Techniques in Foot & Ankle Surgery 7(1):31–40, 2008 Ó 2008 Lippincott Williams & Wilkins, Philadelphia S P E C I A L F O C U S j j Resurfacing of the First Metatarsal Head in the Treatment of Hallux Rigidus Carl T. Hasselman, MD University of Pittsburgh Medical Center Pittsburgh, PA Naomi Shields, MD University of Kansas Wichita, KS | ABSTRACT Surgical techniques for the treatment of hallux rigidus have evolved during the past decade. Previously, main treatments were cheilectomy for earlier stages of hallux rigidus and resection arthroplasty or arthrodesis for advanced stages. Although arthrodesis has been considered the ‘‘gold standard’’ for advanced hallux rigidus, in younger and more active patients, activity, functional, and shoe wear limitations are undesirable outcomes of this procedure. Alternative surgical procedures have been developed for advanced hallux rigidus, with varying outcomes and complications. Endoprosthetic replacement, which has been well described in the past and revisited recently, has higher complication rates than more traditional approaches. Hemiarthroplasty using various prosthetic resurfacings of the phalangeal base has been reported with variable success rates as well. Soft tissue interpositional arthroplasty has been shown to have inconsistent results and significant stiffness. The Arthrosurface HemiCAP prosthesis has been described for the treatment of full-thickness chondral and osteochondral defects of the shoulder, hip, and knee with high success rates to date. More recently, the technology was expanded to allow for metallic resurfacing of the first metatarsal head as an alternative technique with the potential to maintain motion and function. By using this implant alone or combined with soft tissue interpositional arthroplasty, or proximal phalanx osteotomies, even severe forms of hallux rigidus can be treated. During the past 30 months, the authors have treated more than 100 patients with hemiarthroplasty of the first metatarsophalangeal joint using the HemiCAP prosthesis (Arthrosurface Inc, Franklin, Mass). To date, there have been 2 failures, one from infection and the other from a Address correspondence and reprint requests to Carl T. Hasselman, MD, University of Pittsburgh Medical Center, Pittsburgh, PA 15215. E-mail: [email protected]. related procedure. Twenty-five of the first 30 patients with stage II or III hallux rigidus consented to participate in a follow-up study. The mean age of these patients was 51 years. Mean follow-up was 20 months. The mean postoperative increase in range of motion of the joint was 42 degrees (baseline, 23 degrees; postoperative, 65 degrees). The mean American Orthopaedic Foot and Ankle Society and 36-item Short-Form Health Survey Questionnaire scores were 82.1 and 96.1, respectively. All patients were very satisfied with their results and said that they would have the procedure performed again. Although long-term follow-up is still needed, the short-term results are very promising. In addition, future treatment options are maintained because of minimal bone resection at the time of HemiCAP implantation, and conversion to arthrodesis or resection arthroplasty can be performed should the need arise. Keywords: hallux rigidus, first MTP joint, endoprosthesis, HemiCAP, Arthrosurface, hallux limitus, resurfacing, hemiarthroplasty, arthritic bunion H allux rigidus is a progressive arthritic process of the first metatarsophalangeal (MTP) joint that causes pain, stiffness, and enlargement of the joint.1,2 A multitude of surgical procedures has been described to address the pain and stiffness associated with this disease, including cheilectomy, 3,4 osteotomies, 5,6 resection arthroplasty,7,8 interpositional arthroplasty,9Y11 hemiarthroplasty, 1 2 , 1 3 total joint arthroplasty, 1 4 , 1 5 and arthrodesis.16Y18 Although cheilectomy and osteotomies may be suitable for stages I and II hallux rigidus, these procedures are not effective for the treatment of more advanced stages.19 Because resection arthroplasty has been associated with transfer metatarsalgia, postoperative deformities, and loss of push-off strength, its use has been recommended only for elderly and sedentary patients.20 Interpositional arthroplasties have recently been gaining popularity. However, long-term follow-up studies are Volume 7, Issue 1 Copyright @ 2008 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. 31 Special Focus: Hasselman and Shields lacking for the newer techniques. Hemiarthroplasties that resurface the proximal phalangeal base have shown promise as well, but stiffness, continued pain, and prosthetic loosening are still limiting factors associated with these procedures. Total joint arthroplasties have been fraught with complications in the younger and more active patients with loosening and malalignment common in endoprosthetic replacement.14,21 Arthrodesis has been considered the ‘‘gold standard’’ for treating advanced hallux rigidus. However, limitations in shoe wear, permanent activity modifications, complications of malunion or nonunion, and transfer metatarsalgia have made this procedure less attractive to the younger active patient.22Y25 A treatment alternative that can reliably relieve pain, maintain motion without affecting strength or stability, while maintaining future treatment options is greatly needed for this patient population. In advanced stages of hallux rigidus, the metatarsal head is severely denuded of its articular cartilage; however, the sesamoid articulations are usually spared except in the most extreme cases. Quite often, the metatarsal head is the more damaged side of the joint. The use of acellular human tissue has recently been described to resurface the metatarsal head with good immediate results10; however, the short- and long-term wear on such a graft is still in question. A metallic implant to resurface the metatarsal head with minimal bone resection and without altering the sesamoid articulation was needed. The implant should also not interfere with the normal balance of the flexor-extensors, plantar plate, or adductor-abductor mechanisms. The HemiCAP System (Arthrosurface Inc, Franklin, Mass) was introduced several years ago to resurface damaged articular surfaces and restore the patient’s own unique joint geometry with minimal bone resection. The implant is composed of a cobalt-chromium alloy for the articular portion, which attaches to a titanium alloy taper post (fixation component) via a Morse taper (Fig. 1). Earliest uses were in the shoulder, hip, and knee, with encouraging clinical outcomes.26Y29 Thirty months ago, the device was approved and introduced for resurfacing of the metatarsal head in hallux rigidus. We present our early experience with this new technique on inlay resurfacing of the metatarsal head. | INDICATIONS AND assessed to determine his or her desired outcome from the procedure. The ideal patient for this procedure demonstrates signs and symptoms of advanced hallux rigidus and expects to remain active and maintain motion. This patient opposes permanent limitations in shoe wear and physical activities and fears the limited weight bearing associated with the immediate postoperative care. Absolute contraindications for this procedure include significant bone demineralization or inadequate bone stock, neuropathic changes of the foot, metal sensitivity, and a history of osteomyelitis or persistent infection. Relative contraindications include infections at remote sites that may spread to the implant, osteoporosis, chronic instability of the MTP joint, and vascular disease that would impair wound healing. Gout and inflammatory arthritis may be relative contraindications; however, the authors have used the HemiCAP in a small number of these patients. These patients typically have less postoperative range of motion than most, but their motion has been adequate for activities of daily living. Although a previous failed osteotomy and/or cheilectomy is not a contraindication, the soft tissues should be adequate to allow for wound coverage and healing before performing this procedure. The patient should also be counseled that this technique is relatively new, and although early results are promising,30 longterm outcomes are still lacking. | PREOPERATIVE PLANNING CONTRAINDICATIONS HemiCAP implantation is indicated in patients with stages II to IV hallux rigidus who have failed conservative treatment, including activity limitations, shoe wear modifications, and nonsteroidal anti-inflammatory medications. 1 Each patient should be individually 32 FIGURE 1. The HemiCAP implant: titanium alloy fixation component connected via Morse taper to the cobalt chromium alloy articular contoured component. A full preoperative assessment of the patient includes general health, comorbid conditions, and physical examination of the entire lower extremity to ensure optimal outcome. However, there are no age limitations for this implant, and preoperative range of motion has not been found to have any effect on postoperative results. Dorsal Techniques in Foot & Ankle Surgery Copyright @ 2008 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Special Focus: First Metatarsal Head Resurfacing in Hallux Rigidus | TECHNIQUE FIGURE 2. Anteroposterior and lateral radiographs of young female and avid runner who developed avascular necrosis and subsequent arthrosis of the metatarsal head after a distal chevron osteotomy for hallux valgus. pain of the first MTP joint with increased activities, barefoot walking, or soft sole shoe wear are the classic complaints. The sesamoid articulation should be assessed by direct palpation while manually dorsiflexing the toe to ensure that this articular surface is not a major source of the patient’s symptoms. If the sesamoids seem to be involved in the arthritic process, then other procedures along with the HemiCAP or arthrodesis should be planned; however, sesamoid involvement with the arthritic process is not a contraindication to this technique. Preoperative weight bearing anteroposterior, oblique, and lateral radiographs should be taken to evaluate the joint and rule out other causes of pain (Fig. 2). Evaluation of joint alignment is important. If there is an increased intrametatarsal angle or halgus valgus deformity, alignment correction of the joint must be done either in conjunction with or before the cheilectomy or HemiCAP arthroplasty. Intraoperative assessment of the metatarsal articular surface will further guide the surgical management plan: if less than 50% of the metatarsal head is involved and good articular surface remains plantarly, a cheilectomy should be performed; whereas HemiCAP implantation is indicated in patients with advanced loss of articular cartilage. Although the HemiCAP implant is available in 12- and 15-mm-diameter sizes to accommodate most metatarsal head dimensions, it has been our experience that the 15-mm size has been used predominantly. The 12-mm implant works best in cases of an isolated central osteochondral defect of the metatarsal head. In addition, a smaller fixation component in combination with the 12-mm implant has been successfully used in the treatment of Freiberg’s disease of the second metatarsal head. The patient is placed supine on the operating table, with the operative extremity in a well-padded position. The procedure can be done with either a regional popliteal block and a calf tourniquet or an ankle block with an Esmarch bandage wrapped around the ankle. A dorsal incision is made centered over the MTP joint and slightly medial to the extensor hallucis tendon. The subcutaneous tissues are spread gently to expose the dorsal joint capsule, with care being taken to protect the dorsomedial cutaneous nerve. The extensor hallucis longus tendon is freed from the capsule and retracted laterally to keep the tendon within its sheath (Fig. 3). A longitudinal arthrotomy is made along the medial border of the joint, and the capsule is elevated off the bone. A complete release of the collateral ligaments, sesamoidal suspension ligaments, and capsule should be made so that the entire joint, including the sesamoids, is easily visualized (Fig. 4). It is very important to visualize the articular edge of the sesamoid Christi on the metatarsal head because this is the landmark for placement and sizing of the implant. In advanced hallux rigidus, the sesamoids and flexor hallucis brevis will have fibrotic adhesions to the metatarsal head that will limit dorsiflexion postoperatively. A curved osteotome, freer or McGlammary elevator can be used to release these plantar adhesions. Care should be taken to avoid damage to the metatarsal-sesamoid articulation. A cheilectomy is not performed at this time to avoid overresection of bone. Once the joint is exposed, HemiCAP implantation is performed after the stepwise arrangement of the instrument set from left to right in the system tray. A cannulated drill guide is used to establish perpendicular access to the joint surface and to place a guide wire into the center of the metatarsal head (Fig. 5). FIGURE 3. Intraoperative photograph showing incision placement, capsular exposure, and retraction of the extensor hallucis longus. Volume 7, Issue 1 Copyright @ 2008 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. 33 Special Focus: Hasselman and Shields FIGURE 4. Complete release of the soft tissues to expose the entire joint. The collateral and plantar ligaments should be completely released. FIGURE 6. The guide wire is viewed dorsally to ensure that the wire is centered in the metatarsal shaft in the medial/lateral plane. Once the guidewire is inserted, obtain fluoroscopic anteroposterior and lateral views to ensure that it is centered within the shaft in both the dorsal-plantar and mediallateral directions (Fig. 6). A cannulated double-step drill is inserted over the guide wire, and the metatarsal head is drilled until the proximal shoulder of the drill is flush with the plantar articular surface of the metatarsal head (Fig. 7). In most cases, the only normal articular surface remaining is the plantar cartilage, and this surface is used as the reference for depth determination. The drill is removed, and a cannulated tap is inserted over the guide wire. The hole is tapped until the etched depth mark on the tap is flush with the plantar articular surface of the metatarsal head. The tap is removed, and the taper post is inserted over the guide wire. The taper post is inserted until the etched line on the driver is flush with the articular surface of the metatarsal head (Fig. 8). The apex height of the final implant relative to the native articular surface can be checked at this time by using a trial cap provided with the taper post. With the taper post in place at the desired depth, 3-dimensional mapping of the metatarsal head determines the curvatures of the native surface geometry. A centering shaft is fully seated in the cleaned taper of the fixation component. The contact probe is placed over the centering shaft, and the probe tip is used to map the normal articular surface of the metatarsal head (Fig. 9). Although the technique manual refers to 4 contact areas (dorsal, plantar, medial, and lateral) in most cases of hallux rigidus, only 2 surfaces still have healthy articular cartilage, the plantar surface and either the medial or lateral side of the joint. Measurements of the joint offsets in the inferior and medial/lateral surfaces are now made. Using a sizing card provided with the implants, the appropriate shaped implant and FIGURE 5. Intraoperative photograph showing the drill guide firmly seated against the metatarsal head in the position desired for implant placement. 34 FIGURE 7. The drill is driven until seen flush against the articular surface as shown. Techniques in Foot & Ankle Surgery Copyright @ 2008 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Special Focus: First Metatarsal Head Resurfacing in Hallux Rigidus FIGURE 8. The taper post is placed. Note that the post is advanced until the line on the driver is flush with the articular surface. FIGURE 10. The sizing card with offset measurements showing that a size 1.5-mm 3.5-mm implant should be used. The reamer size is based on the largest offset of the implant chosen. corresponding reamer are now chosen (Fig. 10). The centering shaft and contact probe are removed, the guide pin is reinserted into the taper post, the corresponding reamer (based on the offset measurements) is placed over the guide pin, and the implant bed is prepared in the metatarsal head (Fig. 11). The reamer is attached to a high speed drill and should be running at full speed before contact with the metatarsal head to avoid shearing or shattering of the bone or remaining articular surface. The reamer can be very aggressive, so gentle pressure should be exerted while slowly advancing the reamer over the guide pin. Care should be taken to maintain a proper axis and not bend the guide pin while reaming. The reaming will stop upon contact with the top of the taper post. The guide pin and reamer are now removed, and the taper is cleaned. All reamings are removed from the wound, and frayed edges of the articular surface are cleaned (Fig. 12). A sizing trial that matches the offset profile of the chosen implant is now seated into the taper post to ensure proper orientation and fit of the implant. The fit of the sizing trial is confirmed by ensuring that it is congruent with the edges of the surrounding articular surface. Again, in most cases, this will be the plantar and medial/lateral surfaces. Although it is not necessary in most cases, decompression of the joint is possible by altering the joint line and driving the taper post deeper into the metatarsal head. The taper post driver is placed back onto the taper post and turned clockwise. For every quarter turn of the driver, the taper post advances 1 mm deeper. It is not recommended to decompress the joint more than 2 or 3 mm to avoid altering the sesamoid articulation. Once the taper post has been advanced, it is necessary to repeat the reaming step to ensure that the articular component is properly seated in the taper post and implant bed. FIGURE 9. The centering post is inserted into the taper post with the contact probe measuring the offset of the plantar surface. FIGURE 11. Reaming of the metatarsal head over the guide wire. Volume 7, Issue 1 Copyright @ 2008 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. 35 Special Focus: Hasselman and Shields FIGURE 12. The reamed metatarsal head and taper post are cleared of all debris before seating the implant. FIGURE 14. The implant is seated in the taper post before cheilectomy. Once the sizing trial confirms proper fit of the implant, the trial is removed, and the area is cleaned once again, with focus on the taper to ensure proper seating of the final implant. At this time, a full cheilectomy of the metatarsal head is performed over the sizing trial, thereby avoiding any damage to the actual implant. The articular component is placed in the appropriate medial/lateral and dorsal/plantar orientation using the suction-holding device provided with the instrument set (Fig. 13). An impactor is used on the implant with gentle taps to ensure that the implant is fully seated on the taper post and bone bed (Fig. 14). The cheilectomy is checked with the implant in place to ensure an adequate resection of bone (Fig. 15). Bone wax can be placed on the resected surface of the metatarsal to minimize postoperative hematoma formation (Fig. 16). At this time, attention is turned to the phalangeal side of the joint. Many different approaches can be taken to address phalangeal pathology. Some surgeons perform a cheilectomy of the proximal phalanx. This is usually successful if less than 50% of the articular cartilage is damaged. Other surgeons have combined a Moberg proximal phalangeal osteotomy 5 with the HemiCAP technique to improve postoperative range of motion. If more than 50% of the proximal phalanx surface is involved, we combine the HemiCAP implant with a soft tissue resurfacing of the proximal phalanx. A saw is used to remove the dorsal osteophyte, similar to what has been described by others (Fig. 17).9Y11 Do not resect the plantar cortex to avoid disrupting the flexor attachment. A portion of dorsal capsule large enough to cover the proximal phalanx base is completely excised (Fig. 18) and sutured to the base of the proximal phalanx (Fig. 19). Suture anchors placed centrally or drill holes in the corners are used to secure the capsule in place with sutures. Previously, metallic suture anchors were FIGURE 13. The implant is being held by the suction holding device. The orientation of the implant is imprinted on the inside to allow verification of proper alignment. FIGURE 15. A lateral view of the metatarsal showing the appearance after a full cheilectomy is performed to remove any osteophytes or nonarticular cartilage that contacts the implant. 36 Techniques in Foot & Ankle Surgery Copyright @ 2008 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Special Focus: First Metatarsal Head Resurfacing in Hallux Rigidus FIGURE 16. Dorsal view of the metatarsal after cheilectomy and application of bone wax to the cut surfaces. used, but because of a rare experience with metallosis caused by the anchors contacting the implant, bioabsorbable anchors are now recommended. If the capsule is inadequate to cover the phalangeal base because of previous surgical interventions, an acellular dermal allograft (Graft Jacket, Wright Medical) or xenograft (Zimmer Patch, Zimmer Inc or Surgimend, TEI Biosciences) can be used as a soft tissue interposition. In several cases of severe sesamoid involvement, the technique of Berlet et al10 was added to the HemiCAP procedure to provide soft tissue interposition for the sesamoids. However, it remains unclear if this provides any long-term benefits.9 Once the phalangeal side has been addressed, the joint is taken through a range of motion. Intraoperatively, 90 degrees of dorsiflexion between the metatarsal and phalanx should be achieved. The wound is now copiously irrigated and closed in layers. In most cases where the FIGURE 17. Resection of the dorsal osteophytes of the phalangeal base. Note that articular cartilage persists on the plantar 25% of the base. FIGURE 18. The dorsal capsule is cut to the size of the phalangeal base. Hemostats are placed in each corner to prevent the graft from rolling up once it has been prepared. Suture anchors have been placed into the proximal phalanx base to secure the graft. capsule has been removed for phalangeal resurfacing, there is still adequate capsule for closure because of the redundancy of the capsule after the cheilectomy has been done. A compressive, but not bulky (to allow free dorsiflexion), dressing is applied, and the patient is encouraged to fully weight bear postoperatively. | POSTOPERATIVE COURSE A stiff-soled shoe is provided for comfort and outside ambulation, but full weight bearing without a shoe in the household is encouraged immediately to prevent joint stiffness. The patient is encouraged to use a heel to toe gait and not walk on the side of their foot. The patient is instructed in passive dorsiflexion of the joint preoperatively, and these instructions are repeated FIGURE 19. The graft is laid on the base and sutured into place. The hemostats are not removed until the graft is secured. Volume 7, Issue 1 Copyright @ 2008 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. 37 Special Focus: Hasselman and Shields immediately postoperatively. Passive and active dorsiflexion and plantarflexion of the joint is encouraged immediately postoperatively. This early joint mobilization has not interfered with normal wound healing, and few wound complications have been seen by early mobilization of the joint. The skin suture is a running subcuticular absorbable stitch, and therefore suture removal is not needed. The patient is seen 2 weeks postoperatively, and formal physical therapy is prescribed for range of motion and strengthening as needed. No bracing is used for the hallux postoperatively to maintain alignment, and no postoperative deformities have been seen by the authors. Weight-bearing postoperative radiographs of the foot are taken at 6 weeks to ensure appropriate alignment (Fig. 20). In the study patients, postoperative radiographs are repeated at intervals according to the study protocol. | COMPLICATIONS As with any surgical procedure involving a joint, the potential complications include infection, stiffness, persistent pain, and neurological injury. With this particular technique, the most common complication has been loss of intraoperative dorsiflexion; however, the range of motion seen postoperatively even in these patients has been adequate and without activity limitation. Other complications have been local wound infections that have resolved with oral antibiotics and local wound care. A rare complication previously mentioned is the use of metallic suture anchors with the HemiCAP implant. The suture anchors contacted the implant, and a metallosis reaction occurred that required removal of FIGURE 21. Postoperative lateral fluoroscopic view showing passive dorsiflexion of the first MTP joint with the HemiCAP in place. Note that the sesamoids glide over the implant, and dorsiflexion is at least 90 degrees in this patient. the implant and arthrodesis. Since then, bioabsorbable suture anchors have been used. Some patients complained of mild to moderate plantar pain felt to be related to sesamoid pain or flexor tendonitis that resolved after 2 to 3 months. No loosening of any implants has been observed since the introduction of this new technique 30 months ago. Should this implant fail because of persistent pain, swelling, or other reasons, then surgical options include either Keller resection arthroplasty or arthrodesis. The latter could be done by either shortening the hallux and primary bone apposition using conical reamers or using a bone block interposition to maintain hallux length. | RESULTS FIGURE 20. Postoperative anteroposterior and lateral radiographs of the patient seen in Figure 2. Note that the implant has resurfaced the damaged metatarsal head. Alignment is restored. This patient has returned to normal activities. The metallic suture anchors are no longer used for the interposition graft. 38 During the past 30 months, more than 100 patients have undergone hemiarthroplasty of the first MTP joint using the HemiCAP prosthesis at our institutions. Conditions treated included hallux rigidus, arthritic hallux valgus, failed previous osteotomies and cheilectomies, and avascular necrosis of the metatarsal head and failed fusion caused by increased pressure on the proximal phalanx. To date, in more than 100 patients, there have been 2 failures, one from infection and the other from metallosis. Twenty-five of the first 30 patients with stage II or III hallux rigidus consented to participate in a followup study. The mean age of the patients was 51 years. Occupations included carpenters, housewives, physicians, executives, and manual laborers. Patient assessment was conducted with the American Orthopaedic Foot and Ankle Society and 36-item Short-Form Health Survey Questionnaire outcome measures, physical examination, and radiographic evaluation performed preoperatively and at 1, 3, and 6 months, and 1 and 2 Techniques in Foot & Ankle Surgery Copyright @ 2008 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Special Focus: First Metatarsal Head Resurfacing in Hallux Rigidus years postoperatively. Mean follow-up was 20 months. All patients are very satisfied with their results and said that they would have the procedure performed again. The mean postoperative increase in range of motion of the joint was 42 degrees (baseline, 23 degrees; postoperative, 65 degrees). The mean American Orthopaedic Foot and Ankle Society and 36-item Short-Form Health Survey Questionnaire scores were 82.1 and 96.1, respectively. These results suggest that short-term outcomes with this technique are as good as or better than other joint-sparing techniques. | CONSIDERATIONS AND FUTURE DIRECTION The HemiCAP prosthesis, as the first metatarsal head resurfacing implant, is a novel approach to the treatment of arthritis of the first MTP joint. All other hemiarthroplasty implants have resurfaced the phalangeal base. Quite often, pain and stiffness, although lessened, still persist with proximal phalanx implants.12,13 Our experience with the HemiCAP implant to date revealed superior postoperative range of motion and pain reduction when compared with the other implant hemiarthroplasties (Fig. 21). One possible explanation is that hallux rigidus pathology and cartilage loss is primarily found on the metatarsal head, and by resurfacing this side, the damaged cartilage is removed and a smooth and congruent new joint surface is created. Furthermore, impaction of the proximal phalanx on the metatarsal head is thought to be a major etiologic factor in the development of hallux rigidus. Hemiarthroplasty techniques that resurface the proximal phalanx base still leave damaged metatarsal cartilage. The impaction of the implant onto the remaining damaged metatarsal head could be a leading cause for persistent pain with those implants. Metatarsal head resurfacing may therefore explain further improvement in postoperative pain relief. There have been no reports of implant loosening or osteolysis around the HemiCAP implant to date. In contrast, studies on phalangeal-sided hemiarthroplasty report loosening of the implant as a significant problem even with short-term follow-up.12,13 It is possible that the shear stresses seen in the proximal phalanx with repetitive dorsiflexion cause the implant to loosen or prevent proper bony ingrowth early on. Historically, the phalangeal component of metallic implants that resurface both sides of the joint has been prone to loosen. The metatarsal side does not see the shear stresses on the boneimplant interface, which may explain improved fixation and osseous integration. Further studies are needed to explore this possibility. In addition, the high-pitched screw fixation component may provide a stronger con- struct than traditional keeled or pegged cementing techniques. It is because of this novel implant design that we think this implant works well even in the conditions of repetitive stresses. Some patients have been recreational runners. Although no professional athletes have been done, to our knowledge, we feel that this implant could withstand the impact and repetitive stresses of a professional football player. The treatment focus of Berlet et al10 is similar to that of HemiCAP implantation by targeting metatarsal head pathology. In both techniques, preliminary results demonstrate similar postoperative range of motion, pain relief, and patient satisfaction while avoiding postoperative deformities, transfer metatarsalgia, or push-off weakness. It seems that addressing the metatarsal surface may provide better results when treating hallux rigidus. Although it should be remembered that both techniques have only preliminary results, and longer follow-up is needed to determine the durability of each treatment option. The HemiCAP technique is minimally invasive, with only subchondral bone resection needed for its implantation. Viable bone stock is therefore preserved, and future treatment options including joint fusion are maintained should the condition require further intervention. In summary, the use of the HemiCAP implant to resurface the metatarsal head in hallux rigidus has shown very promising short-term results. Longer follow-up is needed to determine the durability of this implant and long-term functional outcomes. Future studies to determine the optimal technique for addressing coexisting phalangeal involvement are also needed. | REFERENCES 1. Brage ME, Ball ST. Surgical options for salvage of endstage hallux rigidus. Foot Ankle Clin North Am. 2002;7: 49Y73. 2. Gianini S, Ceccarelli F, Faldini C, et al. What’s new in surgical options for hallux rigidus? J Bone Joint Surg Am. 2004;86A:72Y83. 3. Mann RA, Clanton TO. Hallux rigidus: treatment by cheilectomy. J Bone Joint Surg Am. 1988;70A:400Y406. 4. Mulier T, Steenwerckx A, Thienpont E, et al. Results after cheilectomy in athletes with hallux rigidus. Foot Ankle Int. 1999;20:232Y237. 5. Moberg E. A simple operation for hallux rigidus. Clin Orthop Relat Res. 1979;142:55Y56. 6. Thomas PJ, Smith RW. Proximal phalanx osteotomy for the surgical treatment of hallux rigidus. Foot Ankle Int. 1999;20:3Y12. 7. Cleveland M, Winant EM. 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