Functional outcome in patients treated for chronic posttraumatic osteomyelitis.
Abstract: Background: Management of chronic posttraumatic osteomyelitis remains an important challenge in orthopaedics. In this investigation, 43 patients at a large university hospital were retrospectively identified who had been diagnosed with chronic osteomyelitis at 44 sites.

Methods: Diagnosis was based on the patient's history and physical examination, laboratory values, radiological evaluation, and intraoperative specimens. Patients' charts were reviewed and follow-up was obtained on 33 patients in whom Short Musculoskeletal Functional Assessment (SMFA) questionnaires were obtained.

Results: The mean follow-up of the cohort was 21.1 months (range, 10 to 54 months). Sites involved included: tibia (55%) and femur (36%), with the remainder involving the pelvis, radius/ulna, and calcaneus. Blood, bone, or wound aspirate cultures were positive in 85%, most commonly for Staphylococcus aureus. 84% of the patients in this investigation were completely cured after a single surgical intervention, removal of hardware and a course of intravenous antibiotics. Three patients required additional surgical intervention and two remained infected. Ultimately, the cohort reached a cure rate of 94%. SMFA data revealed that patients had a dysfunction score of 53.8 and bother index of 51.5, with 50 being the normal for the general population.

Conclusion: The patients in this cohort functioned at a level less than one standard deviation below the general population. These results suggest that patients with chronic posttraumatic osteomyelitis do not function significantly below that of the normal population following eradication of their infections.
Article Type: Report
Subject: Osteomyelitis (Patient outcomes)
Osteomyelitis (Care and treatment)
Osteomyelitis (Diagnosis)
Osteomyelitis (Research)
Staphylococcus aureus (Health aspects)
Staphylococcus aureus (Research)
Authors: Egol, Kenneth A.
Singh, Jaspal R.
Nwosu, Uzoma
Pub Date: 10/01/2009
Publication: Name: Bulletin of the NYU Hospital for Joint Diseases Publisher: J. Michael Ryan Publishing Co. Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2009 J. Michael Ryan Publishing Co. ISSN: 1936-9719
Issue: Date: Oct, 2009 Source Volume: 67 Source Issue: 4
Topic: Event Code: 310 Science & research
Geographic: Geographic Scope: United States Geographic Code: 1USA United States
Accession Number: 247225909
Full Text: Chronic posttraumatic osteomyelitis (CPTOM) is an insidious, debilitating condition that represents a major management challenge for the orthopaedic surgeon. Osteomyelitis is an inflammation of bone and bone marrow, caused by a bacterial infection that can ultimately lead to death of the bone tissue. This infection can be characterized as one of three types: acute (within 2 weeks of onset), subacute (within a few months), and chronic (longstanding). The infection occurs via two common mechanisms (1): first, primary infections of the bloodstream, including spread from an alternate infectious focus, and second, they occur by direct injury, or trauma, that permits bacteria to directly reach the bone.

Much has been written about the treatment of traumatic osteomyelitis, (2-5) but there is very little published on the functional outcome of these patients. Within the realm of orthopaedic surgery, emphasis still remains on determining treatment protocols and modalities for a variety of diagnoses. It has been suggested that the current emphasis of orthopaedic clinical studies should be directed toward outcome research, which documents the effect of treatment on the health of those treated and the subsequent quality of their lives. This same perspective can be applied for treating and managing chronic conditions such as osteomyelitis. Hence, the purpose of this study was to investigate the success of treatment and long-term functional outcome of patients who presented to the senior author (KAE) with a diagnosis of CPTOM.

Materials and Methods

This retrospective study of consecutively treated adult patients, who were treated for CPTOM by a single surgeon, took place over a 7-year period. Between January 24, 2000 and March 13, 2006, 43 patients with posttraumatic osteomyelitis were referred to the senior author for treatment. Diagnosis was based on the patient's history and physical examination, which centered on the signs and symptoms of infection in the region of previous orthopaedic fracture care. Laboratory values, including baseline erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and complete blood count with differential (CBC), were obtained at baseline to aid in the diagnosis. (6) Radiographic evaluation included plain radiographs of the affected areas, as well as nuclear imaging and magnetic resonance imaging (MRI), when indicated. (7-9) Definitive diagnosis was confirmed on the basis of final intraoperative bacterial culture results; 6 patients with negative cultures had either positive radiographic studies and laboratory values or a draining sinus.

All patients underwent surgical debridement, which included the removal of any implanted hardware present, opening of the bony cortex, excision of sequestrum and nonviable tissue, and irrigation of the bone with at least 6 liters of fluid. Cultures and bony specimens were obtained at all operative settings and sent for analysis. Wounds were closed over suction drains, and an infectious disease consultation was obtained postoperatively.

Patients' diagnoses of osteomyelitis were confirmed after intraoperative biopsy demonstrated pathologic evidence of pyogenic osteomyelitis. These patients were stratified according to age, sex, occupation and employment status, and the presence of comorbid conditions. Using a clinical staging system developed by Cierny and colleagues for osteomyelitis, we were able to differentiate patients by classification. The classification system centered on the patient's immune status, degree of injury, the site of infection, and, finally, extent of bony necrosis. (10)

Baseline demographics, associated medical comorbidities, laboratory findings, operative data, and the American Society of Anesthesiologists (ASA) Classification were obtained from a chart review of their hospitalization. Demographic information, including socioeconomic status, education, and race, is often used to apply preoperative markers of long-term function. While the ASA classification may be a good indicator of long-term mortality, it has not been shown to conclusively associate to postoperative function and mobility. (11) All 43 patients were followed clinically. Patients were considered to have had a successful treatment if their laboratory values normalized or their draining sinuses closed, or both. Neither postoperative nuclear studies nor MRI was used routinely to assess response to treatment.

Operative complications or the need for additional surgeries, along with current smoking statuses, were noted. Success of treatment was based upon resolution of symptoms and normalization of laboratory values after antibiotic treatment. Patients were interviewed either in person or over the phone to assess current status and an Short Musculoskeletal Functional Assessment (SMFA) was obtained. The results of these surveys were compared to those of a healthy control population. (12) The SMFA form has been shown to be a reliable tool for assessing a patient's functional status following everyday orthopaedic procedures. Composed of both a dysfunction and bother index, SMFA scores are used to compare a patient's function with that of the general population.

A score of 50 implies a level of function consistent with that of the general population, while higher scores indicate poorer function. In this study, the majority of patients (75%) functioned at a level better than the community. While the average was less than 1 standard deviation from normal, these results suggest this cohort to be well functioning.

Results

A total of 44 patients were referred to and treated by the senior author for CPTOM. The mean age of the cohort was 47 years (range, 13 to 84 years), with 30 males and 13 females (Table 1). A treatment success rate of 86% (N = 37) was achieved during the initial hospital stay, suggesting eradication of infected tissues. These patients would eventually go on to heal and did not require further surgery. Under the guidelines of the Cierny classification system, 43 patients were stratified into various subsets, with the majority of patients (51%) falling under the 2A category (Table 2).

Operative details are listed in Table 3. Seven patients (15%) required additional soft tissue procedures following the index surgery. The mean number of surgeries for the group was 1.2 per patient, with four patients requiring additional surgical intervention to eradicate infection Staphylococcus aureus was the etiologic infectious agent most commonly identified (Table 4). Fourteen patients (32%) underwent removal of hardware during the initial debridement. Laboratory results, including WBC, ESR, and CRP, obtained at the time of diagnosis are listed in Table 5. Normal values for these labs are: WBC, 4.0 to 11.0; ESR (patient age / 2); and CRP, < 10 mg/L. Within this cohort, 23% of patients had elevated WBC, while 34% and 36% had elevated ESR and CRP values, respectively. Radiographic evaluation, including plain film, was performed on every patient; however, MRI as well as bone scan were used to aid in the diagnosis in selected cases. Radiographs showing evidence of osteomyelitis were positive in 30% (13 of 43) of the patients. MRI and bone scan, when used, exhibited higher sensitivity having positive results in 60% of MRI readings and 86% in nuclear imaging. There have been no cases of malignant transformation in this cohort to date.

Thirty-two patients (74%) were available for long-term follow-up at a mean of 21.1 months (range, 10 to 57). Of the remaining (11), eight patients had no available phone number or address, two patients died, and one returned to his country of origin. Questionnaires were administered to the 32-patients (21 males, 11 females), who were representative of the entire study sample. The mean age of the long-term study cohort was 51 years. The number of patients with follow-up for less than 1 year postoperatively was 18%, between 1 to 2 years, 33%, and greater than 2 years, 49%.

Seven patients reported persistent dysesthesia in the region of surgery. One of the three patients requiring additional surgery failed treatment entirely. This patient underwent an above-knee amputation (AKA) 11 months following the latest treatment failure and 10 years after the first diagnosis of osteomyelitis.

Overall, 97% of the patients (31/32) seen during long-term follow-up were healed from their original fractures. Two patients initially presented with fracture nonunion along with infection: one went on to have their infection eradicated but had a persistent symptomatic nonunion, while the other was seen at 18 months and had achieved eradication of infection and a fracture union.

Average SMFA scores for the general population are 50, with higher scores suggesting greater dysfunction. Subscale scores revealed a mean dysfunction score of 53.8 (range, 41.9 to 76.3) and a bother index of mean 51.5 (range, 42.6 to 73.9). These results illustrate that, on average, patients treated for CPTOM are impacted by general pain to a greater extent than the general population and are slightly less able to carry out daily living activities than the general population. The normalized scores were higher than the general population score of 50 by 0.25 of one standard deviation, suggesting no significant difference in function.

Discussion

Persistent pain, physical impairment, relapses, and the risk of malignant transformation are some of the complications of CPTOM. Sepsis, one of the life threatening sequelae associated with this condition, may occur from inadequate treatment. The purpose of this study was to investigate the functional outcome of patients with CPTOM, as well as their related morbidities. Patients were treated using a combination of both surgical debridement, as well as antibiotic treatment. While difficulty ambulating and loss of strength still caused significant morbidity, the majority of patients reported pain (average, 2.5 out of 10) as the most common complaint at the time of follow-up. Completely eradicating the infecting organism in osteomyelitis remains a difficult task. Although 20% of our patients required additional debridements, all but one patient seen during follow-up was healed of their original fractures. Using both medical and surgical interventions, 94% of the patients were cured of their original infections and no longer required antibiotic treatment.

The Cierny-Mader classification system for osteomyelitis describes four different types of osteomyelitis, types I to IV, and also the host's immune status, types A to C. The latter classification differentiates patients with normal immune status (type A), some degree of immuno-compromise (type B), and significantly depressed immune status (type C). Further classification is based on location and severity of the infectious focus: type I, medullary osteomyelitis; type II, superficial osteomyelitis; type III, well marginated cortical bone; and type IV, permeating destructive lesion (infected nonunion).

The results of the current study are comparable with a past review of 102 patients with CPTOM managed by local debridement and implantation of antibiotic beads from 1977 to 1983. (13) Cure was observed in 89.2% of the patients during the initial hospital stay; 15.7% required further debridements during the initial hospital stay, due to recalcitrant infection. Our investigation achieved a cure rate of 84% following a single surgical debridement and removal of hardware; four (10%) patients required additional intervention. Venkatesh and coworkers also noted that seven patients had late recurrences, and nine patients had to change their profession because of the disease. Eleven patients reported that the affected limb could not be used during activities of daily living. S. aureus was by far the most common pathogen, being the pathogen in over 82% of cases. Again, this organism was most common in our series as well.

In a review of 454 patients treated for osteomyelitis, Tice and associates noted a cure rate in 69.4% at time of follow-up at a mean of 27.5 months. (14) Recurrences occurred in 30.6% and required additional surgical intervention, either further debridement and bone excision or amputation. Our review of 32 patients available for long-term follow-up showed a cure rate and complete eradication of infection in 84%. The study also showed that patients experiencing six months without re-infection had a 22% chance of recurrence. More importantly, patients with a disease-free year following surgery were only 5% likely to have a recurrence.

The limitations to this study include it being retrospective in nature and the size of study sample, as compared to previous investigations. Baseline laboratory information was obtained on every patient; however, follow-up laboratory values were not recorded at every visit, thereby diminishing our reliance on laboratory values to determine eradication of infection. Although 75% of the study sample was able to reply and fill out the questionnaires, we did not obtain a baseline SMFA at the time surgery. This diminishes our ability to compare the cohort to their return to baseline health and function status. However, we used a control healthy population to assess what percentage of patients and to what degree they returned to this baseline healthy status. Patient self-assessment was the basis on which outcomes in this study were measured. However, physical exam findings due to follow-up retrieved over the phone could not be recorded and, therefore, were left out of the study.

Conclusion

Although chronic osteomyelitis complications encountered in this investigation occurred with less frequency than in other reports, the morbidity of CPTOM remains substantial. Therapeutic measures for such infections are comprised of early antibiotic administration as well as full excision and debridement of necrotic and infectious bone tissue. While early administration of antibiotics leads to the best results, much debate still exists regarding the appropriate route and duration of therapy. Patients successfully treated for CPTOM may regain normal functional status following treatment.

Disclosure Statement

The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated. Kenneth A. Egol, M.D., is an unpaid consultant to Exactech, Inc., has received institutional support from Biomet, Smith & Nephew, Stryker, and Synthes, and participates in stock ownership of Johnson & Johnson.

References

(1.) Roesgen M, Hierholzer G, Hax PM. Post-traumatic osteomyelitis. Pathophysiology and management. Arch Orthop Trauma Surg. 1989;108(1):1-9.

(2.) Carlino G, Trande P, Muratore M, et al. Chronic osteomyelitis: a new therapeutical idea. Reumatismo. 2001;53(4):309-11.

(3.) Patzakis MJ, Zalavras CG. Chronic posttraumatic osteomyelitis and infected nonunion of the tibia: current management concepts. J Am Acad Ortho Surg. 2005;13(6):417-27.

(4.) Lazzarini L, Mader JT, Calhoun JH. Osteomyelitis in long bones. J Bone Joint Surg Am. 2004;86(10):2305-18.

(5.) Lew DP, Waldvogel FA. Osteomyelitis. N Eng J Med. 1997;36(14):999-1007.

(6.) Abernethy LJ, Carty H. Modern approach to the diagnosis of osteomyelitis in children. Br J Hosp Med. 1997;58:464-8.

(7.) Tumeh SS, Tohmeh AG. Nuclear medicine techniques in septic arthritis and osteomyelitis. Rheum Dis Clin North Am. 1991;17:559-83.

(8.) Hauser R, Buess E, Hodler J. Preoperative magnetic resonance tomography in chronic osteomyelitis of the extremities. Schweiz Rundsch Med Prax. 1994 Mar 22;83(12):325-32.

(9.) Hauser R, Augustiny N. Magnetic resonance tomography in preoperative analysis of chronic post-traumatic osteomyelitis. Helv Chir Acta. 1989 Dec;56(4):553-9.

(10.) Cierny G 3rd, Mader JT, Penninck JJ. A clinical staging system for adult osteomyelitis. Clin Orthop Relat Res. 2003 Sep;(414):7-24.

(11.) Michel JP, Klopfenstein C. Hip fracture surgery: is the preoperative American Society of Anesthesiologists (ASA) score a predictor of functional outcome? Aging Clin Exp Res. 2002;14:389-94.

(12.) Swiontkowski MF, Engelberg R, Martin DP, Agel J. Short musculoskeletal function assessment questionnaire: validity, reliability, and responsiveness. J Bone Joint Surg Am. 1999 Sep;81(9):1245-60.

(13.) Venkatesh SK, Riederer B, Chhem RK, et al. Reactivation in post-traumatic chronic osteomyelitis: ultrasonographic findings. Can Assoc Radiol J. 2003 Jun;54(3):163-8.

(14.) Tice AD, Hoaglund PA, Shoultz DA. Risk factors and treatment outcomes in osteomyelitis. J Antimicrob Chemother. 2003 May;51(5):1261-8.

Kenneth A. Egol, M.D., is Chief of the Division of Orthopaedic Trauma, Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, and Professor of Orthopaedic Surgery, NYU School of Medicine, NYU Langone Medical Center, New York, New York. Jaspal R. Singh, M.D., and Uzoma Nwosu, M.D., were Research Fellows at the time of submission within the Musculoskeletal Research Center, Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, NYU Medical Center, New York. New York.

Correspondence: Kenneth A. Egol, M.D., 301 East 17th Street, New York, New York 10003; kenneth.egol@nyumc.org.
Table 1 Demographic Information

Categories             N = 43 (%)

Sex
  Male                  30 (70)
  Female                13 (30)

Age (13-84 yrs.)
  <40                   13 (30)
  41-55                 17 (40)
  >55                   13 (30)

Marital Status
  Single                13 (30)
  Married               19 (44)
  Divorced               5 (12)
  Unknown                6 (14)

Educational Status
  High School           16 (37)
  College               13 (30)
  Post-grad              3 (7)
  Unknown               11 (26)

Employment
  Employed              13 (30)
  Unemployed            10 (23)
  Disabled               9 (21)
  Retired                5 (12)
  Unknown                6 (14)

Smoking Status
  Smoker                 7 (16)
  Non-smoker            30 (70)
  Unknown                6 (14)

Table 2  Cierny Classification System

Classification     N = 44(%)

1A                   1 (2)
2A                  19 (43)
2B                   4 (11)
3A                   6 (14)
3B                   6 (14)
4A                   0 (0)
4B                   2 (4)
Unknown              6 (14)

Table 3 Operative Information

ASA Classification *     (N = 43)

  I                          2
  II                        22
  III                       13

Anesthesia *

  General                   22
  Spinal                    15

* Unknown = 6

Table 4 Site of Infection and Causative Organism

Bone Affected              (N = 44)

  Tibia                       24
  Femur                       16
  Pelvis                       2
  Radius/Ulna                  1
  Calcaneus                    1

Organism

  S. aureus                   20
  E. faecalis                  6
  P. aeruginosa                5
  S. viridians                 4
  C. pseudodipthericum         3
  Culture negative             6

Table 5 Laboratory Information

Laboratory Test     Average (Range)

WBC                  8.4 (4.2-20.8)
ESR                 60.7 (2-130)
CRP                 54.1 (7-253)
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