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First Tarsometatarsal Arthrodesis: An Anatomic Evaluation of Dorsomedial Versus Plantar Plating
The Journal of Foot & Ankle Surgery 54 (2015) 787–792
Contents lists available at ScienceDirect
The Journal of Foot & Ankle Surgery journal homepage: www.jfas.org
First Tarsometatarsal Arthrodesis: An Anatomic Evaluation of Dorsomedial Versus Plantar Plating € ber, Dr med 2, Clemens Loracher, Dr med 3, Paul Simons, Dr med 1, Rosemarie Fro Matthias Knobe, PD Dr med habil 4, Florian Gras, PD Dr med habil 3, Gunther O. Hofmann, Prof Dr med Dr rer nat 3, Kajetan Klos, PD Dr med habil 1 1
Foot and Ankle Surgery, Katholisches Klinikum Mainz, Mainz, Germany Department of Anatomy 1, Friedrich Schiller University, Jena, Germany Department of Trauma, Hand and Reconstructive Surgery, Friedrich-Schiller-University Jena, Jena, Germany 4 Foot and Ankle Surgery, Department of Trauma and Reconstructive Surgery, University Aachen, Aachen, Germany 2 3
a r t i c l e i n f o
a b s t r a c t
Level of Clinical Evidence: 5
Fusion of the first tarsometatarsal joint is a widely used procedure for the correction of hallux valgus deformity. Although dorsomedial H-shaped plating systems are being increasingly used, fusion can also be achieved by plantar plating. The goal of the present study was to compare these 2 operative techniques based on the anatomic considerations and show the potential pitfalls of both procedures. Six pairs of deep-frozen human lower legs were used in the present cadaveric study. In a randomized manner, either dorsomedial arthrodesis or plantar plating through a medial incision was performed. With regard to arterial injury, the plantar technique resulted in fewer lesions (plantar, 4 injuries [66.7%] to the terminal branches of the first digital branch of the medial plantar artery; dorsomedial, 3 injuries [50%] to the main trunks of the plantar metatarsal arteries and the first dorsal metatarsal artery). With respect to injury to the veins, the plantar procedure affected significantly fewer high-caliber subcutaneous trunk veins. The nerves coursing through the operative field, such as the saphenous and superficial fibular nerves, were compromised more often by the dorsal approach. Neither the plantar plating nor the dorsomedial plating technique was associated with injury to the insertion of the tibialis anterior muscle. Both studied techniques are safe, well-established procedures. Arthrodesis with plantar plating, however, offers additional advantages and is a reliable tool in the foot and ankle surgeon’s repertoire. Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved.
Keywords: first tarsometatarsal joint hallux valgus surgery internal fixation Lapidus arthrodesis
Fusion of the first tarsometatarsal (TMT) joint is a widely used procedure for the correction of hallux valgus deformity associated with instability of the first TMT (1). Fixation techniques using 2 or 3 screws were mainly applied for correction early on; however, these procedures were associated with implant failure rates of 4.5% and nonunion rates of 15% (2,3). Plate osteosynthesis has gained popularity in recent years. Initially, dorsomedial H-shaped plating systems were used (4,5). The biomechanical advantages of these systems, however, have not been established (6,7); therefore, nonweightbearing for 4 to 8 weeks postoperative is recommended. Over time, medial plating was complemented by plantar plating
Financial Disclosure: This study was partially funded by a grant from the German Society of Foot and Ankle Surgery. Conflict of Interest: Paul Simons serves as a technical expert for Synthes and AAA and as a funded investigator for Wright Medical; Florian Gras serves as a technical expert for Stryker. Address correspondence to: Paul Simons, Dr med, Department of Foot and Ankle Surgery, Katholisches Klinikum Mainz, An der Goldgrube 11, Mainz 55131, Germany. E-mail address: [email protected] (P. Simons).
techniques, providing more biomechanical stability (8–10). The initial clinical results of plantar plating were very promising (11–13). Owing to the altered positioning of the plate, however, dissection is affected, requiring the incision to be made substantially more plantarly. Dissection proceeds in the direction of the tibialis anterior tendon. In part, the plate is positioned in the region of the abductor hallucis muscle. The first TMT joint is exposed at the medial aspect, where it will be more visible than with dorsal dissection, and defined by the second ray, among other structures, at the lateral aspect. The goal of the present study was to compare 2 first TMT joint arthrodesis techniques on cadaveric specimens and to identify the anatomic structures at particular risk of injury. We hypothesized that although the 2 techniques would differ in terms of their injury profile, they will be comparably safe. Materials and Methods Six pairs of deep-frozen human lower legs were used in the present cadaveric study. The mean age of the cadaveric donors was 78.8 (range 71 to 88) years. Four of the pairs of lower legs originated from female donors. The specimens showed no signs of
1067-2516/$ - see front matter Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2014.12.028
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Fig. 2. Exposure of the first tarsometatarsal joint (arrow) using a plantar approach.
Fig. 1. (A and B) The course of the incision used in joint fusion with plantar plating at the transition to the plantar skin. The first metatarsal and medial cuneiform bone were marked before the procedure. previous trauma or other pathologic conditions. Written consent for the use of cadaveric donors for medical research and academic purposes was provided. The ethics committee approved the present human cadaveric study. For the access route to the first TMT joint, 1 lower leg of a pair was randomly selected to undergo a medial incision, and the other member of the pair was subjected to a dorsomedial approach to the TMT joint. An experienced foot and ankle surgeon performed all the surgeries. Arthrodesis With Plantar Plating We adopted the operative technique previously described by Walther et al (13). An incision was made medially at the transition from the plantar to the dorsal skin. The incision coursed from the proximal end of the medial cuneiform along the superior border of the abductor hallucis muscle as far as the base of the hallux proximal phalanx (Fig. 1). Taking great care to not injure the neurovascular structures, the first metatarsal shaft and the first TMT joint were then exposed. Next, blunt dissection through the connective tissue layer between the abductor hallucis muscle and the bone and blunt release of the plantar structures from the capsule of the first TMT joint were performed to prepare the site for later plate implantation. Using a retractor, the abductor hallucis muscle was retracted in the plantar direction, and the neurovascular bundle was retracted dorsally. The insertion of the tibialis anterior muscle was measured on both the medial cuneiform and the first metatarsal. The joint capsule was opened along the joint space, severing the part of the insertion of the tibialis anterior muscle originating from the metatarsal (Fig. 2). Subsequently, the joint surfaces were delicately removed using an oscillating saw (LEXAÒ System, Wright Medical Deutschland GmbH, Raisting, Germany). Next, traction screws were implanted (Wright Medical Deutschland GmbH) using a Kirschner wire that was brought in from the dorsal-distal to the plantar-proximal aspect, approximately 1.5 cm from the joint space. As a final step, a precast plantar plate was implanted according to the manufacturer’s instructions (DARCOÒ Plantar Lapidus Plate; Wright Medical Deutschland GmbH; Fig. 3). Intraoperative fluoroscopy was used to review the positioning of the implants.
hallux proximal phalanx (Fig. 4). Taking care not to injure any anatomic structures, we dissected through the subcutaneous tissue. The fascia and extensions of the extensor retinaculum were cut medially to the tendon of the extensor hallucis longus muscle. Subsequently, the first metatarsal was exposed as far as the shaft, and the first TMT joint was exposed as far as the medial aspect of the insertion of the tibialis anterior muscle just periosteally. The first TMT joint was again exposed from the proximal aspect of the insertion of the tibialis posterior muscle as far as the lateral border of the medial cuneiform bone (Fig. 4). The joint surfaces were dissected with an oscillating saw, in the same manner as in the plantar approach. As the first step in the preparation for arthrodesis, a 4-mm partially threaded cannulated screw (Wright Medical Deutschland GmbH) was introduced just as for plantar plating. Next, a locking H-plate (DARCOÒ LPSÔ Locked Lapidus Plate; Wright Medical Deutschland GmbH) was implanted dorsomedially over the joint according to the manufacturer’s instructions (Fig. 5). Intraoperative fluoroscopy confirmed the correct placement and fixation of the screws and plate. As the final step, the anatomic structures at risk were dissected, and their injury profile was documented.
Results The arteries, veins, and nerves that were injured during the operative procedures are listed in Tables 1, 2, and 3, respectively. Injuries to the second metatarsal were not recorded. In terms of the arterial injury profile, the plantar technique caused fewer lesions. The plantar technique was associated with 4 injuries (66.7%) to the terminal branches of the first digital branch of the medial plantar artery. However, the main trunks of the plantar metatarsal arteries and the first dorsal metatarsal artery were injured only with the dorsomedial approach. In contrast, the dorsalis pedis artery and its arcuate artery branch and the lateral tarsal artery
Arthrodesis With Dorsomedial Plating The technique by Fuhrmann (5) was adopted in the present study. The incision coursed dorsomedially from the medial cuneiform across the first TMT joint, medially to the tendon of the extensor hallucis longus muscle, and ended at the base of the
Fig. 3. Plantar approach to the first tarsometatarsal joint with plantar plating.
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Table 1 Arteries injured during surgery Artery
Plantar Approach (n ¼ 6)
Dorsal Approach (n ¼ 6)
Dorsalis pedis artery Lateral tarsal artery Arcuate artery First plantar metatarsal artery First dorsal metatarsal artery First digital branch of medial plantar artery
0 0 0 0 0 4/6 (66.7%), terminal branches severed
0 0 0 2/6 (33.3%), main stem severed 1/6 (16.7%), main stem severed Not in operative field
Discussion
Fig. 4. Exposure of the first tarsometatarsal joint (arrow) using a dorsomedial approach.
remained intact with both the plantar and the dorsal plating procedures (Table 1). In terms of the venous injury profile, both methods were associated with injuries to the superficial and deep venous systems (Table 2, Figs. 6 and 7). The plantar approach, however, was associated with significantly fewer injuries to large-caliber subcutaneous trunk veins. One injury (16.7%) occurred to the tributaries of the dorsal venous arch of the foot coming from the plantar aspect and two (33.3%) occurred to the main trunks of the dorsalis pedis veins. In 1 studied specimen (16.7%) in which the dorsal approach was applied, superficial venous drainage was accomplished solely by way of the great saphenous vein. The dorsal venous arch of the foot was missing in this specimen. Another specimen (16.7 %) in this study group was missing the dorsalis pedis veins. The dorsomedial approach was associated with more severe damage to the nerves coursing through the operative field. The saphenous nerve was less often affected. In 3 specimens (50%) treated with the dorsal approach, however, the saphenous nerve did not cross the operative field (Table 3). Likewise, the plantar approach posed less risk to the superficial fibular nerve (Figs. 6 and 7). The deep fibular nerve remained intact in both study groups. In addition, the medial plantar nerve remained intact in the plantar surgery cases. The distribution of tendon insertion of the tibialis anterior muscle into the medial cuneiform and the first metatarsal is presented in Table 4. Neither plantar nor dorsomedial plating resulted in any injury to the insertion of the tibialis anterior muscle (Figs. 8 and 9). In 2 cases of dorsal plating (33.3%), a small portion of the tibialis anterior tendon was engaged by the plate (Fig. 9).
In elective foot and ankle surgery, advances in implant techniques play an important role in promoting patient safety by reducing the incidence of complications and in increasing patient satisfaction by enabling early transition to full weightbearing and facilitating cosmetically superior results. Plantar plating for first TMT arthrodesis was developed with these goals in mind (10,11,13). The objective of the present study was to compare the advantages and disadvantages between the plantar operative technique and the standard procedure of fusion with dorsomedial plating. The present study also aimed to identify the anatomic structures at risk during each operative technique. To the best of our knowledge, the present study is the first anatomic on this topic. The findings supported our hypothesis that despite the differences in their injury profile, the 2 techniques are comparably safe, although the medial approach displayed certain advantages. The overall incidence of injury to arteries was low in both study groups. The medial approach disrupted the terminal vessels of the arterial system supplying the medial aspect of the first ray to a small extent. The relevant first digital branch of the medial plantar artery is a relatively small-caliber vessel. Given the extensive compensatory potential of the circulatory system (14) and that only the terminal branches of the vessels were affected, it is reasonable to assume that the relatively stronger first plantar metatarsal artery and first dorsal metatarsal artery will maintain an adequate blood supply of the first metatarsal and that of the proximal and distal phalanges (15). A greater issue is injury to the first plantar metatarsal artery (2 of 6 [33.3%] were injured) and the first dorsal metatarsal artery (1 of 6 [16.7%] injured) associated with the dorsomedial approach. In particular, when both arteries were injured at the same time, the relatively small-caliber first digital branch of the medial plantar artery must take over the supply. This carries a risk of impaired perfusion of the first TMT joint and the first ray. In addition, arterial injury can lead to postoperative bleeding, requiring subsequent revision, or result in hematoma formation and increased secondary infection rates, reducing patient satisfaction. From our findings, the medial plating was superior with regard to arterial considerations. Analysis of the venous injuries revealed substantially more pronounced anatomic variability than that of other structures. In 1 (1.17%) dorsal plating specimen, superficial venous drainage was achieved
Table 2 Veins injured during surgery Vein
Plantar Approach (n ¼ 6)
Dorsal Approach (n ¼ 6)
Great saphenous vein
6/6 (100%), tributaries severed 1/6 (16.7%), tributaries severed 2/5 (40%), main trunk severed
1/6 (16.7%), tributaries severed; 5/6 (83.3%), main trunk severed 2/5 (40%), tributaries severed; 2/5 (40%), main trunk severed 1/5 (20%), main trunk severed
Dorsal venous arch of foot Dorsalis pedis veins Fig. 5. Dorsomedial first tarsometatarsal joint arthrodesis using an H-plate.
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Table 3 Nerves injured during surgery Nerve
Plantar Approach (n ¼ 6)
Dorsal Approach (n ¼ 6)
Saphenous nerve Superficial fibular nerve
0 3/6 (50%), terminal branches severed1/6 (16.7%) main stem severed 0 0
1/3 (33%), main stem severed 3/6 (50%), terminal branches severed2/6 (33.3%), main stem severed 0 Not in operative field
Deep fibular nerve Medial plantar nerve
solely by the great saphenous vein. In another case of fusion with plantar plating, the dorsalis pedis veins were missing. In all specimens implanted with a plantar plate, the branches of the greater saphenous vein coursing from the medial aspect across the first TMT joint were severed (Fig. 6). To a lesser extent, this injury pattern also continued in the tributaries of the dorsal venous arch of the foot coming from the plantar aspect. Because the access is approximately at the level of the watershed between the plantar and dorsal venous outflow, drainage should be not be an issue. In contrast, the dorsomedial incision led to significantly more frequent injury to the main trunks, a plausible injury pattern given the typical vessel course across the operative field (16). Both methods were associated with a risk to the dorsalis pedis veins, running close to the lateral border of the TMT joint. Arthrodesis with plantar plating was associated with injury, mainly owing to implantation of compression screws. If compression screws were also implanted from the plantar aspect, the risk could be reduced further. A trend toward more favorable results with plantar plating was also recorded during evaluation of the surgery-related injury to the nerves. The dorsal approach was associated with a significantly greater risk of injury to the distal segments of the saphenous nerve. In contrast, plantar plating allowed this nerve to remain fully intact. In addition, previous studies reported an increased risk of injury to the branches of the superficial fibular nerve caused by a dorsal incision, favoring the plantar access route (17). Our findings have corroborated these results. The incidence of injury to the medial dorsal cutaneous nerve and intermediate dorsal cutaneous nerve was the same with both techniques. The cutaneous nerve and superficial fibular nerve cover a large area and hence cross both intervention territories. Such an extensive capillary distribution almost invariably lends itself to injury, in particular, during operative interventions involving the metatarsal-cuneiform and metatarsophalangeal joints and the tendon of the extensor hallucis longus muscle. Likewise, severing the superficial fibular nerve or the main trunk of the medial dorsal cutaneous
Fig. 7. Lesion profile pertaining to the great saphenous vein (circle) and the superficial fibular nerve (arrow) associated with dorsal access to the first tarsometatarsal joint.
nerve, which will be encountered more frequently with dorsal access routes, can be attributed to such branching. Injuries will manifest as postoperative scar pain in 5% of patients after hallux surgery (18) and in 45% in cases of direct injury to the medial dorsal cutaneous nerve (19). To avoid extensive nerve injury, intraoperative localization of a large-caliber anastomosis between the great saphenous vein and the dorsal venous arch of the foot approximately 2 cm proximally to the first MTP joint is recommended (16). The medial dorsal cutaneous nerve is located more deeply beneath the union of the “sentinel vein” and the dorsal venous arch (16), and caution must be used during the dorsal and plantar approach alike. For the deep fibular nerve and medial plantar nerve, no differences were recorded between the 2 methodsdthe nerve remained intact with both techniques. Because the medial plantar nerve does not appear in the dissection territory of the dorsal approach, a comparison with respect to the absence of its injury potential was inapplicable. Regarding the cosmetic results, the medial approach seems to be better, consistent with the theoretical considerations (15). The plantar approach fared better in terms of soft tissue coverage of the implants, because the plate was positioned beneath the abductor hallucis muscle (Fig. 10). This has potential positive implications regarding the infection rates. Supplementary interventions on the first ray, such as lateral release, can be easily accomplished using either approach (15,20–22). The potential advantages of the medial approach compared with the dorsomedial approach were summarized by Dayton et al (15) as follows. First, the medial approach provides good access to both sesamoid bones and, second, a superior range of motion of the metatarsophalangeal Table 4 Relative percentage of insertion of tibialis anterior muscle
Fig. 6. Lesion profile pertaining to the great saphenous vein (circle) and the superficial fibular nerve (arrow) associated with plantar access to the first tarsometatarsal joint.
Specimen No.
Insertion on Medial Cuneiform (%)
Insertion on First Metatarsal (%)
1, Right 1, Left 2, Right 2, Left 3, Right 3, Left 4, Right 4, Left 5, Right 5, Left 6, Right 6, Left Mean SD
64.3 70.0 52.9 68.4 34.5 86.2 52.4 52.2 57.1 60.0 73.7 65.2 61.4 12.6
35.7 30.0 47.1 31.6 65.5 13.8 47.6 47.8 42.9 40.0 26.3 34.8 38.6 12.6
Abbreviation: SD, standard deviation.
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Fig. 8. Insertions of the tibialis anterior muscle (circles) of 4 different specimens treated with plantar plating. (A and B) The tendon shown still attached to the insertion. (C and D) The tendon has been dissected away from the insertion. The specimen shown in (B) exhibited bipartite insertion on the medial cuneiform and base of the first metatarsal.
joint of the great toe because the dorsal structures will not be compromised. Third, in hallux valgus repair, the access is at the level of the deformity, supporting the repair. Finally, the medial approach results in a superior cosmetic appearance and good maintenance of the perfusion of the metatarsal head. The disadvantages cited by Dayton et al (15) included increased interference by hypertrophic scars, poor access to the first intermetatarsal space, and, occasionally, impeded lateral release. With respect to the latter 2 considerations, the medial approach allows for efficient lateral release (19) but also provides additional dorsal access to the first intermetatarsal space (18). Measurement of the insertion of the tibialis anterior muscle revealed that the medial cuneiform (mean 61.4%) had the largest relative share of the insertion. A mean share of 38.6% was attributed to the first metatarsal. Similar values were obtained in other studies. Thus, partially severing the tendon insertion during exposure of the first TMT joint will not increase the risk of structural instability. Caution should be used, however, because variants of normal also exist, with a predominant tendon share to the first metatarsal (23). These exceptions should be recognized intraoperatively to avoid
tendon rupture (11). Apart from 2 (2.34%) specimens treated with dorsal plating in which the muscle tendon was jammed beneath the proximal plate, no implant-related injury to the muscle insertion was recorded. Thus, dorsomedial plating requires the surgeon to exercise particular caution because the muscle tendon will be located at the site of plate implantation. In our study, the length of the incision was standardized and, similar to other anatomic studies on hallux valgus correction (24), extended the entire length of the first metatarsal with exposure of the first TMT joint. This corresponds to the standard approach used in the correction of extensive deformities (11,15). In addition, the access magnitude will thus be defined in relation to the size of the foot, allowing for comparisons between groups. We do not believe that the relatively low sample number (6 specimens per studied technique) significantly compromised the validity of our study. Although the operative interventions in our study were conducted on cadaveric specimens under optimal dissection conditions, the results adequately elucidated the potential benefits and drawbacks of the studied techniques. Hence, the present study has provided
Fig. 9. (A and B) Two examples of dorsomedial plating. The insertion of the tibialis anterior tendon (circles) remained intact. (B) The tendon was jammed under the proximal dorsal screw hole (arrow).
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Fig. 10. The arthrodesis plantar plate was largely covered by the abductor hallucis muscle (arrow). This muscle had been dissected in part and retracted with forceps.
surgeons with valuable anatomic information to guide the choice of technique, although the results should not be automatically extrapolated to daily clinical practice. Additional studies are needed before any conclusive recommendations can be given. In conclusion, both of the studied operative techniques were shown to be safe, well-established first TMT arthrodesis procedures. Arthrodesis with plantar plating offers specific advantages such as a more favorable access site morbidity profile and is thus an additional reliable tool in the foot and ankle surgeon’s repertoire. References 1. Rutherford RL. The Lapidus procedure for primus metatarsus adductus. J Am Podiatry Assoc 64:581–584, 1974.
2. Sangeorzan BJ, Hansen ST Jr. Modified Lapidus procedure for hallux valgus. Foot Ankle 9:262–266, 1989. 3. Myerson M, Allon S, McGarvey W. Metatarsocuneiform arthrodesis for management of hallux valgus and metatarsus primus varus. Foot Ankle 13:107–115, 1992. 4. Saxena A, Nguyen A, Nelsen E. Lapidus bunionectomy: early evaluation of crossed lag screws versus locking plate with plantar lag screw. J Foot Ankle Surg 48:170– 179, 2009. 5. Fuhrmann RA. Arthrodesis of the first tarsometatarsal joint for correction of the advanced splayfoot accompanied by a hallux valgus. Oper Orthop Traumatol 17:195–210, 2005. 6. Cohen DA, Parks BG, Schon LC. Screw fixation compared to H-locking plate fixation for first metatarsocuneiform arthrodesis: a biomechanical study. Foot Ankle Int 26:984–989, 2005. 7. Gruber F, Sinkov VS, Bae SY, Parks BG, Schon LC. Crossed screws versus dorsomedial locking plate with compression screw for first metatarsocuneiform arthrodesis: a cadaver study. Foot Ankle Int 29:927–930, 2008. 8. Klos K, Gueorguiev B, Muckley T, Frober R, Hofmann GO, Schwieger K, Windolf M. Stability of medial locking plate and compression screw versus two crossed screws for Lapidus arthrodesis. Foot Ankle Int 31:158–163, 2010. 9. Scranton PE, Coetzee JC, Carreira D. Arthrodesis of the first metatarsocuneiform joint: a comparative study of fixation methods. Foot Ankle Int 30:341–345, 2009. 10. Klos K, Simons P, Hajduk AS, Hoffmeier KL, Gras F, Frober R, Hofmann GO, Muckley T. Plantar versus dorsomedial locked plating for Lapidus arthrodesis: a biomechanical comparison. Foot Ankle Int 32:1081–1085, 2011. 11. Klos K, Wilde CH, Lange A, Wagner A, Gras F, Skulev HK, Muckley T, Simons P. Modified Lapidus arthrodesis with plantar plate and compression screw for treatment of hallux valgus with hypermobility of the first ray: a preliminary report. Foot Ankle Surg 19:239–244, 2013. 12. Gutteck N, Wohlrab D, Zeh A, Radetzki F, Delank KS, Lebek S. Comparative study of Lapidus bunionectomy using different osteosynthesis methods. Foot Ankle Surg 19:218–221, 2013. 13. Walther M, Simons P, Nass K, Roser A. [Fusion of the first tarsometatarsal joint using a plantar tension band osteosynthesis]. Oper Orthop Traumatol 23:52–59, 2011. 14. Easley ME, Kelly IP. Avascular necrosis of the hallux metatarsal head. Foot Ankle Clin 5:591–608, 2000. 15. Dayton P, Glynn A, LoPiccolo J. Medial incision approach to the first metatarsophalangeal joint. J Foot Ankle Surg 40:414–417, 2001. 16. Makwana N, Hossain M, Kumar A, Mbako A. The sentinel vein: an anatomical guide to localisation of the dorsomedial cutaneous nerve in hallux surgery. J Bone Joint Surg Br 93:1373–1376, 2011. 17. Solan MC, Lemon M, Bendall SP. The surgical anatomy of the dorsomedial cutaneous nerve of the hallux. J Bone Joint Surg Br 83:250–252, 2001. 18. Meier PJ, Kenzora JE. The risks and benefits of distal first metatarsal osteotomies. Foot Ankle 6:7–17, 1985. 19. Blair JM, Botte MJ. Surgical anatomy of the superficial peroneal nerve in the ankle and foot. Clin Orthop Relat Res 305:229–238, 1994. 20. Lee WC, Kim YM. Technique tip: lateral soft-tissue release for correction of hallux valgus through a medial incision using a dorsal flap over the first metatarsal. Foot Ankle Int 28:949–951, 2007. 21. Owens S, Thordarson DB. The adductor hallucis revisited. Foot Ankle Int 22:186– 191, 2001. 22. Stamatis ED, Huber MH, Myerson MS. Transarticular distal soft-tissue release with an arthroscopic blade for hallux valgus correction. Foot Ankle Int 25:13–18, 2004. 23. Brenner E. Insertion of the tendon of the tibialis anterior muscle in feet with and without hallux valgus. Clin Anat 15:217–223, 2002. 24. Lin I, Bonar SK, Anderson RB, Davis WH. Distal soft tissue release using direct and indirect approaches: an anatomic study. Foot Ankle Int 17:458–463, 1996.
Contents lists available at ScienceDirect
The Journal of Foot & Ankle Surgery journal homepage: www.jfas.org
First Tarsometatarsal Arthrodesis: An Anatomic Evaluation of Dorsomedial Versus Plantar Plating € ber, Dr med 2, Clemens Loracher, Dr med 3, Paul Simons, Dr med 1, Rosemarie Fro Matthias Knobe, PD Dr med habil 4, Florian Gras, PD Dr med habil 3, Gunther O. Hofmann, Prof Dr med Dr rer nat 3, Kajetan Klos, PD Dr med habil 1 1
Foot and Ankle Surgery, Katholisches Klinikum Mainz, Mainz, Germany Department of Anatomy 1, Friedrich Schiller University, Jena, Germany Department of Trauma, Hand and Reconstructive Surgery, Friedrich-Schiller-University Jena, Jena, Germany 4 Foot and Ankle Surgery, Department of Trauma and Reconstructive Surgery, University Aachen, Aachen, Germany 2 3
a r t i c l e i n f o
a b s t r a c t
Level of Clinical Evidence: 5
Fusion of the first tarsometatarsal joint is a widely used procedure for the correction of hallux valgus deformity. Although dorsomedial H-shaped plating systems are being increasingly used, fusion can also be achieved by plantar plating. The goal of the present study was to compare these 2 operative techniques based on the anatomic considerations and show the potential pitfalls of both procedures. Six pairs of deep-frozen human lower legs were used in the present cadaveric study. In a randomized manner, either dorsomedial arthrodesis or plantar plating through a medial incision was performed. With regard to arterial injury, the plantar technique resulted in fewer lesions (plantar, 4 injuries [66.7%] to the terminal branches of the first digital branch of the medial plantar artery; dorsomedial, 3 injuries [50%] to the main trunks of the plantar metatarsal arteries and the first dorsal metatarsal artery). With respect to injury to the veins, the plantar procedure affected significantly fewer high-caliber subcutaneous trunk veins. The nerves coursing through the operative field, such as the saphenous and superficial fibular nerves, were compromised more often by the dorsal approach. Neither the plantar plating nor the dorsomedial plating technique was associated with injury to the insertion of the tibialis anterior muscle. Both studied techniques are safe, well-established procedures. Arthrodesis with plantar plating, however, offers additional advantages and is a reliable tool in the foot and ankle surgeon’s repertoire. Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved.
Keywords: first tarsometatarsal joint hallux valgus surgery internal fixation Lapidus arthrodesis
Fusion of the first tarsometatarsal (TMT) joint is a widely used procedure for the correction of hallux valgus deformity associated with instability of the first TMT (1). Fixation techniques using 2 or 3 screws were mainly applied for correction early on; however, these procedures were associated with implant failure rates of 4.5% and nonunion rates of 15% (2,3). Plate osteosynthesis has gained popularity in recent years. Initially, dorsomedial H-shaped plating systems were used (4,5). The biomechanical advantages of these systems, however, have not been established (6,7); therefore, nonweightbearing for 4 to 8 weeks postoperative is recommended. Over time, medial plating was complemented by plantar plating
Financial Disclosure: This study was partially funded by a grant from the German Society of Foot and Ankle Surgery. Conflict of Interest: Paul Simons serves as a technical expert for Synthes and AAA and as a funded investigator for Wright Medical; Florian Gras serves as a technical expert for Stryker. Address correspondence to: Paul Simons, Dr med, Department of Foot and Ankle Surgery, Katholisches Klinikum Mainz, An der Goldgrube 11, Mainz 55131, Germany. E-mail address: [email protected] (P. Simons).
techniques, providing more biomechanical stability (8–10). The initial clinical results of plantar plating were very promising (11–13). Owing to the altered positioning of the plate, however, dissection is affected, requiring the incision to be made substantially more plantarly. Dissection proceeds in the direction of the tibialis anterior tendon. In part, the plate is positioned in the region of the abductor hallucis muscle. The first TMT joint is exposed at the medial aspect, where it will be more visible than with dorsal dissection, and defined by the second ray, among other structures, at the lateral aspect. The goal of the present study was to compare 2 first TMT joint arthrodesis techniques on cadaveric specimens and to identify the anatomic structures at particular risk of injury. We hypothesized that although the 2 techniques would differ in terms of their injury profile, they will be comparably safe. Materials and Methods Six pairs of deep-frozen human lower legs were used in the present cadaveric study. The mean age of the cadaveric donors was 78.8 (range 71 to 88) years. Four of the pairs of lower legs originated from female donors. The specimens showed no signs of
1067-2516/$ - see front matter Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2014.12.028
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P. Simons et al. / The Journal of Foot & Ankle Surgery 54 (2015) 787–792
Fig. 2. Exposure of the first tarsometatarsal joint (arrow) using a plantar approach.
Fig. 1. (A and B) The course of the incision used in joint fusion with plantar plating at the transition to the plantar skin. The first metatarsal and medial cuneiform bone were marked before the procedure. previous trauma or other pathologic conditions. Written consent for the use of cadaveric donors for medical research and academic purposes was provided. The ethics committee approved the present human cadaveric study. For the access route to the first TMT joint, 1 lower leg of a pair was randomly selected to undergo a medial incision, and the other member of the pair was subjected to a dorsomedial approach to the TMT joint. An experienced foot and ankle surgeon performed all the surgeries. Arthrodesis With Plantar Plating We adopted the operative technique previously described by Walther et al (13). An incision was made medially at the transition from the plantar to the dorsal skin. The incision coursed from the proximal end of the medial cuneiform along the superior border of the abductor hallucis muscle as far as the base of the hallux proximal phalanx (Fig. 1). Taking great care to not injure the neurovascular structures, the first metatarsal shaft and the first TMT joint were then exposed. Next, blunt dissection through the connective tissue layer between the abductor hallucis muscle and the bone and blunt release of the plantar structures from the capsule of the first TMT joint were performed to prepare the site for later plate implantation. Using a retractor, the abductor hallucis muscle was retracted in the plantar direction, and the neurovascular bundle was retracted dorsally. The insertion of the tibialis anterior muscle was measured on both the medial cuneiform and the first metatarsal. The joint capsule was opened along the joint space, severing the part of the insertion of the tibialis anterior muscle originating from the metatarsal (Fig. 2). Subsequently, the joint surfaces were delicately removed using an oscillating saw (LEXAÒ System, Wright Medical Deutschland GmbH, Raisting, Germany). Next, traction screws were implanted (Wright Medical Deutschland GmbH) using a Kirschner wire that was brought in from the dorsal-distal to the plantar-proximal aspect, approximately 1.5 cm from the joint space. As a final step, a precast plantar plate was implanted according to the manufacturer’s instructions (DARCOÒ Plantar Lapidus Plate; Wright Medical Deutschland GmbH; Fig. 3). Intraoperative fluoroscopy was used to review the positioning of the implants.
hallux proximal phalanx (Fig. 4). Taking care not to injure any anatomic structures, we dissected through the subcutaneous tissue. The fascia and extensions of the extensor retinaculum were cut medially to the tendon of the extensor hallucis longus muscle. Subsequently, the first metatarsal was exposed as far as the shaft, and the first TMT joint was exposed as far as the medial aspect of the insertion of the tibialis anterior muscle just periosteally. The first TMT joint was again exposed from the proximal aspect of the insertion of the tibialis posterior muscle as far as the lateral border of the medial cuneiform bone (Fig. 4). The joint surfaces were dissected with an oscillating saw, in the same manner as in the plantar approach. As the first step in the preparation for arthrodesis, a 4-mm partially threaded cannulated screw (Wright Medical Deutschland GmbH) was introduced just as for plantar plating. Next, a locking H-plate (DARCOÒ LPSÔ Locked Lapidus Plate; Wright Medical Deutschland GmbH) was implanted dorsomedially over the joint according to the manufacturer’s instructions (Fig. 5). Intraoperative fluoroscopy confirmed the correct placement and fixation of the screws and plate. As the final step, the anatomic structures at risk were dissected, and their injury profile was documented.
Results The arteries, veins, and nerves that were injured during the operative procedures are listed in Tables 1, 2, and 3, respectively. Injuries to the second metatarsal were not recorded. In terms of the arterial injury profile, the plantar technique caused fewer lesions. The plantar technique was associated with 4 injuries (66.7%) to the terminal branches of the first digital branch of the medial plantar artery. However, the main trunks of the plantar metatarsal arteries and the first dorsal metatarsal artery were injured only with the dorsomedial approach. In contrast, the dorsalis pedis artery and its arcuate artery branch and the lateral tarsal artery
Arthrodesis With Dorsomedial Plating The technique by Fuhrmann (5) was adopted in the present study. The incision coursed dorsomedially from the medial cuneiform across the first TMT joint, medially to the tendon of the extensor hallucis longus muscle, and ended at the base of the
Fig. 3. Plantar approach to the first tarsometatarsal joint with plantar plating.
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Table 1 Arteries injured during surgery Artery
Plantar Approach (n ¼ 6)
Dorsal Approach (n ¼ 6)
Dorsalis pedis artery Lateral tarsal artery Arcuate artery First plantar metatarsal artery First dorsal metatarsal artery First digital branch of medial plantar artery
0 0 0 0 0 4/6 (66.7%), terminal branches severed
0 0 0 2/6 (33.3%), main stem severed 1/6 (16.7%), main stem severed Not in operative field
Discussion
Fig. 4. Exposure of the first tarsometatarsal joint (arrow) using a dorsomedial approach.
remained intact with both the plantar and the dorsal plating procedures (Table 1). In terms of the venous injury profile, both methods were associated with injuries to the superficial and deep venous systems (Table 2, Figs. 6 and 7). The plantar approach, however, was associated with significantly fewer injuries to large-caliber subcutaneous trunk veins. One injury (16.7%) occurred to the tributaries of the dorsal venous arch of the foot coming from the plantar aspect and two (33.3%) occurred to the main trunks of the dorsalis pedis veins. In 1 studied specimen (16.7%) in which the dorsal approach was applied, superficial venous drainage was accomplished solely by way of the great saphenous vein. The dorsal venous arch of the foot was missing in this specimen. Another specimen (16.7 %) in this study group was missing the dorsalis pedis veins. The dorsomedial approach was associated with more severe damage to the nerves coursing through the operative field. The saphenous nerve was less often affected. In 3 specimens (50%) treated with the dorsal approach, however, the saphenous nerve did not cross the operative field (Table 3). Likewise, the plantar approach posed less risk to the superficial fibular nerve (Figs. 6 and 7). The deep fibular nerve remained intact in both study groups. In addition, the medial plantar nerve remained intact in the plantar surgery cases. The distribution of tendon insertion of the tibialis anterior muscle into the medial cuneiform and the first metatarsal is presented in Table 4. Neither plantar nor dorsomedial plating resulted in any injury to the insertion of the tibialis anterior muscle (Figs. 8 and 9). In 2 cases of dorsal plating (33.3%), a small portion of the tibialis anterior tendon was engaged by the plate (Fig. 9).
In elective foot and ankle surgery, advances in implant techniques play an important role in promoting patient safety by reducing the incidence of complications and in increasing patient satisfaction by enabling early transition to full weightbearing and facilitating cosmetically superior results. Plantar plating for first TMT arthrodesis was developed with these goals in mind (10,11,13). The objective of the present study was to compare the advantages and disadvantages between the plantar operative technique and the standard procedure of fusion with dorsomedial plating. The present study also aimed to identify the anatomic structures at risk during each operative technique. To the best of our knowledge, the present study is the first anatomic on this topic. The findings supported our hypothesis that despite the differences in their injury profile, the 2 techniques are comparably safe, although the medial approach displayed certain advantages. The overall incidence of injury to arteries was low in both study groups. The medial approach disrupted the terminal vessels of the arterial system supplying the medial aspect of the first ray to a small extent. The relevant first digital branch of the medial plantar artery is a relatively small-caliber vessel. Given the extensive compensatory potential of the circulatory system (14) and that only the terminal branches of the vessels were affected, it is reasonable to assume that the relatively stronger first plantar metatarsal artery and first dorsal metatarsal artery will maintain an adequate blood supply of the first metatarsal and that of the proximal and distal phalanges (15). A greater issue is injury to the first plantar metatarsal artery (2 of 6 [33.3%] were injured) and the first dorsal metatarsal artery (1 of 6 [16.7%] injured) associated with the dorsomedial approach. In particular, when both arteries were injured at the same time, the relatively small-caliber first digital branch of the medial plantar artery must take over the supply. This carries a risk of impaired perfusion of the first TMT joint and the first ray. In addition, arterial injury can lead to postoperative bleeding, requiring subsequent revision, or result in hematoma formation and increased secondary infection rates, reducing patient satisfaction. From our findings, the medial plating was superior with regard to arterial considerations. Analysis of the venous injuries revealed substantially more pronounced anatomic variability than that of other structures. In 1 (1.17%) dorsal plating specimen, superficial venous drainage was achieved
Table 2 Veins injured during surgery Vein
Plantar Approach (n ¼ 6)
Dorsal Approach (n ¼ 6)
Great saphenous vein
6/6 (100%), tributaries severed 1/6 (16.7%), tributaries severed 2/5 (40%), main trunk severed
1/6 (16.7%), tributaries severed; 5/6 (83.3%), main trunk severed 2/5 (40%), tributaries severed; 2/5 (40%), main trunk severed 1/5 (20%), main trunk severed
Dorsal venous arch of foot Dorsalis pedis veins Fig. 5. Dorsomedial first tarsometatarsal joint arthrodesis using an H-plate.
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Table 3 Nerves injured during surgery Nerve
Plantar Approach (n ¼ 6)
Dorsal Approach (n ¼ 6)
Saphenous nerve Superficial fibular nerve
0 3/6 (50%), terminal branches severed1/6 (16.7%) main stem severed 0 0
1/3 (33%), main stem severed 3/6 (50%), terminal branches severed2/6 (33.3%), main stem severed 0 Not in operative field
Deep fibular nerve Medial plantar nerve
solely by the great saphenous vein. In another case of fusion with plantar plating, the dorsalis pedis veins were missing. In all specimens implanted with a plantar plate, the branches of the greater saphenous vein coursing from the medial aspect across the first TMT joint were severed (Fig. 6). To a lesser extent, this injury pattern also continued in the tributaries of the dorsal venous arch of the foot coming from the plantar aspect. Because the access is approximately at the level of the watershed between the plantar and dorsal venous outflow, drainage should be not be an issue. In contrast, the dorsomedial incision led to significantly more frequent injury to the main trunks, a plausible injury pattern given the typical vessel course across the operative field (16). Both methods were associated with a risk to the dorsalis pedis veins, running close to the lateral border of the TMT joint. Arthrodesis with plantar plating was associated with injury, mainly owing to implantation of compression screws. If compression screws were also implanted from the plantar aspect, the risk could be reduced further. A trend toward more favorable results with plantar plating was also recorded during evaluation of the surgery-related injury to the nerves. The dorsal approach was associated with a significantly greater risk of injury to the distal segments of the saphenous nerve. In contrast, plantar plating allowed this nerve to remain fully intact. In addition, previous studies reported an increased risk of injury to the branches of the superficial fibular nerve caused by a dorsal incision, favoring the plantar access route (17). Our findings have corroborated these results. The incidence of injury to the medial dorsal cutaneous nerve and intermediate dorsal cutaneous nerve was the same with both techniques. The cutaneous nerve and superficial fibular nerve cover a large area and hence cross both intervention territories. Such an extensive capillary distribution almost invariably lends itself to injury, in particular, during operative interventions involving the metatarsal-cuneiform and metatarsophalangeal joints and the tendon of the extensor hallucis longus muscle. Likewise, severing the superficial fibular nerve or the main trunk of the medial dorsal cutaneous
Fig. 7. Lesion profile pertaining to the great saphenous vein (circle) and the superficial fibular nerve (arrow) associated with dorsal access to the first tarsometatarsal joint.
nerve, which will be encountered more frequently with dorsal access routes, can be attributed to such branching. Injuries will manifest as postoperative scar pain in 5% of patients after hallux surgery (18) and in 45% in cases of direct injury to the medial dorsal cutaneous nerve (19). To avoid extensive nerve injury, intraoperative localization of a large-caliber anastomosis between the great saphenous vein and the dorsal venous arch of the foot approximately 2 cm proximally to the first MTP joint is recommended (16). The medial dorsal cutaneous nerve is located more deeply beneath the union of the “sentinel vein” and the dorsal venous arch (16), and caution must be used during the dorsal and plantar approach alike. For the deep fibular nerve and medial plantar nerve, no differences were recorded between the 2 methodsdthe nerve remained intact with both techniques. Because the medial plantar nerve does not appear in the dissection territory of the dorsal approach, a comparison with respect to the absence of its injury potential was inapplicable. Regarding the cosmetic results, the medial approach seems to be better, consistent with the theoretical considerations (15). The plantar approach fared better in terms of soft tissue coverage of the implants, because the plate was positioned beneath the abductor hallucis muscle (Fig. 10). This has potential positive implications regarding the infection rates. Supplementary interventions on the first ray, such as lateral release, can be easily accomplished using either approach (15,20–22). The potential advantages of the medial approach compared with the dorsomedial approach were summarized by Dayton et al (15) as follows. First, the medial approach provides good access to both sesamoid bones and, second, a superior range of motion of the metatarsophalangeal Table 4 Relative percentage of insertion of tibialis anterior muscle
Fig. 6. Lesion profile pertaining to the great saphenous vein (circle) and the superficial fibular nerve (arrow) associated with plantar access to the first tarsometatarsal joint.
Specimen No.
Insertion on Medial Cuneiform (%)
Insertion on First Metatarsal (%)
1, Right 1, Left 2, Right 2, Left 3, Right 3, Left 4, Right 4, Left 5, Right 5, Left 6, Right 6, Left Mean SD
64.3 70.0 52.9 68.4 34.5 86.2 52.4 52.2 57.1 60.0 73.7 65.2 61.4 12.6
35.7 30.0 47.1 31.6 65.5 13.8 47.6 47.8 42.9 40.0 26.3 34.8 38.6 12.6
Abbreviation: SD, standard deviation.
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Fig. 8. Insertions of the tibialis anterior muscle (circles) of 4 different specimens treated with plantar plating. (A and B) The tendon shown still attached to the insertion. (C and D) The tendon has been dissected away from the insertion. The specimen shown in (B) exhibited bipartite insertion on the medial cuneiform and base of the first metatarsal.
joint of the great toe because the dorsal structures will not be compromised. Third, in hallux valgus repair, the access is at the level of the deformity, supporting the repair. Finally, the medial approach results in a superior cosmetic appearance and good maintenance of the perfusion of the metatarsal head. The disadvantages cited by Dayton et al (15) included increased interference by hypertrophic scars, poor access to the first intermetatarsal space, and, occasionally, impeded lateral release. With respect to the latter 2 considerations, the medial approach allows for efficient lateral release (19) but also provides additional dorsal access to the first intermetatarsal space (18). Measurement of the insertion of the tibialis anterior muscle revealed that the medial cuneiform (mean 61.4%) had the largest relative share of the insertion. A mean share of 38.6% was attributed to the first metatarsal. Similar values were obtained in other studies. Thus, partially severing the tendon insertion during exposure of the first TMT joint will not increase the risk of structural instability. Caution should be used, however, because variants of normal also exist, with a predominant tendon share to the first metatarsal (23). These exceptions should be recognized intraoperatively to avoid
tendon rupture (11). Apart from 2 (2.34%) specimens treated with dorsal plating in which the muscle tendon was jammed beneath the proximal plate, no implant-related injury to the muscle insertion was recorded. Thus, dorsomedial plating requires the surgeon to exercise particular caution because the muscle tendon will be located at the site of plate implantation. In our study, the length of the incision was standardized and, similar to other anatomic studies on hallux valgus correction (24), extended the entire length of the first metatarsal with exposure of the first TMT joint. This corresponds to the standard approach used in the correction of extensive deformities (11,15). In addition, the access magnitude will thus be defined in relation to the size of the foot, allowing for comparisons between groups. We do not believe that the relatively low sample number (6 specimens per studied technique) significantly compromised the validity of our study. Although the operative interventions in our study were conducted on cadaveric specimens under optimal dissection conditions, the results adequately elucidated the potential benefits and drawbacks of the studied techniques. Hence, the present study has provided
Fig. 9. (A and B) Two examples of dorsomedial plating. The insertion of the tibialis anterior tendon (circles) remained intact. (B) The tendon was jammed under the proximal dorsal screw hole (arrow).
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Fig. 10. The arthrodesis plantar plate was largely covered by the abductor hallucis muscle (arrow). This muscle had been dissected in part and retracted with forceps.
surgeons with valuable anatomic information to guide the choice of technique, although the results should not be automatically extrapolated to daily clinical practice. Additional studies are needed before any conclusive recommendations can be given. In conclusion, both of the studied operative techniques were shown to be safe, well-established first TMT arthrodesis procedures. Arthrodesis with plantar plating offers specific advantages such as a more favorable access site morbidity profile and is thus an additional reliable tool in the foot and ankle surgeon’s repertoire. References 1. Rutherford RL. The Lapidus procedure for primus metatarsus adductus. J Am Podiatry Assoc 64:581–584, 1974.
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