The Poetry of Osseointegration

By Phil Stevens, MEd, CPO, FAAOP

Patient-Oriented Evidence that Matters...to Patients

Over the last several years, there has been a steady escalation of interest in and research associated with the use of osseointegration (OI) as a means of managing unilateral transfemoral amputations. Much of the research has focused on the viability of the boney attachment or abutment. Can it be implanted safely? Will it loosen over time? Will infection rates be manageable? While these questions-and the research that helps to answer them-are undoubtedly important, a number of studies have also included considerations that are more immediately relevant to current and prospective OI patients: Will it improve my overall comfort? Will it improve my functionality? And the more nebulous, question: How have other patients responded to the treatment?

This article provides an overview of recent literature findings pertaining to OI, with an emphasis on the evidence that seems to matter the most to patients, and more specifically, to those patients who would consider undergoing OI procedures.

As the U.S. Department of Veterans Affairs (VA) continues its analysis about how and to what extent OI treatment approaches will ultimately be used in the care of its service members with amputations, Webster et al. performed a study to better understand why existing amputees would be willing to undergo the procedure.1 Following a detailed explanation of the procedure and a description of the potential advantages and disadvantages, the researchers found that only one-third of patients currently living with a lower-limb amputation would consider OI.

Taking a closer look at why these individuals said they would consider OI provides a better understanding of what potential patients view as the most important possible benefits of the procedure (See table at right).1 Some of these perceived advantages, like "easy and quick attachment" and "secure attachment and suspension," are based on inherent mechanical realities. Other percieved advantages including "improved prosthetic function," "improved walking ability," and "improved activity level and lifestyle," are more complex and require scrutiny post-OI to better understand if they were achieved. Fortunately, recently published findings provide insight into these three highly anticipated benefits.

Improved Prosthetic Function

In 1999, a team in Sweden began Osseointegrated Prostheses for the Rehabilitation of Amputees (OPRA), a clinical trial of a newly standardized rehabilitation process for patients undergoing OI procedures. One of the early reports from the OPRA trial included findings on its first 18 patients at their two-year follow-up appointments.2 The researchers reported on the findings of an established measurement tool, the Questionnaire for Persons with a Transfemoral Amputation (Q-TFA). This survey instrument was developed for patients with transfemoral amputations and informs upon such variables as usage, mobility, problems, and overall well-being. Although the concept of "prosthetic function" is a broad one, the reported scores on the Q-TFA seem to capture much of what might be included in this domain.

Usage was documented using the "Use" score on the Q-TFA in which a daily usage of 15 hours per day was equated with a maximum score of 100 points. Patients who wore their prostheses for fewer than 15 hours per day or fewer than seven days per week were assigned lower scores. For example, a patient who wore his prosthesis for eight hours a day, seven days a week, would score a 52, while a patient who wore his prosthesis for six hours per day, five days a week, would score a 23.

The pre-OI scores were tremendously variable, ranging from 0 to 100 with a mean of 51. This is consistent with the usage rates commonly seen in clinical practice in this population. At the two-year follow-up appointment, the mean use score had increased to 83. One of the 18 subjects who was experiencing pain and loosening of the implant was not using a prosthesis. Among the remaining 17 subjects, all but one reported daily prosthetic use. Half of the 18 subjects reported more than 15 hours of use per day. Three participants reported usage rates of 13-15 hours per day, and five subjects reported less than 12 hours per day.2

The authors specifically pointed out that challenges resulting in occasional disuse of the prosthesis continued to manifest for many patients. Preoperatively, one-third of the patients who were using a prosthesis reported the need to refrain from using it for a period of time because of a poor socket fit, skin problems, or phantom pain. Similarly, at the two-year follow up, roughly one third (6 out of 17) reported the need to refrain briefly from use of the OI prosthesis because of pain, infection, or broken components.2

Within the metric of Prosthetic Mobility, the authors could only report on the 14 subjects who were using a prosthesis both pre-operatively and at the two-year follow up. Within this cohort, mobility scores increased by an average of 17 points. Improvements in the individual "mobility" sub-scores were as follows, bearing in mind that each is measured on a scale of 0 to 100: Use of a walking aide (an upper-limb assistive device needed for either indoor and outdoor walking) decreased a modest six points. Capability (reported ability to navigate environmental obstacles and certain activities of daily living) demonstrated a more striking increase from 60 to 88 points. Walking habits (reports of daily walking distances) also improved from 39 to 57 points.2

Taken in sum, preliminary observations of the OPRA study found that prosthetic function largely improved for these patients. While problems with pain and infection had a modest and infrequent impact on prosthetic use, these hindrances were not unlike those experienced with socket prostheses. The OI prostheses were reportedly used much more throughout the day and more days per week than the traditional prostheses. While the reliance on upper-limb assistive devices was minimally reduced, subjects reported more substantial improvements in what they were able to do and the distance they were able to walk each day.2

Improved Walking Ability

As more patients undergo OI procedures, more evidence will emerge; however, the published observations to date suggest that while the general concept of "walking ability" may improve, gait asymmetries and challenges seen prior to OI may persist in its wake. In a more recent report on 100 OI cases, Hagberg et al. stressed the importance of patients understanding the limitations of the intervention.

"The patient must be given a realistic picture of mobility outcomes... [P]atients must be aware that walking might still require walking support and that the gait pattern might not significantly change."3

These observations, based on the Swedish experience, are remarkably similar to the observations of Sullivan et al. in their report on the preliminary British experiences. They also cautioned that patients should be made aware that gait deviations may persist following OI: "Potential candidates approaching osseointegration wishing to improve their gait pattern may be disappointed. An indication of a candidate's post-osseointegration gait patterns is the pre-osseointegration gait using a socket prosthesis... If lateral trunk bending is apparent pre-osseointegration, it is likely to be present post-osseointegration, possibly more pronounced."4

"Improvements in gait pattern should not be the main motivating factor for candidates considering the procedure, but the implications and issues surrounding this aspect of osseointegration need to be discussed and fully understood by the candidate to avoid disappointment later."4

The fact that nearly 90 percent of the VA survey respondents who stated that they were willing to consider OI indicated the objective of "improved walking ability" as a part of their rationale for doing so underscores the importance of educating potential OI candidates about the limitations that have been observed to date as well as the need to continue monitoring this variable in the emerging literature.

Improved Activity Level and Lifestyle

The "activity level" metric overlaps somewhat with "prosthetic function," which was discussed above. Comparing pre-OI activity levels with post-OI activity levels make the "activity level" metric relatively straightforward to quantify. However, quantifying what it means to have an improved "lifestyle" is much more subjective and difficult. While it certainly comprises numerous considerations, one means of assessing improved lifestyle is simply to ask patients the question, "How do you experience living with your osseointegrated prosthesis compared to your earlier prosthesis suspended with [a] socket?"5 This question was recently used in a series of structured interviews with established OI patients from the Swedish contingent who had at least three years of experience with an OI prosthesis. Once completed, the content of the interviews was evaluated and reduced into groupings of common sentiment and meaning. Unsurprisingly, no single dominant experience emerged to describe the sentiments of all study subjects. Instead, a series of three "typological structures" emerged. These three structures represent increasing levels of acceptance of the OI prosthesis as a part of one's self.5

Typology 1: Practical Prosthesis

While the authors reported that all subjects spoke of "revolutionary" and "radical" changes in their lives and functionality, the patient responses grouped within this typology were the least accepting of their new prostheses as a part of themselves. These patients continued to view their prostheses as tools rather than as part of their bodies. Speaking of the experience with the OI prosthesis compared to prior experience with a traditional prosthesis, one of the subjects in this group made the following representative statement: "I can feel that it's not as good as a healthy leg, but it's far more normal than the old one.... This is perhaps 70 percent as compared to a real leg...being 100 percent and an old prosthesis is perhaps 25 percent."5

Typology 2: Pretend Limb

While this group had assimilated their OI prostheses into their sense of self more so than the previous group, and seemed to see them as more than a tool, there was still a sense of uncertainty in their full acceptance, as the benefits of improved functionality were countered by a continued sense of awkwardness. The increased acceptance level is exemplified by the following representative statement from one of the respondents: "The prosthesis is a part of me since it works so well, and you don't have to think that it's a problem and that it should be hard and so forth.... It's more like a substitute, my 'pretend leg.'"5 However, the emergence of continued frustrations was also evident. In this separate statement referencing the new OI prosthesis, one respondent said, "There is something missing, one part of me is missing, and I miss it physically in a way I haven't done before, not after the accident either. And this happened after I got the prosthesis that is more me than ever, that makes me feel more whole as a person."5

These conflicting feelings are further illustrated by a third statement in which a subject spoke about the experience of using an OI prosthesis: "No, it's much more integrated than it was with this old prosthesis-it becomes a part of you. I don't know how to describe it since it's not like I'm feeling my foot in any way.... It's still a prosthesis, and that I am very much aware of-especially when I am in a bad mood."5

Typology 3: A Part of Me

The comments from the third group of patients reflected feelings of a new "wholeness" characterized by complete acceptance of and trust in their prostheses. Responses from this group can be characterized by the following statement: "I don't think about having the prosthesis in that it doesn't feel like a prosthesis. With this kind of technology, you can't feel it."5 While patients in this group described no longer feeling the socket of the prosthesis, they also described the sensations of being able to feel their environment through the OI prosthesis: "It's very concrete, as opposed to a traditional prosthesis that is slipped onto the outside of the body," one subject said. "But here I can feel when I put the foot down, so that I can feel the shock throughout the body-not in an unpleasant way but I feel it, and it gives me a positive experience of my body as a whole."5

Taken as a group, the responses from this interview process begin to address the nebulous idea of the experience of living with an OI prosthesis. There was no single unifying experience, with some patients continuing to view the prosthesis as an external tool and others reporting a more holistic acceptance. Importantly, however, the responses were almost universally positive, and the anticipated benefit of an "improved lifestyle" appears to be supported by the documented experiences with OI.

Summary

The findings of the VA study described at the beginning of this article identify benefits that appear to be of most value to patients who would consider OI. These benefits include function, ability, activity level, and lifestyle. To the extent that these benefits have been studied, there is emerging evidence that many of these goals are obtainable following OI. Improvements in usage and capabilities have been documented, along with generally positive perceptions associated with living with an osseointegrated prosthesis. However, study authors have also cautioned against the assumption that OI will address certain gait deficits or reduce dependence on upper-limb assistive devices. The observations made in these preliminary studies provide a good insight into how well the OI experience has measured up to the anticipated benefits among prospective patients.

Phil Stevens, MEd, CPO, FAAOP, is in clinical practice with Hanger Clinic, Salt Lake City, Utah. He can be reached at

References

  1. Webster J., T. Chou, M. Kenly, M. English, T. Roberts, and R. Bloebaum. 2009. Perceptions and acceptance of osseointegration among individuals with lower limb amputations: a prospective survey study. Journal of Prosthetics and Orthotics 21(4):215-22.
  2. Hagberg K., R. Branemark, B. Gunterberg, and B. Rydevik. 2008. Osseointegrated trans-femoral amputation prostheses: Prospective results of general and condition-specific quality of life in 18 patients at 2-year follow-up. Prosthetics and Orthotics International 32(1):29-41.
  3. Hagberg K. and R. Branemark. 2009. One hundred patients treated with osseointegrated transfemoral amputation prostheses-Rehabilitation perspective. Journal of Rehabilitation Research & Development 46(3):331-44.
  4. Sullivan J., M. Uden, K. P. Robinson, and S. Sooriakumaran. 2003. Rehabilitation of the trans-femoral amputee with an osseointegrated prosthesis: The United Kingdom experience. Prosthetics and Orthotics International 27(2):114-20.
  5. Lundberg M., K. Hagberg, and J. Bullington. 2011. My prosthesis as a part of me: A qualitative analysis of living with an osseointegrated prosthetic limb. Prosthetics and Orthotics International 35(2):207-14.