 2007;13:45–7. [10] van Dijk C, van Bergen C. Advancements in ankle arthroscopy. Journal of the American Academy of Orthopaedic Surgeons 2008;16(11):635–46. [11] Jacobs E, Groot D, Das M, Hermus J. Pseudoaneurysm of the Anterior Tibial Artery after Ankle Arthroscopy. The Journal of Foot & Ankle Surgery 2011;1–3.
[12] Basarir K, Esmer A, Tuccar E, Binnet M, Guclu B. Medial and Lateral Malleolar Arteries in Ankle Arthroscopy: A Cadaver Study. Journal of Foot & Ankle Surgery 2007;1–4. [13] van Dijk C, Scholte D. Arthroscopy of the ankle joint. Journal of Arthroscopic and Related Surgery 1997;13(1):90–6. [14] de Leeuw P, van Dijk C. Fixed distraction is not necessary for anterior ankle arthroscopy. Knee Surgery Sports Traumatology Arthroscopy 2009;17:1399– 400. [15] de Leeuw P, Golano P, Clavero J, van Dijk N. Anterior ankle arthroscopy, distraction or dorsiflexion? Surgery Sports Traumatology Arthroscopy 2010;18:594–600. [16] Shiomi J, Takahasi T, Imazato S, Yamamoto H. Flexion of the Knee Increases the Distance between the Popliteal Artery and the Proximal Tibia. Acta Orthop Scand 2001;72(6):626–8. [17] Barton D, Davies D, Mahadevan V, Dennis L, Adib T, Mudan S, et al. Dissection of soft-preserved cadavers in the training of gynaecological oncologists: report of the first UK workshop. Gynecologic Oncology 2009;113:352–6. [18] Stufkens S, de Leeuw P, van Dijk C. Is there still a place for diagnostic ankle arthroscopy? European Musculoskeletal Review 2009;90–4.
Contents lists available at ScienceDirect
Foot and Ankle Surgery journal homepage: www.elsevier.com/locate/fas
Ankle position affects dorsalis pedis artery exposure in anterior ankle arthroscopy Priyesh Ashok Karia BSc – Basic Medical Sciences with Anatomya,*, Yogesh Nathdwarawala MBBS, MS (Orth), MSc (Orth.Eng.), (FRCS Orth.)b,1, Matthew Szarko Ph.D.c,2 a
Division of Biomedical Sciences, St. George’s University of London, Cranmer Terrace, London SW17 0RE, United Kingdom Nevill Hall Hospital, Brecon Road, Abergavenny NP7 7EG, United Kingdom c Division of Biomedical Sciences, St. George’s University of London, Rm 0130, Jenner Wing Basement, Cranmer Terrace, London SW17 0RE, United Kingdom b
A R T I C L E I N F O
A B S T R A C T
Article history: Received 27 July 2013 Received in revised form 11 November 2013 Accepted 15 November 2013
Background: In anterior ankle arthroscopy, the anterior working area (AWA) is restricted by the presence of the dorsalis pedis artery (DPA) and tendons. Pseudoaneurysms caused by iatrogenic damage to the DPA are difficult to identify intraoperatively. In knee arthroscopy, risk of popliteal artery damage is reduced in the flexed position [1]. This study investigates how DPA movement is affected by dorsiflexion and plantarflexion with the aim of identifying the positions providing the greatest AWA. Methods: Twelve cadaveric ankles were dissected to access the DPA. While distracted, ankles were progressively dorsiflexed at 58 intervals from maximum plantarflexion. DPA and tibialis anterior tendon (TA) movement at each 58 interval was measured by their respective distances from the inferior border of the medial malleolus. Results: Mean ankle dorsiflexion was 24.58 1.308 with all specimens showing anterior DPA and TA movement as dorsiflexion increased. Mean DPA and TA movement at maximum dorsiflexion was 3.58 0.29 mm and 2.92 0.34 mm respectively. A ratio of 1:1.23 relates TA and DPA movement (in mm), and a ratio of 10:1.46 relates dorsiflexion angle to DPA movement (in mm). Conclusion: Anterior movement of the dorsalis pedis artery during dorsiflexion increases the AWA for anterior arthroscopy. Increasing the AWA with maximal dorsiflexion may prove to be a valuable method for lowering the risk of iatrogenic DPA damage. Additionally, increased AWA may allow the use of larger diameter surgical instruments allowing greater control and a reduction in operation time. ß 2013 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
Keywords: Ankle arthroscopy Dorsalis pedis artery
1. Introduction Ankle injuries are a common complaint and form the primary site of injury in more than 30% of all sports [2]. Conditions including chronic ankle instability, anterior ankle impingement syndrome, osteochondral lesions and osteophyte formation often require arthroscopic intervention when conservative management has failed [3]. Additionally, ankle arthroscopy can be indicated to identify the underlying cause of undiagnosed ankle pain as well as treating the cause during the procedure [3]. The ankle was initially thought to be an unsuitable joint for arthroscopy due to the narrow joint space that reduces the anterior
* Corresponding author. E-mail addresses: [email protected] (P.A. Karia), [email protected] (Y. Nathdwarawala), [email protected] (M. Szarko). 1 Tel: +44 7961482498. 2 Tel.: +44 020 8725 2831; fax: +44 020 8725 3326.
working area (AWA) and places the surrounding tendinous and vascular anatomical structures at risk of intraoperative damage [4]. The development of fibre optic arthroscopes has allowed ankle arthroscopies to be conducted when the ankle is placed in a distracted position that increases the joint space by pulling the foot away from the lower leg [5,6]. In anterior ankle arthroscopies, the AWA is particularly important as it allows space for the manoeuvring of surgical instruments and the arthroscope itself. However, the AWA is limited by anatomical structures crossing anterior to the ankle joint. These include the tendons of the anterior compartment muscles of the leg and the anterior neurovascular bundle, consisting of the dorsalis pedis artery (DPA), its bilateral deep veins and the deep fibular nerve. Access to the AWA in ankle arthroscopies are typically through anteromedial (medial to tibialis anterior tendon) and anterolateral (lateral to extensor digitorum longus tendon) portals [7]. Incorrect portal placement and limited AWA can increase the risk of intraoperative injury to tendons, vasculature, and nerves [8,9]. Complication rates after
1268-7731/$ – see front matter ß 2013 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.fas.2013.11.004
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P.A. Karia et al. / Foot and Ankle Surgery 20 (2014) 67–70
anterior ankle arthroscopy range between 3.4% and 9% [8,10]. Due to its close relationship to the anterior joint capsule, the DPA is the most affected neurovascular structure [11]. Damage to the DPA is difficult to assess intraoperatively due the maintenance of a bloodless joint through use of a thigh tourniquet [8]. Undiagnosed injury to the DPA may cause complications such as pseudoaneurysms which are more likely to rupture than typical aneurysms and if left untreated can lead to haemarthrosis and compartment syndrome [11]. Vascular complications can also occur during portal placement where branches of the dorsalis pedis artery give off smaller malleolar arteries [12]. Numerous studies have investigated ways to increase the AWA in an attempt to identify procedures for limiting intraoperative damage during anterior ankle arthroscopies. Distraction techniques tighten the anterior joint capsule by pulling the foot away from the lower leg. These techniques are used as they enhance the ability for pathology identification but, as they do not increase the AWA, they do not necessarily aid pathology treatment [13]. Dorsiflexion of the ankle has been found to increase the AWA and allow easier removal of loose bodies [13]. Forced plantarflexion creates traction that tightens the anterior ankle joint capsule and results in a reduced AWA [14]. A limited study using computed tomography (CT) found that the DPA was moved further from the ankle joint in dorsiflexion when compared to distraction [15]. A cadaveric and an MRI study looked at the position of the popliteal artery at different angles of knee flexion in knee arthroscopic procedures to determine the safest position [1,16]. Both studies that showed that the distance between the popliteal artery and the knee joint was greatest at knee flexion [1,16]. The present study combines distraction and dorsiflexion in an attempt to quantify the changes in AWA size when dorsiflexion is maximised. Additionally, in order to increase the intraoperative practicality of distraction and dorsiflexion, the anterior movement of the DPA is correlated to the anterior movement of the tibialis anterior tendon, which can be easily identified and measured during arthroscopy.
Fig. 1. Image illustrating the inferior border of the medial malleolus (IBMM) used as the fixed reference point of the ankle joint.
One end of a goniometer (Jamar, UK) was aligned immobile with the dissected posterior border of the tibial shaft and the other end aligned with the medial border of the base of the first metatarsal to measure the degree of ankle flexion and extension. The centre of the goniometer was pivoted next to the medial malleolus leaving a mobile distal end to measure the degree of ankle movement. As a beginning reference point, each ankle was distracted and then positioned in maximal plantarflexion. Ankles were then dorsiflexed at 58 intervals until maximum dorsiflexion was reached. Calliper measurements were taken between the shortest distance of the DPA and tibialis anterior tendon from the fixed reference point (IBMM) at each 58 interval. 2.3. Statistical analysis A One way analysis of variance (ANOVA) with Tukey post hoc analysis was conducted using a significance level of p 0.05. All statistical analysis was conducted using JMP 10 (USA). 2.4. Ethics
2. Materials and methods 2.1. Specimens Twelve ankles (7 left and 5 right, 8 female and 4 male) from seven soft-preserved cadavers were used in this study. The cadaveric specimens were preserved using a mixture of phenol, methylated spirits, water and glycerol in order to allow ranges of movements similar to those found in vivo [17]. 2.2. Experimental procedure The lower leg of each specimen proximal to the ankle was elevated onto a block to allow a full range of ankle motion while the specimen was placed supine on a table. The Zimmer distractor technique was adopted using cotton string that circled the leg above the talocrural joint and looped in a figure-8 distal to the midtarsal joint [15]. Thus the mid-tarsal joint was placed in a closedpacked position negating excessive movement. After distraction, the end of the string was attached to the end of the specimen table to ensure continued distraction throughout the experiment and maintain uniform distraction with all the specimens. The inferior border of the medial malleolus (IBMM) was dissected and used as a non-moveable fixed point (Fig. 1) for measurements of DPA and undissected tibialis anterior tendon (TA) movements with dorsiflexion.
All cadaveric material was donated and used in accordance with the 2004 Human Tissue Act. 3. Results Average dorsiflexion was found to be 24.58 1.308 among the twelve ankle specimens. All specimens showed anterior movement of the DPA and TA from the IBMM during dorsiflexion. The DPA showed a mean anterior movement of 3.58 0.29 mm from the IBMM during the full range of mean dorsiflexion (0–24.588). The TA achieved a mean anterior movement of 2.92 0.34 mm during the full range of dorsiflexion (0–24.588). The anterior DPA movement during dorsiflexion indicates an increase in the AWA as arterial movement away from the joint increases the area available for anterior arthroscopic procedures without risking neurovascular damage. The anterior movement of both the DPA and TA can be related to each other using a 1.23:1 ratio (mm) during dorsiflexion (Fig. 2). This ratio indicates every 1 mm of anterior TA movement is related to 1.2 mm anterior DPA movement. Measurement of anterior TA movement is easily achieved in theatre and may provide a simple method to assess increases in the AWA. Anterior DPA movement was compared among initial dorsiflexion (0–108), middle dorsiflexion (10–208), and terminal dorsiflexion (>208) (Fig. 3). Anterior DPA movement was greatest in initial dorsiflexion (1.67 mm), however no statistical difference was seen among the three stages of dorsiflexion (p 0.11).
P.A. Karia et al. / Foot and Ankle Surgery 20 (2014) 67–70
Fig. 2. The graph illustrates the association between mean DPA (&) and TA (*) movement over the full range of dorsiflexion.
69
The DPA is not visible during ankle arthroscopy and therefore it is important for the surgeon to be able to accurately predict the DPA movement upon dorsiflexion of the ankle in an attempt to gauge the size of the AWA. The present investigation has related anterior DPA movement to both anterior TA movement and increasing levels of dorsiflexion. Both anterior TA movement and ankle dorsiflexion are easily assessed in theatre and may be used to give a deeper understanding of the size of the AWA during ankle arthroscopy. Utilising a ratio of 1.23:1 allows surgeons to accurately identify anterior DPA movement based on anterior TA movement. Using this ratio, a surgeon can discern that the DPA will move anteriorly 1.23 mm for each 1 mm of anterior TA movement. Additionally, as all stages of dorsiflexion (initial, middle, and terminal) produce consistent anterior DPA movement, a 108:1.46 mm ratio can be used to identify increased AWA with dorsiflexion. Thus, using a simple goniometer, a surgeon may identify 1.46 mm of anterior DPA movement every 108 of dorsiflexion achieved. The present study has shown maximal dorsiflexion increases the space between the ankle joint and the neurovascular bundle associated with the dorsalis pedis artery. It is therefore in the best interest of the patient and surgeon for the ankle to be maximally dorsiflexed to achieve the greatest AWA. The surgeon may confirm this by measuring either tibialis anterior tendon movement or amount of ankle dorsiflexion. Increased AWA allows the introduction of a larger diameter arthroscope, allowing larger flow of saline into the joint space [18]. The greater field of view of the joint space with a large diameter arthroscope could also help reduce operation time by speeding up diagnosis and treatment [18]. The limited availability of soft-preserved cadavers confines this study to use specimens from the elderly population, therefore not reflecting the age of the patient population undergoing ankle arthroscopy. However, younger cadavers are more likely to have musculoskeletal pathology, which would affect this study. 5. Conclusion
Fig. 3. Mean movement and standard error of DPA (black bar) & TA (grey bar) in initial (0–108), middle (10–208) and terminal (>208) dorsiflexion.
Similarly, the anterior TA movement was also greatest in initial dorsiflexion (1.33 mm), however there also was no statistical difference among the different stages of dorsiflexion (p 0.38). As the amount of anterior DPA movement consistently increases throughout initial, middle, and terminal dorsiflexion (indicated by a lack of significance), a ratio of average DPA movement for every 108 may be created. Dividing the mean total DPA movement (3.58 mm) by the mean total dorsiflexion (24.588), gives a ratio of 1.46 mm of DPA movement for every 108 of dorsiflexion. 108 intervals were chosen as a measure that is easily monitored in theatre. 4. Discussion The principle objective of the present investigation was to identify how increasing levels of dorsiflexion affected the size of the AWA in the ankle. All specimens showed that increasing dorsiflexion caused anterior movement of both the DPA and TA away from the ankle joint. The AWA, defined as the area between the articular surface and the anterior neurovascular bundle, can therefore be seen to increase upon increasing dorsiflexion.
The present investigation concludes that during ankle arthroscopy, the position of dorsiflexion puts the dorsalis pedis artery at a lower risk of iatrogenic damage compared to plantarflexion. This is due to the anterior movement of the neurovascular bundle away from the ankle joint during dorsiflexion (1.46 mm for 108 of dorsiflexion) therefore increasing the anterior working area at dorsiflexion. The visible movement of the tibialis anterior tendon also correlates with the DPA movement at a ratio of 1:1.23 mm. Conflict of interest None declared. Acknowledgements We would like to thank St. George’s University of London’s anatomy department and their staff for the use of their facilities in the anatomy lab, including organising and preparing phenol solution embalmed cadaveric specimens in accordance with the Human Tissue Act 2004 for this research. References [1] Matava M, Sethi N, Totty W. Proximity of the posterior cruciate ligament insertion to the popliteal artery as a function of the knee flexion angle. Journal of Arthroscopic and Related Surgery 2000;16(8):796–804. [2] Fong D, Hong Y, Chan LK, Yung PSH, Chan KM. A Systematic Review on Ankle Injury and Ankle Sprain in Sports. Sports Med 2007;37(1):73–94.
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[3] Leeuw P, van Sterkenburg M, van Dijk C. arthroscopy and endoscopy of the ankle and hindfoot. Sports Medicine and Arthroscopy Review 2009;17(3):175–84. [4] Burman M. Arthroscopy or the direct visualization of joints: an experimental cadaveric study. Journal of Bone and Joint Surgery 1931;13:669–95. [5] Watanabe M. Selfoc-arthroscope (Watanabe arthroscope). Monograph 1972;24. [6] Chen YC. Clinical and cadaver studies on the ankle joint arthroscopy. Journal of the Japanese Orthopaedic Association 1976;50:63–71. [7] Strobel M. Manual of Arthroscopic Surgery. London: Springer; 2008. [8] Ferkel R, Small H, Gittins J. Complications in foot and ankle arthroscopy. Clinical Orthopaedics and Related Research 2001;393:89–104. [9] Navadgi B, Shah N, Jeer P, Rajan S. Rupture of the extensor hallucis longus tendon after ankle arthroscopy—An unusual complication. Foot and Ankle Surgery 2007;13:45–7. [10] van Dijk C, van Bergen C. Advancements in ankle arthroscopy. Journal of the American Academy of Orthopaedic Surgeons 2008;16(11):635–46. [11] Jacobs E, Groot D, Das M, Hermus J. Pseudoaneurysm of the Anterior Tibial Artery after Ankle Arthroscopy. The Journal of Foot & Ankle Surgery 2011;1–3.
[12] Basarir K, Esmer A, Tuccar E, Binnet M, Guclu B. Medial and Lateral Malleolar Arteries in Ankle Arthroscopy: A Cadaver Study. Journal of Foot & Ankle Surgery 2007;1–4. [13] van Dijk C, Scholte D. Arthroscopy of the ankle joint. Journal of Arthroscopic and Related Surgery 1997;13(1):90–6. [14] de Leeuw P, van Dijk C. Fixed distraction is not necessary for anterior ankle arthroscopy. Knee Surgery Sports Traumatology Arthroscopy 2009;17:1399– 400. [15] de Leeuw P, Golano P, Clavero J, van Dijk N. Anterior ankle arthroscopy, distraction or dorsiflexion? Surgery Sports Traumatology Arthroscopy 2010;18:594–600. [16] Shiomi J, Takahasi T, Imazato S, Yamamoto H. Flexion of the Knee Increases the Distance between the Popliteal Artery and the Proximal Tibia. Acta Orthop Scand 2001;72(6):626–8. [17] Barton D, Davies D, Mahadevan V, Dennis L, Adib T, Mudan S, et al. Dissection of soft-preserved cadavers in the training of gynaecological oncologists: report of the first UK workshop. Gynecologic Oncology 2009;113:352–6. [18] Stufkens S, de Leeuw P, van Dijk C. Is there still a place for diagnostic ankle arthroscopy? European Musculoskeletal Review 2009;90–4.
