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Outcomes from the Surgeon's Perspective

Michael S. Pinzur, MD

THE NEW PARADIGM

One of the greatest challenges currently facing modern medicine is the shift in the paradigm from experience- based decision-making to evidence-based decision- making. Concurrent with the necessity for clinical algorithms based on objective data has been the development of the "outcomes movement."^1–3 Very simply stated, results are the subjective and objective measures that we, as healthcare professionals, use to measure our interventions. The goal of the outcomes movement is to create objective numerical "scores" from the subjective impressions that patients perceive on how their disease or injury process affects their quality of life. This process is accomplished by using specially designed questionnaires and social science statistical methods to convert the subjective impressions or feelings of the target focus group into objective numerical scores. Although not specifically accurate for an individual patient, these social science instruments attempt to provide objective population data related to the impact of disease or injury on the healthrelated quality of life for specific or generalized patient populations.

BENCHMARKING

The first step in the process is the establishment of baseline information from which one can measure either the natural history of the disease or injury process or the effect imparted by a therapeutic intervention. This baseline information is understood as the benchmark. There are several nonspecific quality-of-life instruments/questionnaires that measure the generalized impact of disease or injury. The data obtained from these instruments provide generalized population norms that allow comparison between various disease or injury states. The most widely used of these generalized measures of disease impact is the SF-36.⁴ Other widely used generalized measures of disease impact are the Sickness Impact Profile (SIP),⁵ and the Western Ontario and McMaster University Osteoarthritis Index (WOMAC).⁶ These instruments can be very helpful, but only when applied in an appropriate context. To be appropriate, the questionnaire must answer the question that is being asked, that is, be responsive. It must also be able to accurately measure change over time, or following intervention, that is, be discriminative.

One must also take into account the "floor" and "ceiling" effects of specific instruments when used for specific patient populations. Patients with Charcot foot arthropathy fare so poorly on generalized quality-of-life instruments that a measurable change after intervention will not be detectable.⁷ This is known as a floor affect. To measure a detectable improvement after therapeutic intervention, one needs to use a specific instrument that is capable of measuring both positive and negative change over time. A ceiling effect occurs when the focus population functions at a level that exceeds the measuring ability of the instrument. This effect was observed in the early energy consumption studies of young traumatic amputees, where very little effect could be measured when the subjects were simply asked to walk on a level surface for a short distance.⁸

THE PROSTHETIC EVALUATION QUESTIONNAIRE

The Prosthetic Evaluation Questionnaire (PEQ) is a validated social science quality-of-life instrument that was specifically designed to measure the impact of a lower extremity amputation on the prosthetic-associated quality of life of affected individuals. As such, the original validation data published by Legro et al.⁹ was difficult to interpret, as the study population was composed of subjects of diverse age, underlying cause for amputation, and amputation level. The data obtained revealed that the instrument was capable of discerning quality-of-life impact related to the amputation and to life with a prosthesis, yet it gave us very little generalizable disease-specific information. The information gleaned from instruments such as this only affects surgical decision-making when it is used in the specific focus population that is being assessed.

Harness and Pinzur¹⁰ specifically applied this instrument to a group of dysvascular transtibial amputees with an average age of 68 years. By specifically selecting a focus group that commonly requires transtibial amputation, valuable prognostic insight was obtained that could be directly applied to patient care and surgical decision-making in this common patient population. Although experienced experts in the care of diabetic and dysvascular transtibial amputees would expect patients to score highest in the function and mobility domains and lowest in the psychosocial areas, the converse was actually determined.¹⁰

Another belief held by experts was the mistaken assumption that quality of life and functional performance would somehow be directly related. There was no correlation between performance testing and outcome perception when a small group of transtibial amputees was studied. Apparently, an elderly individual capable of doing only limited walking might be "happy" because even this limited walking capacity enabled the individual to live independently. This was in contradistinction to a younger, more active amputee who functioned reasonably well but felt a severe negative impact on quality of life due to what appeared to be a relatively minor functional disability.¹¹

Bone bridging in transtibial amputation is possibly the most controversial current topic in amputation surgery. Its supporters sometimes view the technique with much enthusiasm yet there is no objective scientific evidence to support a surgical procedure with increased potential surgical morbidity compared with standard transtibial amputation.¹² To gain insight, the questionnaire was translated into Portuguese and was completed by a consecutive group of Brazilian patients of various ages and underlying causes for amputation, ranging from trauma to diabetic infection. An arbitrary control group was established from highly functional independent amputees from two centers in the United States who were simply returning for prosthetic checkup. In spite of the fact that the bone-bridge group was a consecutive series of "all-comers" and compared with a very functional successful group in the control population, in many respects, the patients with bone bridge outperformed the traditional group.¹³ This study had several limitations, many being related to the comparison between disparate cultures, but it did provide some quasi-objective data to support further interest in the bone bridge.

DECISION-MAKING IN LOWER EXTREMITY AMPUTATION

How does this understanding of outcomes affect our surgical decision-making? Amputation of a lower extremity is performed for many reasons by surgical generalists or specialists of many disciplines. We frequently face the question of therapeutic intervention to affect limb reconstruction versus amputation. The decision-making process is identical, irrespective of the underlying cause for amputation. Four issues must be addressed before initiating treatment, whether addressing a mutilating limb injury, diabetic foot infection, gangrene, or proximal focal femoral deficiency:

(1) Will the reconstructed limb outperform an amputation and prosthetic fitting? If all transpires as one can reasonably expect, will the functional independence of the patient be best served after reconstruction or with amputation?

(2) What is a realistic expectation of the functional independence of the patient if the reconstruction is successful? What is a realistic expectation of the patient's ability to walk with a prosthesis? One must remember that each and every patient will not achieve the best functional result that the surgeon has ever obtained. Most patients will fall within 1 standard deviation of the average for the disease or injury in question.

(3) What are the costs? The most obvious costs are financial. One must also consider whether the patient can afford the time commitment required for limb reconstruction, in addition to the cost of care and time unable to work. Many trauma surgeons have witnessed patients who have lost their job during the period of treatment, exhausted their financial reserves, and divorced their spouse.

(4) What are the risks? Can the patient tolerate the many and prolonged surgeries and anesthetics associated with limb reconstruction?

Before initiating treatment, the surgeon should have reasonable answers for each of these questions. It is then incumbent to learn the relative values and associated risks that the patient will accept in each of these domains. With a knowledge of real expectation, the enlightened outcomeoriented surgeon is then able to apply modern techniques to optimize prosthetic fitting and rehabilitation.

BEST PRACTICE TECHNIQUES

There is virtually no evidence to support specific surgical techniques in lower extremity amputation surgery. The following methods are the consensus best practice techniques used in the United States today:

The most functional lower extremity major limb amputation is the Symes ankle disarticulation. This level allows direct load transfer, that is, end-bearing. This level is easily accommodated in patients with major volume fluctuation by using a volume-adaptable prosthesis. Patients generally maintain their walking independence with a minimal increased energy cost of walking. Patients rarely require hospitalization on a rehabilitation unit and require minimal physical therapy.^14,15

The long posterior myocutaneous flap technique popularized by Burgess et al.¹⁶ is the accepted standard surgical technique to optimize load transfer. The bone bridge technique has been touted to enhance load transfer.¹² Although its proponents support it with sometimes religious zeal, there is very limited level IV anecdotal evidence to justify the increased potential morbidity.¹³ Evidence-based medicine methods are going to be required to determine its relative value. The length of the residual limb should be the maximum length that will allow adequate soft-tissue cushioning of the terminal residual limb. Assal et al.¹⁷ have suggested that an extended posterior flap is beneficial to cushion the anterior-distal tibial area during weightbearing. Although simply empiric, there appears to be no downside risk in patients with available soft tissues.

Knee disarticulation using a posterior myocutaneous flap to act as a weightbearing cushion is greatly underutilized.¹⁸ This level is intrinsically stable during stance phase, when the prosthesis incorporates a four-bar linkage prosthetic knee joint. Patients appear to be more functionally independent and have a decreased metabolic cost of walking as compared with transfemoral amputation.¹⁹ This level should be avoided when the gastrocnemius muscle is not available to act as a weightbearing cushion.²⁰

The adductor-based long medial myocutaneous flap of Gottschalk²¹ appears to greatly enhance walking function in transfemoral amputees. By engaging the femur, the "adductor lurch" limp of gait is greatly decreased. The adductor "roll" is eliminated by maintaining the length of the adductor muscles.

CONCLUSIONS

The goal of conferences such as this is to change our current experienced-based paradigm for surgical decision-making to a process that is predicated by evidence. The steps of our decision-making algorithm should each be guided on reasonable expectations of the result/outcome at the conclusion of treatment.

Correspondence to: Michael S. Pinzur, MD, Loyola University Medical Center, 2160 South First Avenue, Maywood, IL 60153; e-mail: .

MICHAEL S. PINZUR, MD, is Professor of Orthopaedic Surgery & Rehabilitation, Loyola University Medical Center, Maywood, Illinois.

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