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Subtalar Joint Compensation after Ankle Fusion

Ankle fusion continues to be a predictable treatment for degenerative tibiotalar arthritis. It improves both pain and function from primary osteoarthritis and degeneration related to chronic instability or trauma. JBJS has published several recent studies demonstrating that the outcomes of fusion compare favorably with those of total ankle replacement, particularly in higher-demand patients. (See, for example, Effectiveness and Safety of Ankle Arthrodesis Versus Arthroplasty and Outcomes of Total Ankle Replacement, Arthroscopic Ankle Arthrodesis, and Open Ankle Arthrodesis for Isolated Non-Deformed End-Stage Ankle Arthritis.)

Many clinicians have wondered why outcomes after ankle arthrodesis are typically so much better than those after arthrodesis of other mobile joints. In the April 1, 2020 issue of The Journal, Lenz et al. provide an answer. Using dual fluoroscopy integrated with 3-D CT, the authors compared the subtalar motion of the surgically fused ankle in 10 patients with the motion of the untreated, asymptomatic side. The findings strongly suggest that compensatory increased plantar flexion of the subtalar joint allows improved function following successful arthrodesis. The authors found that this increased motion occurred during both normal plantigrade ambulation and bilateral heel raises.

Clinicians can use this important information to explain to patients who are deciding between ankle arthrodesis and arthroplasty how fusion can not only improve pain, but can also result in good functional range of motion. On the other hand, the authors surmise that the compensatory increase in subtalar joint plantar flexion may explain the reported increased risk of future subtalar osteoarthritis in surgically fused ankles. However, to answer that question, we’ll need larger, longitudinal clinical studies that evaluate the relationship between the compensatory post-fusion subtalar kinematics discovered by Lenz et al. and radiographic findings and patient-reported pain and function.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

Implant Prices are Main Cost Driver in Joint Replacements

Orthopaedic surgeons have long been aware of the role that implant prices play in the total cost of care for arthroplasty procedures, but methodical breakdowns of implant costs in relation to the cost of other aspects of care have generally been lacking. In the March 4, 2020 issue of The Journal, Carducci et al. detail the impact of implant costs on the total cost of care in a study of 6 lower- and upper-extremity arthroplasty types performed at a single, high-volume orthopaedic specialty hospital.

Using a uniform method called time-driven activity-based costing, the authors calculated the total costs of >22,200 inpatient primary total joint arthroplasties, and then broke down those total costs by categories, including implant price and personnel costs. It was no surprise that, as a percentage of total cost, implant costs were highest for low-volume surgeries (as high as 65% for total ankle arthroplasty) and lowest for high-volume procedures (e.g., 40% for total knee arthroplasty). Nevertheless, across the board, implant price was the most expensive component of total cost.

Implant prices are individually negotiated between a hospital and an implant supplier and are usually protected by nondisclosure agreements, so the data from this investigation may not match up with data from any other institution. Unfortunately, the future of implant-cost research will be tied to the complex issue of return-on-investment for implant-manufacturer stockholders as it relates to negotiations with individual hospitals and health systems.

The profound impact of implant price on the total cost of all the joint arthroplasties studied by Carducci et al. also begs the questions as to how “generic” implants (those not manufactured by the major orthopaedic producers) will ultimately influence the market—and whether “branded” implants, with their 30% to 50% markups, provide any functional benefit for patients. We will need further well-designed research to address those questions.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

Total Ankle Arthroplasty: Maybe Not as Finicky as We Thought?

As the orthopaedic community continues to solve complex issues related to joint replacement, it has become apparent that deformity correction and component positioning are keys to long-term success. In terms of hip, knee, and shoulder arthroplasty, we have progressed throughout the last 50 years with improved functional outcomes and component longevity. Elbow arthroplasty development has lagged somewhat because indications for that procedure are much less common.

Meanwhile, total ankle arthroplasty (TAA) experienced a short-lived decade of enthusiasm in the late 1970s and early 1980s before it became apparent that improved component designs and surgical techniques were needed. Progress with TAA stalled until the late 1990s, but TAA has now become more predictable, and several successful designs are available with reasonable revision rates demonstrated during 10-plus years of follow-up. As with all arthroplasties, component alignment in TAA is critical, and we have therefore assumed that significant preoperative frontal plane deformity is a contraindication for this procedure.

However, in the December 18, 2019 issue of The Journal, Lee et al. challenge that assumption with midterm follow-up data on 146 TAAs that suggest patients with frontal plane deformities >20° should not necessarily be disqualified from having this procedure. In this study, prior to surgery, 107 ankles had moderate frontal plane deformity (5° to <15° of varus or valgus) and 41 ankles had severe deformity (>20° to 35° of varus or valgus). The authors found no difference between these groups in terms of functional outcomes, complications, or implant survival at a mean follow-up of 6 years. Lee et al. conclude that frontal malalignment >20° in patients with end-stage ankle osteoarthritis may not be a contraindication to proceeding with TAA. However, the authors emphasize that concomitant realignment procedures at the time of index arthroplasty (including ligament releases and corrective osteotomies) were much more common in the severe group.

These findings need confirmation from other groups and with longer-term follow-up so that data from lower-volume surgeons can be analyzed and later complications can be investigated. Still, it just may be that ankle arthroplasty is not as finicky as we have been thinking.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

Negative Findings from Level-I Trial Still a Step Forward

Donor-site morbidity from harvesting autologous bone graft has driven the decades-long search for a substitute that performs at least as well as a patient’s own bone. Much of the clinical research on donor-site morbidity is flawed by detection bias, but other factors such as operating-room time and expense are still driving the search for the ideal substitute for autologous bone. Still, the discovery of an ideal bone-graft substitute continues to be elusive.

In The November 6, 2019 issue of The Journal, Myerson et al. report findings from a Level-I trial that investigated the use of adipose-derived cellular bone matrix (ACBM) as a graft substitute in patients undergoing subtalar arthrodesis. Among 57 patients who received autograft and 52 who received ACBM, the substitute delivered lower fusion rates as determined by both CT and plain radiographic/clinical evaluations at 6 months. In addition, patients treated with autologous bone graft had lower rates of serious adverse events.

I commend the authors and funders (AlloSource) of this well-designed clinical trial for reporting these negative results, because it is often just as important to know what doesn’t work as what does. (This manuscript was submitted even after AlloSource decided to halt further production of its ACBM product in 2017.) Such transparent reporting saves other investigators and graft substitute-focused companies from going down similar avenues of investigation. Perhaps even more importantly, publishing negative results such as this might save patients from undergoing procedures with similar formulations that would probably have minimal chance of helping and could do harm.

By contributing to the scientific “process of elimination,” this study brings us one step closer to the identification of a worthy substitute for autologous bone graft.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

Subtalar Joint’s Middle Facet Yields Insight into Flatfoot

Many foot and ankle surgeons would relish a simple measurement made from a readily available imaging modality to help detect whether patients with adult acquired flatfoot deformity (AAFD) are at high risk for progressive collapse—and to help them with surgical planning. According to the findings from a case-control study by de Cesar Netto et al. in the October 16, 2019 issue of The Journal of Bone & Joint Surgery, that wish may soon be realized.

The authors made standing, weight-bearing computed tomography (CT) scans of 30 patients with stage-II AAFD (mean age of 57.4 years) and 30 matched controls (mean age of 51.8 years). From those images, 2 fellowship-trained surgeons, who were blinded regarding the patient cohorts, measured the amount of subluxation (percentage of uncoverage) and the incongruence angle of the middle facet of the subtalar joint in the coronal plane. The authors found substantial to almost perfect intraobserver and interobserver reliability for both measurements.

Based on these middle-facet measurements, the mean value for joint uncoverage in patients with AAFD was 45.3% compared with 4.8% in controls. Similarly, the mean incongruence angle in the AAFD group was 17.3° in the AAFD group and 0.3° in controls. Further analysis led the authors to conclude that “an incongruence angle of >8.4° and an uncoverage percentage of 17.9% were found to be highly diagnostic for symptomatic stage-II AAFD.”

De Cesar Netto et al. say the biomechanics of the subtalar joint made focusing on the middle facet a sensible approach, and they attributed the high reliability of the measurements to the relatively simple anatomy of the middle facet. Still, because clinical outcomes were not assessed in this study, the role of the middle facet as a marker of peritalar subluxation and a tool for deformity correction in AAFD patients needs further investigation in prospective, longitudinal studies.

Step Monitors Yield New Insight into Ankle Surgery Outcomes

Patients considering surgery for end-stage ankle arthritis often ask which  treatment—arthroplasty or arthrodesis—will help the most. Findings from various studies attempting to answer that complex question have been equivocal. In the July 3, 2019 issue of The Journal of Bone & Joint Surgery, Shofer et al. inject some objective data gleaned from step counters worn by 234 patients into this predominantly subjective question.

All patients were treated with either arthroplasty (n = 145) or arthrodesis (n = 89). Their step activity was measured with a StepWatch 3 Activity Monitor preoperatively and at 6, 12, 24, and 36 months postoperatively. In both groups combined, step counts during “high activity” (>40 steps per minute) increased by 46% over 36 months. At 6 months, the mean high-activity step improvement was 194 steps in the arthroplasty group, compared with a mean decline of 44 steps for the arthrodesis group. However, by 36 months after surgery, the between-group differences in high-activity steps had disappeared.

The authors also analyzed associations between the objective step results and 3 patient-reported outcomes (the Musculoskeletal Function Assessment and the SF-36 physical function and pain scores). Unlike the patient-reported scores, which improved dramatically in the first 6 months and then plateaued, improvements in step activity increased gradually throughout the 3-year follow-up.

The authors emphasized that during the first 12 postoperative months, the arthrodesis patients had little or no improvement in step activity, but at 3 years there were no significant differences between arthrodesis and arthroplasty patients. These findings suggest that, in this clinical scenario, an individual patient’s expectations with the pace of improvement may be a suitable topic during shared decision making conversations.

This study does not entirely reconcile previously equivocal findings regarding arthroplasty-versus-arthrodesis, but it does emphasize the substantial and sustained activity benefits that patients in both groups receive. Shofer et al. conclude that objective measurements from wearable technology “may complement patient-reported outcomes” in future longitudinal outcome studies of many orthopaedic treatments.

July 2019 Article Exchange with JOSPT

In 2015, JBJS launched an “article exchange” collaboration with the Journal of Orthopaedic & Sports Physical Therapy (JOSPT) to support multidisciplinary integration, continuity of care, and excellent patient outcomes in orthopaedics and sports medicine.

During the month of July 2019, JBJS and OrthoBuzz readers will have open access to the JOSPT article titled “Effectiveness of Foot Orthoses Versus Corticosteroid Injection for Plantar Heel Pain: The SOOTHE Randomized Clinical Trial.”

Among 103 patients with plantar heel pain who received either arch-contouring foot orthoses or a single ultrasound-guided corticosteroid injection, the injection was more effective at week 4, but the foot orthoses were more effective at  week 12. But the authors note that “the differences between the interventions did not meet the previously calculated minimal [clinically] important difference value of 12.5 points.”

What’s New in Foot and Ankle Surgery 2019

Every month, JBJS publishes a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of all OrthoBuzz Specialty Update summaries.

This month, Chad A. Krueger, MD, JBJS Deputy Editor for Social Media, selected the five most clinically compelling findings from among the 60 noteworthy studies summarized in the May 15, 2019  “What’s New in Foot and Ankle Surgery.”

Syndesmotic Injury

–In a Level-II prospective cohort study, 48 patients were reviewed 12 months after transsyndesmotic stabilization with 1 or 2 quadricortically positioned screws.1 Although malreduction of >3 mm or 15° rotation was observed in 30% of the patients, outcome scores were equivalent compared with patients in the anatomically reduced group. Age, obesity, fracture pattern, and screw configuration had no effect on functional outcomes.

Total Ankle Replacement

–A Level-II prospective cohort study compared outcomes of older-generation and newer-generation total ankle replacements (n = 170) with ankle arthrodesis (n = 103). At the 3-year follow-up, both replacement and fusion resulted in improved function and reduced pain, and a pooled comparison of all outcome scores revealed no difference between the 2 procedures. However, subset analyses showed that patients who received newer-generation implants had significantly better outcomes than those who underwent arthrodesis.

Pain Management

–A prospective study analyzing opioid utilization among 988 patients following an outpatient foot and ankle surgical procedure found that only 50% of prescribed opioids were utilized.2 Risk factors for increased opioid consumption included continuous infusion catheter or regional-block anesthesia, age <60 years, high preoperative pain levels, and surgery involving the ankle or hindfoot.

Hallux Rigidus

–Authors of a prospective multicenter series followed 80 patients who underwent a first metatarsophalangeal joint arthroplasty with a 3-component, unconstrained, cementless implant.3 They reported significant improvement in AOFAS Ankle-Hindfoot Scale scores and range of motion at a median follow-up of 11.5 years, with 91.5% implant survival at 15 years. Two patients had periprosthetic cysts on the metatarsal side and 13 patients had phalangeal cysts, but the presence of cysts did not influence clinical results. Multivariate analysis showed a correlation between reduced AOFAS scores and arthrosis of the metatarsosesamoid junction, prompting the authors to suggest that the sesamoid should be enucleated in the presence of substantial arthrosis, fracture, or chondromalacia.

Clubfoot

–Deformity recurrence following Ponseti casting is often treated surgically. However, a comparative cohort study of 35 patients found that repeat casting and bracing for recurrent clubfoot resulted in acceptable 7-year outcomes in 26 (74%) of the patients. The authors suggest that in many children repeat casting should be the first-line intervention in relapsed deformity.

References

  1. Cherney SM, Cosgrove CT, Spraggs-Hughes AG, McAndrew CM, Ricci WM, Gardner MJ. Functional outcomes of syndesmotic injuries based on objective reduction accuracy at a minimum 1-year follow-up. J Orthop Trauma.2018 Jan;32(1):43-51.
  2. Saini S, McDonald EL, Shakked R, Nicholson K, Rogero R, Chapter M, Winters BS, Pedowitz DI,Raikin SM, Daniel JN. Prospective evaluation of utilization patterns and prescribing guidelines of opioid consumption following orthopedic foot and ankle surgery. Foot Ankle Int.2018 Nov;39(11):1257-65. Epub 2018 Aug 19.
  3. Kofoed H, Danborg L, Grindsted J, Merser S. The Rotoglide™ total replacement of the first metatarso-phalangeal joint. A prospective series with 7-15 years clinico-radiological follow-up with survival analysis. Foot Ankle Surg.2017 Sep;23(3):148-52.

Risk Factors for Persistent Opioid Use after Bunion Surgery

OrthoBuzz has previously reported on studies examining the narcotic-prescribing patterns of foot and ankle surgeons. New findings published by Finney et al. in the April 17, 2019 issue of The Journal of Bone & Joint Surgery strongly suggest that the single most powerful and modifiable risk factor for persistent opioid use after bunion surgery was the opioid dose perioperatively prescribed by the surgeon.

The authors analyzed a US private-insurance database to identify >36,500 opioid-naïve patients (mean age, 49 years; 88% female) who underwent one of three surgical bunion treatments. Among those patients, the rate of new persistent opioid use (defined as filling an opioid prescription between 91 and 180 days after the surgery) was 6.2%, or >2,200 individuals. The authors found that patients who underwent a first metatarsal-cuneiform arthrodesis were more likely to have new persistent opioid use, compared with those who received a distal metatarsal osteotomy, which was the most common procedure performed in this cohort. Additional findings included the following:

  • Patients who filled an opioid prescription prior to surgery were more likely to continue to use opioids beyond 90 days after surgery.
  • Patients who resided in regions outside the Northeastern US demonstrated significantly higher rates of new persistent opioid use.
  • The presence of medical comorbidities, preexisting mental health diagnoses, and substance-use disorders were associated with significantly higher new persistent opioid use.

However, physician prescribing patterns had the biggest influence on new persistent opioid use. A total prescribed perioperative opioid dose of >337.5 mg (equivalent to approximately 45 tablets of 5-mg oxycodone) was the major modifiable risk factor for persistent opioid use in this cohort. The authors also pointed out that 45 tablets of 5-mg oxycodone “is a relatively low amount when compared with common orthopaedic prescribing patterns” (see related JBJS study).

As orthopaedic surgeons in all subspecialties rethink their narcotic-analgesic prescribing habits, they should remember that regional anesthesia and non-opiate oral pain-management protocols have had a positive impact on pain management while minimizing narcotic use. The smallest dose of opioids for the shortest period of time seems to be a good rule of thumb.

Microbiomes, OA, and Diabetic Foot Ulcers

This post comes from Fred Nelson, MD, an orthopaedic surgeon in the Department of Orthopedics at Henry Ford Hospital and a clinical associate professor at Wayne State Medical School. Some of Dr. Nelson’s tips go out weekly to more than 3,000 members of the Orthopaedic Research Society (ORS), and all are distributed to more than 30 orthopaedic residency programs. Those not sent to the ORS are periodically reposted in OrthoBuzz with the permission of Dr. Nelson. 

We hear the term “microbiome” with increasing frequency nowadays. Merriam-Webster’s online dictionary defines it as “a community of microorganisms (such as bacteria, fungi, and viruses) that inhabit a particular environment and especially the collection of microorganisms living in or on the human body.” Two recent studies suggest how the microbiome can affect musculoskeletal health.

Incorporating the term “the arthritis of obesity,” Rochester, New York researchers1 used obese mice with trauma-induced knee osteoarthritis (OA) to provide evidence that there is a “gut-joint connection” in the OA degenerative process. After supplementing the diets of some of the mice with oligofructose (a prebiotic fiber), the authors found reduced systemic inflammation, reduced obesity-associated macrophage migration to the synovium, and suppressed obesity-induced joint-structure changes.

Another recent study investigated the on-body microbiome as it relates to diabetic foot ulcers (DFUs). Despite clinical signs and nonspecific biomarkers of infection, there is no specific and sensitive measure available to monitor or prognosticate the success of foot salvage therapy (FST) in patients with DFUs. These investigators hypothesized that the initial microbiomes of healed versus nonhealed DFUs are distinct and that the changes in the DFU microbiome during FST are prognostic of clinical outcome.2

Twenty-three DFU patients undergoing FST had wound samples collected at 0, 4, and 8 weeks following wound debridement and antibiotic treatment. Eleven ulcers healed and 12 did not. Healed DFUs had a larger abundance Actinomycetales and Staphylococcaceae (p < 0.05), while nonhealed ulcers had a higher abundance of Bacteroidales and Streptococcaceae (p < 0.05).

In the future, assessment of the initial microbiome and monitoring changes in the prevalence of specific microbiome constituents in patients with diabetic foot ulcers may be a clinical tool for predicting treatment response to foot salvage therapy. It’s also conceivable that microbiome analysis could eventually help patients and surgeons decide between FST and amputation.

References

  1. Schott EM, Farnsworth CW, Grier A, Lillis JA, Soniwala S, Dadourian GH, Bell RD, Doolittle ML, Villani DA, Awad H, Ketz JP, Kamal F, Ackert-Bicknell C, Ashton JM, Gill SR, Mooney RA, Zuscik MJ. Targeting the gut microbiome to treat the osteoarthritis of obesity. JCI Insight. 2018 Apr 19;3(8). pii: 95997. doi: 10.1172/jci.insight.95997. [Epub ahead of print] PMID: 29669931, PMCID: PMC593113
  2. MacDonald A, Brodell JD Jr, Daiss JL, Schwarz EM, Oh I. Evidence of differential microbiomes in healing versus non-healing diabetic foot ulcers prior to and following foot salvage therapy. J Orthop Res. 2019 Mar 25. doi: 10.1002/jor.24279. [Epub ahead of print] PMID: 30908702