Clinical Dossier

  • There is less pain with a PROstep™ MICA™ compared to a traditional open procedure.1
  • The PROstep™ MICA™ technique has shorter operative times and shows no increase in surgical complications—potentially less blood loss than open procedures.1 There is also minimal risk of neurovascular and tendon injury in chevron-akin MIS procedures like PROstep™.2
  • Minimally invasive surgery techniques are being adopted in all surgical specialties because of the advantages they bring to the surgeon and patient.3,4
  • PROstep™ MICA™ is an effective, minimally invasive surgical intervention that provides correction of forefoot and midfoot conditions comparable to first and second-generation surgical techniques.
    • Internal fixation PROstep™ MICA™ screws
    • Single-use, PROstep™ MICA™ burr
  • PROstep™ MICA™ internal fixation provides a stable fixation that avoids the rotational instability and complications usually associated with K-wire use.
  • Because it is minimally invasive, the PROstep™ MICA™ technique has improved cosmesis and is associated with a higher level of patient satisfaction.1

Wright Medical offers best in class surgeon training programs to educate physicians on PROstep™ MIS techniques. Surgeon training is essential to successful surgery outcomes.2

Hallux Valgus (HV), frequently referred to as bunions, is the most common forefoot deformity. It is characterized by abnormal angulation, rotation, and lateral deviation of the great toe at the first metatarsophalangeal joint.

Epidemiology studies indicate that across all age groups the prevalence of hallux valgus is greater in women (38%) compared with men (21%), with increasing prevalence as age increases. The higher prevalence among women may be due to footwear that is either poor or less forgiving, resulting in earlier and more frequent presentation.5,6

The often cited female prevalence can obscure the importance and the characteristic details of hallux valgus deformities in males,7 which are commonly hereditary in nature (mainly transmitted by the mother), with early onset and higher severity when compared to women.7

While studies show that sex and inheritance are important, other anatomical and biomechanical factors, such as anatomical metatarsal variants, including a long first metatarsal (probably most important in men), a rounded articulation, and metatarsus primus varus, play an important role. These variants increase the vulnerability to first-ray hypermobility, pes planus, and ligamentous laxity.8

HV also carries a noticeable impact on health related quality of life.9 Studies indicate that there are progressive reductions in both general health and foot -specific quality of life with increasing hallux valgus severity, leading to greater impairment on pain and functional assessment scales.9

Despite the high prevalence of foot problems and the significant impact foot impairment can have, foot problems often go unreported because many people, particularly older individuals, consider foot pain an inevitable consequence of ageing rather than a medical condition.10 Early, non-operative treatment can be useful in the management of hallux valgus symptoms. Options include nonsteroidal anti-inflammatory medications, steroid injections, activity modifications, shoe modifications, and orthotics or rocker bottom shoes. Prefabricated foot orthoses and rocker-sole footwear were similarly effective at reducing foot pain in people with first metatarsophalangeal joint osteoarthritis in a clinical study, although the prefabricated foot orthoses had greater adherence and fewer associated adverse events.9

If pain persists, however, a minimally invasive surgical intervention, like PROstep™ MICA™, is an option. Surgical interventions aimed at correcting or slowing the progression of HV deformity have a number of beneficial effects on localized pain relief. Surgical correction of hallux valgus allows improved ambulation and quality of life scores.5,9

Surgical correction of hallux valgus rebalances the first ray, correcting features that characterize the joint deformity.11 There have been more than 150 different techniques described for surgical correction of hallux valgus.11,12

Regardless of technique, the technical goals of surgery are to correct the HVA/IMA, create a congruent MTP joint with sesamoid realignment, remove the medial eminence, retain functional range of motion of the MTP joint, and maintain normal WB mechanics. The clinical goals are to produce a functional, painless first ray and the ability to wear shoes of the patient’s choice, such as high heels for women.13 The latter is of particular importance to patients, as an inability to wear the shoe of choice is strongly associated with dissatisfaction with the outcome of hallux valgus treatment.5

First generation procedures, such as the open scarf corrections, are generally effective when appropriately executed.14 Open procedures include soft tissue release and medial exostostomy combined with either proximal or distal osteotomy of the first metatarsal.

Unfortunately, the outcome of an open surgical correction can be unsatisfactory to the surgeon and undesirable for the patient. Cadaveric study indicates that the standard orthopaedic approaches to foot and ankle surgery all carry a risk of cutaneous nerve injury and that wide patient variability in the anatomic location of nerve branches complicates this risk potential.15 Clinical evidence also indicates that open procedures can be associated with significant postoperative pain, stiffness and disability.1,14

A second generation technique, a distal transverse osteotomy of the first metatarsal stabilized with a K-wire, is an inexpensive hallux valgus correction, but does not provide rigid stable fixation, introducing the potential for dorsal and plantar displacement of the metatarsal head.1 The use of a K-wire is also associated with complications of superficial infection, stress fracture, and delayed union.1 There have also been clinical reports of metatarsal and proximal phalanx lateral cortical fractures, overcorrection of the joint deformity, stiffness of the metatarsophalangeal joint, and in a small number of cases, chronic regional pain syndrome.1

Today, a third generation, minimally invasive surgery (MIS) is available. MIS combines a modified chevron-Akin technique with internal fixation to add extra stability to the surgical correction.1,16 PROstep™ MICA™ is a chevron-shaped osteotomy of the first metatarsal and an Akin-type osteotomy of the proximal phalanx of the hallux, both performed percutaneously using a specially designed burr under image x-ray guidance using a mini C arm that allows assessment of bony alignment. The surgical site is then internally rigidly fixed with the PROstep™ MICA™ screw, also aided by the mini C arm. The screw has been specifically designed with a flanged head to maintain circumferential cortical fixation when inserted flush to the bone.16

PROstep™ MICA™ is indicated for symptomatic mild to moderate hallux valgus deformity but with experience severe deformity corrections can be corrected using 100% displacement of the osteotomy.16

Unlike open procedures with large incision sites, the PROstep™ MICA™ technique has only minimal risk of neurovascular and tendon injury.2 The main neurovascular structures at risk are the superficial peroneal nerve and the arterial blood supply to the first metatarsal head. An anatomical study of minimally invasive surgical correction of HV found no greater incidence of nerve injury or blood vessel damage and no tendon injury.2

A prospective, randomized trial comparing the Redfern/Vernois PROstep™ MICA™ technique described by Redfern and Vernois with a scarf-Akin osteotomy for the correction of hallux valgus was published.1

Fifty-one subjects were randomized into two surgical groups. Outcome measures at three timepoints (preoperative and 6- and 26-weeks postoperative) included AOFAS Hallux Metatarsophalangeal-Interphalangeal Score, a visual analog pain score, hallux valgus angle (HVA), and intermetatarsal angle (IMA). HVA and IMA correction and report of complications were comparable in both techniques. The PROstep™ MICA™ technique, however, had shorter operative times, improved cosmesis, and a higher level of patient satisfaction.1

Another recently reported randomized trial comparing the Redfern/Vernois PROstep™ MICA™ technique to an open scarf-Akin osteotomy in 50 patients found similar surgical correction between the two procedures, but significantly lower pain levels in the early postoperative phase (post-operative day 1 and post-operative week 6), significantly shorter scar length, and a greater proportion reporting high satisfaction for patients with correction using the PROstep™ MICA™ technique.14

Hallux rigidus (HR) is the second most common pathology affecting the great toe, after hallux valgus deformities.17 Like hallux valgus, HR is associated with degenerative changes of the first metatarsophalangeal joint.17 Symptoms are related to degeneration of the first MTP joint and results from cartilage wear, altered joint mechanics, and progression of osteophyte formation. Patients experience pain that seems to worsen on push off gait, dorsiflexion of the great toe, and stiffness.17 A patient history will reveal pain with weight-bearing activities that is lessened by rest or a weightless state.18 This pain usually arises from shoe-related pressure on prominent osteophytes or impingement of dorsal osteophytes.

Epidemiology studies indicate that the prevalence of hallux rigidus is greater in women by a 2 to 1 margin.17

Coughlin and Shurnas reported findings in 110 patients who had undergone surgery for hallux rigidus.19 The authors noted that on final evaluation, about 80% of the patients showed bilateral involvement. In the bilateral cases, 98% of the patients had a positive family history. Although 62% of the patients in the Coughlin and Shurnas report were women, other investigators have reported a slight male predominance.

Early, non-operative treatment can be useful in managing symptoms of HR. Options include nonsteroidal anti-inflammatory medications, steroid injections, shoe modifications, orthotics, and activity modifications.17 If pain persists, however, minimally invasive surgery is an option.17,20

PROstep™ Surgical Intervention
While there are several surgical options, cheilectomy is attractive because there is minimal bone loss, joint range of motion is preserved, and the potential for other procedures to be employed if needed.21 The PROstep™ procedure has been effectively used for this surgical correction. The PROstep™ technique requires a small (4-8mm) incision dorsal to the first metatarsal neck.12,22 This small incision has improved cosmesis relative to the open procedure which requires longitudinal incision that extends 3cm distal and proximal to the first metatarsophalangeal joint.22

Redfern and colleagues have reported on their experience in using a minimally invasive cheilectomy for correction of HR.12 Clinical results from 44 consecutive feet provided a mean subjective percentage improvement in symptoms of 90%, with 86% of cases returning to ordinary footwear and normal daily activity/employment 1 week following surgery.12 Other clinical studies have reported similar success with the minimally invasive cheilectomy technique.12,23,24

Osteotomies performed in the calcalneal space are undertaken to correct the deformities of a malaligned calcaneus and alleviate the functional limitations that are associated with them.25 The ultimate goal of all osteotomies is to relieve pain, improve alignment and walking, and reduce the likelihood of arthritis.

The structure of the calcaneus requires a unique surgical approach in surgical corrections of the calcaneus. Various surgical options have been available—closed reduction and percutaneous fixation, open reduction and internal fixation, limited open reduction, and subtalar arthrodesis.

Calcaneal osteotomy is an operative technique used to correct hindfoot deformities and injury. Traditional open operative approaches involve a lateral incision that begins at the proximal tip of the fibula, turns 90° at the heel and continues laterally to the calcaneus. This extensile, L-shaped, approach has been favored because it provides excellent exposure and access to manipulation and fixation of the calcaneus.26

Unfortunately, this traditional approach, while widely used, is also associated with a complication rate estimated at 10-28%27,28 including flap necrosis and wound infection.26 Minor and major wound complications are of concern because of the thin and vulnerable skin over the lateral calcaneal wall.26

A minimally invasive surgical procedure minimizes the wound complication rate,26,27,29 have shorter operating times, can reduce the length of hospital stays, and improves cosmesis by reducing the incision length to two, minor puncture entries. Minimally invasive calcaneal osteotomies also reduce the risk to anatomical structures posed by the open approach28 and avoid affecting incisions that may be required for other elements of hindfoot reconstruction.30

A retrospective, case controlled cohort comparison of the open osteotomy technique and a minimally invasive calcaneal osteotomy in 81 patients reported significantly fewer wound complications and no reports of post-operative neuropathy in the MIS group.27 An anatomic study comparing these same two approaches demonstrated potentially fewer anatomic injuries with a minimally invasive approach than traditional open surgery.28

References

  1. Lam P, Lee M, Xing J, DiNallo M. Percutaneous Surgery for Mild to Moderate Hallux Valgus.
    Foot Ankle Clin N Am 2016; 21: 459-477. https://www.ncbi.nlm.nih.gov/pubmed/27524701
  2. Dhukaram V, Chapman AP, Upadhyay PK. Minimally Invasive Forefoot Surgery: A Cadaveric Study.
    Foot Ankle Intl 2012: 33(12): 1139-1144. https://www.ncbi.nlm.nih.gov/pubmed/23199867
  3. Trnka HJ, Krenn S, Schuh R. Minimally Invasive Hallux Valgus Surgery: a Critical Review of the Evidence. International Orthopaedics 2013; 37: 1731-1735. https://www.ncbi.nlm.nih.gov/pubmed/23989262
  4. Brogan K, Lindisfarne E, Akehurts H, Farook U, Shrier W, Palmer S. Minimally Invasive and Open Distal Chevron Osteotomy for Mild to Moderate Hallux Valgus. Foot Ankle Intl 2016; 37 (11): 1197-1204. https://www.ncbi.nlm.nih.gov/pubmed/27381179
  5. Saro C, Jensen I, Lindgren U, Fellander-Tsai L. Quality of Life Outcome After Hallux Valgus Surgery.
    Qual Life Res 2007; 16: 731-738. https://www.ncbi.nlm.nih.gov/pubmed/17342454
  6. Roddy E, Zhang W, Doherty M. Prevalence and Associations of Hallux Valgus in a Primary Care Population. Arthritis Rheum 2008; 59: 857-862. https://www.ncbi.nlm.nih.gov/pubmed/18512715
  7. Nery C, Coughlin MJ, Baumfeld D, Ballerini FJ, Kobata S. Hallux Valgus in Males—Part 1: Demographics, Etiology and Comparative Radiology. Foot Ankle Intl 34 (5): 629-85. https://www.ncbi.nlm.nih.gov/pubmed/23386751
  8. Perera AM, Mason L, Stephens MM. The Pathogenesis of Hallux Valgus. J Bone Joint Surg Am. 2011 Sep 7;93(17):1650-61. https://www.ncbi.nlm.nih.gov/pubmed/21915581
  9. Menz HB, Roddy E, Thomas E, Croft PR. Impact of Hallux Valgus Severity on General Foot-Specific Health-Related Quality of Life. Arthritis Care & Research 2011; 63 (3): 396-404. https://www.ncbi.nlm.nih.gov/pubmed/21080349
  10. Menz HB, Lord SR. The Contribution of Foot Problems to Mobility Impairment and Falls in Community-Dwelling Older People. J Am Geriatr Soc 2011; 49: 1651-6. https://www.ncbi.nlm.nih.gov/pubmed/11843999
  11. Maffulli N, Longo UG, Marinozzi A, Denaro V. Hallux Valgus: Effectiveness and Safety of Minimally Invasive Surgery: A Systematic Review. British Medical Bulletin 2011; 97: 149-167. https://www.ncbi.nlm.nih.gov/pubmed/20710024
  12. Redfern D, Vernois J, Legre BP. Percutaneous Surgery of the Forefoot. Clin Podiatr Med Surg 2015; 32: 291-332. https://www.ncbi.nlm.nih.gov/pubmed/26117570
  13. Coughlin M, Saltzman C, Anderson RB [eds] (2013). Mann’s Surgery of the Foot and Ankle, 9th Ed. Amsterdam, Netherlands: Elsevier. https://www.elsevier.com/books/mann-s-surgery-of-the-foot-and-ankle-2-volume-set/coughlin/978-0-323-07242-7
  14. Lee M, Walsh J, Smith MM, Ling J, Wines A, Lam P. Hallux Valgus Correction Comparing Percutaneous Chevron/Akin (PECA) and Open Scarf/Akin Osteotomies. Foot Ankle Intl 2017; 38(8): 838-846. https://www.ncbi.nlm.nih.gov/pubmed/28476096
  15. Pont MP, Assal M, Stern R, Fasel JH. Cutaneous Sensory Nerve Injury During Surgical Approaches to the Foot and Ankle; A Cadaveric Anatomic Study. Foot and Ankle Surgery 2007; 13: 182-188. https://www.footanklesurgery-journal.com/article/S1268-7731(07)00051-3/abstract?code=fas-site
  16. Redfern DJ, Vernois J. Minimally Invasive Chevron Akin (MICA) for Correction of Hallux Valgus. Techniques in Foot & Ankle Surgery 2016; 15 (1): 3-11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4564048/
  17. Razik A, Sott AH. Cheilectomy for Hallux Rigidus. Foot Ankle Clin N Am 2016; 21: 451-457. https://www.ncbi.nlm.nih.gov/pubmed/27524700
  18. Herr MJ, Kile TA. First Metatarsophalangeal Joint Arthrodesis with Conical Reaming and Crossed Dual Compression Screw Fixation. Techniques in Foot and Ankle Surgery 2005; 4(2): 85-94. https://journals.lww.com/techfootankle/Abstract/2005/06000/First_Metatarsophalangeal_Joint_Arthrodesis_With.4.aspx
  19. Coughlin MJ, Shurnas PS. Hallux Rigidus: Grading and Long-term Results of Operative Treatment.
    J Bone Joint Surgery 2003; 85-A (11): 2072-2088. https://www.ncbi.nlm.nih.gov/pubmed/14630834
  20. Schmid T, Younger A. First Metatarsophalangeal Joint Degeneration: Arthroscopic Treatment.
    Foot Ankle Clin N Am 2015; 20: 413-420. https://www.ncbi.nlm.nih.gov/pubmed/26320556
  21. Harrison T, Fawzy E, Dinah F, Palmer S. Prospective Assessment of Dorsal Cheilectomy for Hallux Rigidus Using a Patient-reported Outcome Score. J Foot Ankle Surgery 2010; 49: 232-237. https://www.ncbi.nlm.nih.gov/pubmed/20303801
  22. Walter R, Perera A. Open, Arthroscopic and Percutaneous Cheilectomy for Hallux Rigidus.
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  23. Dawe ECJ, Ball T, Annamalai S, et al. Early Results of Minimally Invasive Cheilectomy for Painful Hallux Rigidus. J Bone Joint Surg Br 2012; 94B (Supp) XXII: 33. https://online.boneandjoint.org.uk/doi/abs/10.1302/1358-992X.94BSUPP_XXII.BOFAS2010-033
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  25. Tennant JN, Carmont M, Phisitkul P. Calcaneus Osteotomy. Curr Rev Musculoskelet Med 2014 ; 7: 271-276. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4596212/
  26. Khurana A, Dhillon MS, Prabhakar S, John R. Outcome Evaluation of Minimally Invasive Surgery Versus Extensile Lateral Approach in Management of Displaced Intra-articular Calcaneal Fractures: A Randomised Control Trial. Foot (Edinb). 2017 Jun;31:23-30. https://www.ncbi.nlm.nih.gov/pubmed/28324822
  27. Kendal AR, Khalid A, Ball T, Rogers M, Cooke P, Sharp R. Complications of Minimally Invasive Calcaneal Osteotomy Versus Open Osteotomy. Foot Ankle Intl 2015; 36 (6): 685-690. https://www.ncbi.nlm.nih.gov/pubmed/25677362
  28. Veljkovic A, Tennant J, Rungprai C, Abbas KZ, Phisitkul P. An Anatomic Study of the Percutaneous Endoscopically Assisted Calcaneal Osteotomy Technique to Correct Hindfoot Malalignment.
    Foot Ankle Intl 2017; 38 (2): 192-199. https://www.ncbi.nlm.nih.gov/pubmed/27765868
  29. Vernois J, Redfern D, Ferraz L, Laborde J. Minimally Invasive Surgery Osteotomy of the Hindfoot.
    Clin Podiatr Med Surg 2015; 32: 419-434. https://www.ncbi.nlm.nih.gov/pubmed/26117576
  30. Guyton GP. Minimally Invasive Osteotomies of the Calcaneus. Foot Ankle Clin N Am 2016; 21: 551-566. https://www.ncbi.nlm.nih.gov/pubmed/27524705
  31. Shirzad K, Kiesau CD, DeOrio JK, Parekh SG. Lesser Toe Deformities. J Am Acad Orthop Surg 2011; 19 (8): 505-514. https://www.ncbi.nlm.nih.gov/pubmed/21807918
  32. Richman SH, Siqueira MB, McCullough KA, Berkowitz MJ. Correction of Hammertoe Deformity with Novel Intramedullary PIP Fusion Device Versus K-wire Fixation. Foot Ankle Intl 2017; 38 (2): 174-180. https://www.ncbi.nlm.nih.gov/pubmed/27756869
  33. Smith BW, Coughlin MJ. Disorders of the Lesser Toes. Sports Med Arthrosc Rev 2009; 17: 167-174. https://www.ncbi.nlm.nih.gov/pubmed/19680113
  34. Boffeli TJ, Thompson JC, Tabatt JA. Two-pin Fixation of Proximal Interphalangeal Joint Fusion for Hammertoe Correction. J Foot Ankle Surgery 2016; 55: 480-487. https://www.ncbi.nlm.nih.gov/pubmed/26878808