setting. The objective of this study was to evaluate the inci-dence of HO in a large nonmilitary amputee population anddescribe its characteristics.Design: Retrospective chart analysis.Setting: Amputee clinic at a large university-based tertiarycare medical center.Participants: Adult lower extremity amputees.Interventions: Non applicable.Main Outcome Measures: Presence of HO, demo-graphic characteristics.Results: In this cohort, 261 subjects were evaluated withaverage age at amputation of 50 years, and 69.3% men. Withregard to etiology, 45.6% were traumatic, 29.9% were vas-cular and 23.0% were from infection. Most patients hadtranstibial amputation (67%) while 29.5% had transfemoralamputation. Residual limb pain was noted in 44.1% of thesubjects while 55.9% reported phantom pain. Commonmedical comorbidities included hypertension (53.6%), dia-betes mellitus (37.5%) and coronary heart disease (25.7%).Using plain radiographs of the residual limb, 37 (14.2%) hadHO diagnosed. In the HO group, 8 (21.6%) had a vascularetiology, 23 (62.2%) were traumatic and 6 (16.2%) had aninfectious etiology. Logistic regression was performed usingHO as the dependent variable. The only variable significantlyassociated with HO diagnosis was the presence of diabetesmellitus.Conclusions: This is the largest study to date to character-ize the incidence of HO in a civilian amputee population. Wereport the incidence of HO as 14.2% but this condition isnot exclusive to individuals with traumatic amputation. Dia-betes mellitus was the only independent variable associatedwith HO.

Poster 123Informing the Consent Process: AdverseEffects of Fluoroscopically Guided LumbarZygapophyseal Joint Injections.Donald Macron, MD, MA (Hospital of the Universityof Pennsylvania, Philadelphia, PA); Gary P. Chimes,MD, PhD; Cynthia Garvan, PhD; Chris Plastaras, MD;Joshua D. Rittenberg, MD; Wesley L. Smeal, MD.

Disclosures: D. Macron, None.Objective: To inform the consent process by determiningthe type, incidence and causes of complications, and changesin pain scores after fluoroscopically guided, lumbar intra-articular zygapophyseal joint injections.Design: A retrospective cohort design.Setting: A single, tertiary, academic, outpatient physicalmedicine and rehabilitation interventional spine and muscu-loskeletal center.Participants: English-speaking adults aged 18-90 yearswho underwent fluoroscopically guided, lumbar zygapophy-seal joint injection(s) between March 2004 and April 2007.Interventions: Not applicable

Main Outcome Measures: After zygapophyseal injec-tion, adverse event data were recorded at discharge and byfollow-up telephone call on the next business day postproce-dure. In addition to the frequency of immediate or delayedcomplications, patient sex, pre- and post-procedure 11-pointLikert pain scale fluoroscopy time, and the presence of atrainee were also recordedResults: 194 patients (114 women) underwent 242 fluoro-scopically guided lumbar zygapophyseal joint injections. Themean (SD) patient age was 56.2 years (16.6). Trainees wereinvolved in 52.7% (127) of the procedures. 10 injections(4.1%) demonstrated immediate periprocedural events (9vagal-type events and 1 instance of steroid clogging theneedle). Follow-up data at next business day were availablefor 185 procedures, with 32 (17.3%) associated with adverseeffects. At next business day, the most common adverseeffects were injection site soreness (6.0%) and swelling(1.6%), increased pain (4.3%), and transient headache(1.6%). Patient gender, age, and trainee involvement in theprocedure were not found to have a significant effect onimmediate or delayed adverse effects.Conclusions: Lumbar zygapophyseal joint injections ap-pear safe, with adverse effects infrequent and predominantlyminor. The results should be incorporated into the informedconsent process for this procedure.

Poster 124Informing the Consent Process: AdverseEffects of Fluoroscopically Guided SacroiliacJoint Injections.Anand Joshi, MD, MHA (Hospital of the University ofPennsylvania, Philadelphia, PA); Gary P. Chimes,MD, PhD; Colleen M. Fitzgerald, MD; CynthiaGarvan, PhD; Chris Plastaras, MD; Joshua D.Rittenberg, MD; Wesley L. Smeal, MD.

Disclosures: A. Joshi, None.Objective: To inform the consent process by determiningthe type, incidence and causes of complications, and changesin pain scores after fluoroscopically guided, intra-articularsacroiliac joint injections.Design: A retrospective cohort study.Setting: A single, tertiary, academic, outpatient physicalmedicine and rehabilitation, interventional spine and mus-culoskeletal medicine center.Participants: English-speaking adults aged 18-90 yearswho underwent fluoroscopically guided, intra-articular sac-roiliac joint injection(s) between March 2004 and April2007.Interventions: Not applicable.Main Outcome Measures: After sacroiliac joint injec-tion, adverse event data were recorded at discharge and byfollow-up telephone call on the next business day postproce-dure. In addition to the frequency and type of immediate ordelayed complications, patient sex, pre- and post-procedure

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11-point Likert pain scale, fluoroscopy time, and the pres-ence of a trainee were also recorded.Results: 165 patients (136 women) underwent 195 proce-dures. The mean (SD) patient age was 47 (16) years. Traineeswere involved in 57% of procedures. The immediate compli-cations (frequency/percentage) reported were vasovagal re-action (4/195 or 2.1%) and steroid clogged needle (1/195 or0.5%). Follow-up data at next business day were available for132 procedures (68%). There were 33 adverse effects re-ported at follow-up, of which the most frequent were injec-tion site soreness (17/132 or 12.9%), pain exacerbation(7/132 or 5.3%) and facial flushing/sweating (3/132 or2.3%). There was no evidence of increased immediate ordelayed complications related to sex, trainee presence, orfluoroscopy time. However, the occurrence of delayed com-plications increased with younger age (P�.0029).Conclusions: Fluoroscopically guided intra-articular sac-roiliac joint injection is generally safe. The results shouldbe incorporated into the informed consent process for thisprocedure.

Poster 125Kim and Joo Index: The Ratio of Cross-Sectional Area of the Median Nerve toCross-Sectional Area of Carpal Tunnel inKorean Healthy Volunteers.HyoungSeop Kim (National Health Insurance IlsanHospital, Goyang, Republic of Korea); HyungKeunCho; Zee-A Han; SeungHo Joo; YongWook Kim;WonYoung Lee; Jinyoung Park; JungBin Shin.

Disclosures: H. Kim, None.Objective: To define the relationship between body indexesof normal Korean adults and cross-sectional areas (CSA) of thecarpal tunnel and median nerve using ultrasonography.Design: Analysis of data obtained from the carpal tunnel innormal Korean adults using ultrasonography.Setting: Outpatient rehabilitation center at a government-owned hospital.Participants: 30 healthy Korean men and 30 healthy Ko-rean women.Interventions: Not applicable.Main Outcome Measures: The CSA of the proximaland distal median nerve and carpal tunnel were obtainedusing ultrasonography. The proximal or distal Kim-Joo indexwas obtained by calculating the ratio between the proximal ordistal CSA of the median nerve to that of the carpal tunneland multiplying the value by 1000.Results: Statistically significant relationships were observedbetween body indexes and sonographic findings such asproximal and distal CSA of median nerve and carpal tunnel.However, the proximal and distal K-J indexes were notsignificantly related to body indexes or sex. Proximal CSAs ofmedian nerve and carpal tunnel were wider than distal values

but the value of distal K-J index was higher than that ofproximal K-J Index.Conclusions: The CSA of the median nerve is influencedby sex and body indexes. Therefore, we propose a newultrasonographic parameter, the Kim-Joo index, that is unaf-fected by body indexes and sex, to diagnose carpal tunnelsyndrome.

Poster 126Knee Effusion: Detectable Threshold byUltrasonography.Bo Young Hong (College of Medicine, The Cath-olic University of Korea, Seoul, Republic of Korea);Ye Rim Cho; Hye Won Kim; Young Jin Ko; Jong InLee; Seong Hoon Lim.

Disclosures: B. Hong, None.Objective: To identify the detectable threshold of kneeeffusion by ultrasonography (US) while infusing normal sa-line in osteoarthritis (OA) patients.Design: Prospective study.Setting: Rehabilitation department in a university hospital.Participants: Patients (N�40) with knee OA.Interventions: Intra-articular injection of 20 mL of normalsaline was done by milliliter under US guidance with thetransducer fixated at the midline longitudinal scan in themidline group and lateral longitudinal scan in the lateralgroup.Main Outcome Measures: After infusion of each mil-liliter, sonographic images were obtained. When 20 mL hadbeen injected, images with both scans were taken. For agreed13 patients, follow-up images were taken after 30 minutes ofexercise. Maximal depth of effusion was measured in eachimage by one of the authors.Results: The smallest amount of infusion for sonographicdetection of any effusion was 4.37 mL in the midline groupand 4.13 mL in the lateral group. Effusion of more than 2 mmdepth with US was seen after 7.84 mL and 7.36 mL ofinfusion in the midline and the lateral groups. And for 4 mmdepth, 11.58 mL and 13.13 mL of infusion were needed inthe midline and the lateral groups. After 30 minutes ofexercise, the depth of effusion was significantly decreased inboth scans, from 0.76 cm to 0.23 cm in the midline scans andfrom 0.92 cm to 0.48 cm in the lateral scans.Conclusions: To detect the knee effusion by US, about 4 mLof saline is needed. And for the definition of knee effusion withUS, we think 2 mm is more appropriate because 4-mm depthseems too much, which can lead to false-negative results.

Poster 127Large Lumbar Disk Herniations: A ClinicalOutcome Study of Nonsurgical Treatment.Ronald D. Karnaugh, MD (Hospital For SpecialSurgery, New York, NY); David Hoffman; ChristopherLutz; Gregory E. Lutz, MD; Stefan C. Muzin, MD.

S60 PRESENTATIONS