Posterior Glenoid Wear in Total Shoulder Arthroplasty: Eccentric Anterior Reaming Is Superior to Posterior Augment

Background

Uncorrected glenoid retroversion during total shoulder arthroplasty may lead to an increased likelihood of glenoid prosthetic loosening. Augmented glenoid components seek to correct retroversion to address posterior glenoid bone loss, but few biomechanical studies have evaluated their performance.

Questions/purposes

We compared the use of augmented glenoid components with eccentric reaming with standard glenoid components in a posterior glenoid wear model. The primary outcome for biomechanical stability in this model was assessed by (1) implant edge displacement in superior and inferior edge loading at intervals up to 100,000 cycles, with secondary outcomes including (2) implant edge load during superior and inferior translation at intervals up to 100,000 cycles, and (3) incidence of glenoid fracture during implant preparation and after cyclic loading.

Methods

A 12°-posterior glenoid defect was created in 12 composite scapulae, and the specimens were divided in two equal groups. In the posterior augment group, glenoid version was corrected to 8° and an 8°-augmented polyethylene glenoid component was placed. In the eccentric reaming group, anterior glenoid reaming was performed to neutral version and a standard polyethylene glenoid component was placed. Specimens were cyclically loaded in the superoinferior direction to 100,000 cycles. Superior and inferior glenoid edge displacements were recorded.

Results

Surviving specimens in the posterior augment group showed greater displacement than the eccentric reaming group of superior (1.01 ± 0.02 [95% CI, 0.89–1.13] versus 0.83 ± 0.10 [95% CI, 0.72–0.94 mm]; mean difference, 0.18 mm; p = 0.025) and inferior markers (1.36 ± 0.05 [95% CI, 1.24–1.48] versus 1.20 ± 0.09 [95% CI, 1.09–1.32 mm]; mean difference, 0.16 mm; p = 0.038) during superior edge loading and greater displacement of the superior marker during inferior edge loading (1.44 ± 0.06 [95% CI, 1.28–1.59] versus 1.16 ± 0.11 [95% CI, 1.02–1.30 mm]; mean difference, 0.28 mm; p = 0.009) at 100,000 cycles. No difference was seen with the inferior marker during inferior edge loading (0.93 ± 0.15 [95% CI, 0.56–1.29] versus 0.78 ± 0.06 [95% CI, 0.70–0.85 mm]; mean difference, 0.15 mm; p = 0.079). No differences in implant edge load were seen during superior and inferior loading. There were no instances of glenoid vault fracture in either group during implant preparation; however, a greater number of specimens in the eccentric reaming group were able to achieve the final 100,000 time without catastrophic fracture than those in the posterior augment group.

Conclusions

When addressing posterior glenoid wear in surrogate scapula models, use of angle-backed augmented glenoid components results in accelerated implant loosening compared with neutral-version glenoid after eccentric reaming, as shown by increased implant edge displacement at analogous times.

Clinical Relevance

Angle-backed components may introduce shear stress and potentially compromise stability. Additional in vitro and comparative long-term clinical followup studies are needed to further evaluate this component design.     

Biomechanical Outcomes of Bridge-enhanced Anterior Cruciate Ligament Repair Are Influenced by Sex in a Preclinical Model

Background

Despite the well-established role of sex on the anterior cruciate ligament (ACL) injury risk, its effects on ACL surgical outcomes remain controversial. This is particularly critical when developing novel surgical techniques to treat the injury because there are limited data existing on how these procedures will respond in each sex. One such approach is bridge-enhanced ACL repair, in which primary suture repair of the ACL is augmented with a bioactive scaffold saturated with autologous blood. It has shown comparable biomechanical outcomes to ACL reconstruction in preclinical models.

Questions/purposes

We asked (1) whether sex affects the biomechanical outcomes of bridge-enhanced ACL repair; and (2) if suture type (absorbable or nonabsorbable), used to repair the torn ACL, can minimize the potential sex discrepancies in outcomes after 15 weeks of healing in a large animal preclinical model.

Methods

Seventeen (eight males, nine females) Yorkshire pigs (Parson’s Farms, Hadley, MA, USA) underwent bilateral ACL transection and received bridge-enhanced ACL repair with an absorbable suture (n = 17) on one side and with a nonabsorbable suture (n = 17) on the other side. The leg receiving the absorbable suture was randomized within each animal. ACL structural properties and AP knee laxity for each knee were measured after 15 weeks of healing. Mixed linear models were used to compare the biomechanical outcomes between sexes and suture groups.

Results

When treated with absorbable suture, females had a lower ACL linear stiffness (females, 11 N/mm [range, 8–42]; males, 31 N/mm [range, 12–56]; difference, 20 N/mm [95% confidence interval {CI}, 4–36]; p = 0.032), ACL yield (females, 121 N [range, 56–316]; males, 224 N [range, 55–538]; difference, 103 N [95% CI, 6–200]; p = 0.078), and maximum load (females, 128 N [range, 63–332]; males, 241 N [range, 82–538]; difference, 114 N [95% CI, 15–212]; p = 0.052) than males after 15 weeks of healing. Female knees treated with absorbable suture had a lower linear stiffness (absorbable, 11 N/mm [range, 8–42]; nonabsorbable, 25 N/mm [range, 8–64]; difference, 14 [95% CI, 2–26] N; p = 0.054), ACL yield (absorbable, 121 N [range, 56–316]; nonabsorbable, 230 N [range, 149–573]; difference, 109 N [95% CI, 56–162]; p = 0.002), and maximum load (absorbable, 128 N [range, 63–332]; nonabsorbable, 235 N [range, 151–593]; difference, 107 N [95% CI, 51–163]; p = 0.002) along with greater AP knee laxity at 30° (absorbable, 9 mm [range, 5–12]; nonabsorbable, 7 mm [range, 2–13]; difference, 2 mm [95% CI, 1–4]; p = 0.034) than females treated with nonabsorbable suture. When repaired using nonabsorbable suture, the biomechanical outcomes were similar between female and male knees (p > 0.10).

Conclusions

Females had significantly worse biomechanical outcomes than males when the repairs were performed using absorbable sutures. However, the use of nonabsorbable sutures ameliorated these differences between males and females.

Clinical Relevance

The current findings highlight the critical role of sex on the biomechanical outcomes of bridge-enhanced ACL repair in a relevant large animal model. Better understanding of the mechanisms responsible for these observations using preclinical models and concomitant clinical studies in human patients may allow for additional development of sex-specific surgical and rehabilitative strategies with potentially improved outcomes in women.     

Elbow Positioning and Joint Insufflation Substantially Influence Median and Radial Nerve Locations

Background

The median and radial nerves are at risk of iatrogenic injury when performing arthroscopic arthrolysis with anterior capsulectomy. Although prior anatomic studies have identified the position of these nerves, little is known about how elbow positioning and joint insufflation might influence nerve locations.

Questions/purposes

In a cadaver model, we sought to determine whether (1) the locations of the median and radial nerves change with variation of elbow positioning; and whether (2) flexion and joint insufflation increase the distance of the median and radial nerves to osseous landmarks after correcting for differences in size of the cadaveric specimens.

Methods

The median and radial nerves were marked with a radiopaque thread in 11 fresh-frozen elbow specimens. Three-dimensional radiographic scans were performed in extension, in 90° flexion, and after joint insufflations in neutral rotation, pronation, and supination. Trochlear and capitellar widths were analyzed. The distances of the median nerve to the medial and anterior edge of the trochlea and to the coronoid were measured. The distances of the radial nerve to the lateral and anterior edge of the capitulum and to the anterior edge of the radial head were measured. We analyzed the mediolateral nerve locations as a percentage function of the trochlear and capitellar widths to control for differences regarding the size of the specimens.

Results

The mean distance of the radial nerve to the lateral edge of the capitulum as a percentage function of the capitellar width increased from 68% ± 17% in extension to 91% ± 23% in flexion (mean difference = 23%; 95% confidence interval [CI], 5%–41%; p = 0.01). With the numbers available, no such difference was observed regarding the location of the median nerve in relation to the medial border of the trochlea (mean difference = 5%; 95% CI, −13% to 22%; p = 0.309). Flexion and joint insufflation increased the distance of the nerves to osseous landmarks. The mean distance of the median nerve to the coronoid tip was 5.4 ± 1.3 mm in extension, 9.1 ± 2.3 mm in flexion (mean difference = 3.7 mm; 95% CI, 2.04–5.36 mm; p < 0.001), and 12.6 ± 3.6 mm in flexion and insufflation (mean difference = 3.5 mm; 95% CI, 0.81–6.19 mm; p = 0.008). The mean distance of the radial nerve to the anterior edge of the radial head increased from 4.7 ± 1.8 mm in extension to 7.7 ± 2.7 mm in flexion (mean difference = 3.0 mm; 95% CI, 0.96–5.04 mm; p = 0.005) and to 11.9 ± 3.0 mm in flexion with additional joint insufflation (mean difference = 4.2 mm; 95% CI, 1.66–6.74 mm; p = 0.002).

Conclusions

The radial nerve shifts medially during flexion from the lateral to the medial border of the inner third of the capitulum. The median nerve is located at the medial quarter of the joint. The distance of the median and radial nerves to osseous landmarks doubles from extension to 90° flexion and triples after joint insufflation.

Clinical Relevance

Elbow arthroscopy with anterior capsulectomy should be performed cautiously at the medial aspect of the joint to avoid median nerve lesions. Performing arthroscopic anterior capsulectomy in flexion at the lateral aspect of the joint and in slight extension at the medial edge of the capitulum could enhance safety of this procedure.     

Morbid Obesity: Increased Risk of Failure After Aseptic Revision TKA

Background

Patients with obesity are known to have a higher risk of complications after primary TKA; however, there is a paucity of data regarding the effects of obesity with revision TKAs.

Questions/purposes

We asked the following questions : (1) Are patients with morbid obesity (BMI ≥ 40 kg/m²) at greater risk for repeat revision, reoperation, or periprosthetic joint infection (PJI) compared with patients without obesity (BMI < 30 kg/m²) after an index revision TKA performed for aseptic reasons? (2) Do patients who are not obese achieve higher Knee Society pain and function scores after revision TKA for aseptic reasons?

Methods

We used a retrospective cohort study with 1:1 matching for sex, age (± 3 years) and date of surgery (± 1 year) to compare patients with morbid obesity with patients without obesity with respect to repeat revision, reoperation, and PJI. Using our institution’s total joint registry, we identified 1291 index both-component (femoral and tibial) aseptic revision TKAs performed during a 15-year period (1992–2007). Of these, 120 revisions were in patients with morbid obesity (BMI ≥ 40 kg/m²) and 624 were in patients with a BMI less than 30 kg/m². We then considered only patients with a minimum 5-year followup, which was available for 77% of patients with morbid obesity and 76% of patients with a BMI less than 30 kg/m² (p = 0.84). All patients with morbid obesity who met criteria were included (morbid obesity group: n = 93; average followup, 7.9 years) and compared with a matched cohort of patients with a BMI less than 30 kg/m² (nonmorbid obesity group: n = 93; average followup, 7.3 years). Medical records were reviewed to gather details regarding complications and clinical outcomes.

Results

Overall, patients with morbid obesity had an increased risk of repeat revision (hazard ratio [HR], 3.8; 95% CI, 1.2–16.5; p < 0.02), reoperation (HR, 2.9; 95% CI, 1.3–7.4; p < 0.02), and PJI (HR, 6.4; 95% CI, 1.2–119.7; p < 0.03). Implant survival rates were 96% (95% CI, 92%–100%) and 100% at 5 years, and 81% (95% CI, 70%–92%) and 93% (95% CI, 86%–100%) at 10 years for the patients with morbid obesity and those without morbid obesity, respectively (p = 0.02). At 10 years, The Knee Society pain (90 [95% CI, 88–92] vs 76 [95% CI, 71–81]; p < 0.01) and function (61 [95% CI, 53–69] vs 57 [95% CI, 42–52]; p < 0.01) scores were higher in patients with a BMI less than 30 kg/m² compared with patients with morbid obesity.

Conclusion

Morbid obesity is associated with increased rates of rerevision, reoperation, and PJI after aseptic revision TKA. As the time-sensitive nature of revision surgery may not always allow for patient or comorbidity optimization, these results emphasize the need for improving our care of patients with morbid obesity earlier on during the osteoarthritic process. Additional studies are needed to risk stratify patients in the morbidly obese population to better guide patient selection and effective optimization.

Level of Evidence

Level III, therapeutic study.     

Low-intensity Pulsed Ultrasound Enhances Bone Repair in a Rabbit Model of Steroid-associated Osteonecrosis

Background

Steroids are a leading cause of femoral head osteonecrosis. Currently there are no medications available to prevent and/or treat steroid-associated osteonecrosis. Low-intensity pulsed ultrasound (LIPUS) was approved by the FDA for treating delayed union of bone fractures. Some studies have reported that LIPUS can enhance bone formation and local blood flow in an animal model of fracture healing. However, whether the effect of osteogenesis and neovascularization by LIPUS can enhance the repair progress in steroid-associated osteonecrosis is unknown.

Questions/purposes

We hypothesized that LIPUS may facilitate osteogenesis and neovascularization in the reparative processes of steroid-associated osteonecrosis. Using a rabbit animal model, we asked whether LIPUS affects (1) bone strength and trabecular architecture; (2) blood vessel number and diameter; and (3) BMP-2 and VEGF expression.

Methods

Bilateral femoral head necrosis was induced by lipopolysaccharide and methylprednisolone in 24 rabbits. The left femoral heads of rabbits received LIPUS therapy (200 mW/cm²) for 20 minutes daily and were classified as the LIPUS group. The right femoral heads of the same rabbits did not receive therapy and were classified as the control group. All rabbits were euthanized 12 weeks after LIPUS therapy. Micro-CT, biomechanical testing, histologic evaluation, immunohistochemistry, quantitative real-time PCR, and Western blot were used for examination of the effects of LIPUS.

Results

Twelve weeks after LIPUS treatment, the loading strength in the control group was 355 ± 38 N (95% CI, 315–394 N), which was lower (p = 0.028) than that in the LIPUS group (441 ± 78 N; 95% CI, 359–524 N). The bone tissue volume density (bone volume/total volume) in the LIPUS group (49.29% ± 12.37%; 95 % CI, 36.31%–62.27%) was higher (p = 0.022) than that in the control group (37.93% ± 8.37%; 95 % CI, 29.15%–46.72%). The percentage of empty osteocyte lacunae in the LIPUS group (17% ± 4%; 95% CI, 15%–20%) was lower (p = 0.002) than that in the control group (26% ± 9%; 95% CI, 21%–32%). The mineral apposition rate (μm/day) in the LIPUS group (2.3 ± 0.8 μm/day; 95% CI, 1.8 2.8 μm/day) was higher (p = 0.001) than that in the control group (1.6 ± 0.3 μm/day; 95% CL, 1.4–1.8 μm/day). The number of blood vessels in the LIPUS group (7.8 ± 3.6/mm²; 95% CI, 5.5–10.1 mm²) was greater (p = 0.025) than the number in the control group (5.7 ± 2.6/mm²; 95% CI, 4.0–7.3 mm²). Messenger RNA (mRNA) and protein expression of BMP-2 in the LIPUS group (75 ± 7, 95% CI, 70–79; and 30 ± 3, 95% CI, 28–31) were higher (both p < 0.001) than those in the control groups (46 ± 5, 95% CI, 43–49; and 15 ± 2, 95% CI, 14–16). However, there were no differences (p = 0.114 and 0.124) in mRNA and protein expression of vascular endothelial growth factor between the control (26 ± 3, 95% CI, 24–28; and 22 ± 6, 95% CI, 18–26) and LIPUS groups (28 ± 2, 95% CI, 26–29; and 23 ± 6, 95% CI, 19–27).

Conclusions

The results of this study indicate that LIPUS promotes osteogenesis and neovascularization, thus promoting bone repair in this steroid-associated osteonecrosis model.

Clinical Relevance

LIPUS may be a promising modality for the treatment of early-stage steroid-associated osteonecrosis. Further research, including clinical trials to determine whether LIPUS has a therapeutic effect on patients with early-onset steroid-associated osteonecrosis may be warranted.     

What is the Best Clinical Test for Assessment of the Teres Minor in Massive Rotator Cuff Tears?

Background

Few studies define the clinical signs to evaluate the integrity of teres minor in patients with massive rotator cuff tears. CT and MRI, with or without an arthrogram, can be limited by image quality, soft tissue density, motion artifact, and interobserver reliability. Additionally, the ill-defined junction between the infraspinatus and teres minor and the larger muscle-to-tendon ratio of the teres minor can contribute to error. Therefore, we wished to determine the validity of clinical testing for teres minor tears.

Question/Purposes

The aim of this study was to determine the accuracy of commonly used clinical signs (external rotation lag sign, drop sign, and the Patte test) for diagnosing the teres minor’s integrity.

Methods

We performed a prospective evaluation of patients referred to our shoulder clinic for massive rotator cuff tears determined by CT arthrograms. The posterosuperior rotator cuff was examined clinically and correlated with CT arthrograms. We assessed interobserver reliability for CT assessment and used three different clinical tests of teres minor function (the external rotation lag sign, drop sign, and the Patte test). One hundred patients with a mean age of 68 years were available for the analysis.

Results

The most accurate test for teres minor dysfunction was an external rotation lag sign greater than 40°, which had a sensitivity of 100% (95% CI, 80%–100%) and a specificity of 92% (95% CI, 84%–96%). External rotation lag signs greater than 10° had a sensitivity of 100% (95% CI, 80%–100%) and a specificity of 51% (95% CI, 40%–61%). The Patte sign had a sensitivity of 93% (95% CI, 70%–99%) and a specificity of 72% (95% CI, 61%–80%). The drop sign had a sensitivity of 87% (95% CI, 62%–96%) and a specificity of 88% (95% CI, 80%–93%). An external rotation lag sign greater than 40° was more specific than an external rotation lag sign greater than 10° (p < 0.001), and a Patte sign (p < 0.001), but was not more specific than the drop sign (p < 0.47). There was poor correlation between involvement of the teres minor and loss of active external rotation.

Conclusions

Clinical signs can predict anatomic patterns of teres minor dysfunction with good accuracy in patients with massive rotator cuff tears. This study showed that the most accurate test for teres minor dysfunction is an external rotation lag sign and that most patients’ posterior rotator cuff tears do not lose active external rotation. Because imaging is not always accurate, examination for integrity of the teres minor is important because it may be one of the most important variables affecting the outcome of reverse shoulder arthroplasty for massive rotator cuff tears, and the functional effects of tears in this muscle on day to day activities can be significant. Additionally, teres minor integrity affects the outcomes of tendon transfers, therefore knowledge of its condition is important in planning repairs.

Level of Evidence

Level III, diagnostic study.     

Disability After Deployment Injury: Are Women and Men Service Members Different?

Background

Civilian trauma literature suggests sexual dimorphism in outcomes after trauma. Because women represent an increasing demographic among veterans, the question remains if war trauma outcomes, like civilian trauma outcomes, differ between genders.

Questions/purposes

(1) Do women service members develop different conditions resulting in long-term disability compared with men service members after injuries sustained during deployment? (2) Do women service members have more or less severe disability after deployment injury compared with men service members? (3) Are men or women more likely to return to duty after combat injury?

Methods

The Department of Defense Trauma Registry was queried for women injured during deployment from 2001 to 2011. The subjects were then queried in the Physical Evaluation Board database to determine each subject’s return-to-duty status and what disabling conditions and disability percentages were assigned to those who did not return to duty. Frequency of disabling conditions, disability percentages, and return-to-duty rates for 368 women were compared with a previously published cohort of 450 men service members, 378 of whom had orthopaedic injuries.

Results

Women who were unable to return to duty had a higher frequency of arthritic conditions (58% [48 of 83] of women versus 35% [133 of 378] of men, p = 0.002; relative risk [RR], 1.64; 95% confidence interval [CI], 1.307–2.067) and lower frequencies of general chronic pain (1% [one of 83] of women versus 19% [59 of 378] of men, p < 0.001; RR, 0.08; 95% CI, 0.011–0.549) and neurogenic pain disorders (1% [one of 83] of women versus 7% [27 of 378] of men, p = 0.0410; RR, 0.169; 95% CI, 0.023–1.224). Women had more severely rated posttraumatic stress disorder (PTSD) compared with men (38% ± 23% versus 19% ± 17%). Forty-eight percent (64 of 133) of battle-injured women were unable to return to active duty, resulting in a lower return-to-duty rate compared with men (34% [450 of 1333]; p = 0.003).

Conclusions

After deployment-related injury, women have higher rates of arthritis, lower rates of pain disorders, and more severely rated PTSD compared with men. Women are unable to return to duty more often than men injured in combat. These results suggest some difference between men’s and women’s outcomes after deployment injury, important information for military and Veterans Administration providers seeking to minimize postdeployment disability.

Level of Evidence

Level III, prognostic study.     

Do Patients With a Failed Metal-on-metal Hip Implant With a Pseudotumor Present Differences in Their Peripheral Blood Lymphocyte Subpopulations?

Background

Early adverse tissue reactions around metal-on-metal (MoM) hip replacements, especially pseudotumors, are a major concern. Because the causes and pathomechanisms of these pseudotumors remain largely unknown, clinical monitoring of patients with MoM bearings is challenging.

Questions/purposes

The purpose of this study was to compare the lymphocyte subpopulations in peripheral blood from patients with a failed MoM hip implant with and without a pseudotumor and patients with a well-functioning MoM hip implant without a pseudotumor. Potential differences in the systemic immune response are expected to reflect local differences in the periprosthetic tissues.

Methods

Consenting patients who underwent a revision of a failed MoM hip implant at The Ottawa Hospital (TOH) from 2011 to 2014, or presented with a well-functioning MoM hip implant for a postoperative clinical followup at TOH from 2012 to 2013, were recruited for this study, unless they met any of the exclusion criteria (including diagnosed conditions that can affect peripheral blood lymphocyte subpopulations). Patients with a failed implant were divided into two groups: those with a pseudotumor (two hip resurfacings and five total hip arthroplasties [THAs]) and those without a pseudotumor (10 hip resurfacings and two THAs). Patients with a well-functioning MoM hip implant (nine resurfacings and three THAs) at 5 or more years postimplantation and who did not have a pseudotumor as demonstrated sonographically served as the control group. Peripheral blood subpopulations of T cells (specifically T helper [Th] and cytotoxic T [Tc]), B cells, natural killer (NK) cells, memory T and B cells as well as type 1 (expressing interferon-γ) and type 2 (expressing interleukin-4) Th and Tc cells were analyzed by flow cytometry after immunostaining. Serum concentrations of cobalt and chromium were measured by inductively coupled plasma-mass spectrometry.

Results

The mean percentages of total memory T cells and, specifically, memory Th and memory Tc cells were lower in patients with a failed MoM hip implant with a pseudotumor than in both patients with a failed implant without a pseudotumor and patients with a well-functioning implant without a pseudotumor (memory Th cells: 29% ± 5% [means ± SD] versus 55% ± 17%, d = 1.8, 95% confidence interval [CI] [1.2, 2.5] and versus 48% ± 14%, d = 1.6, 95% CI [1.0, 2.2], respectively; memory Tc cells: 18% ± 5% versus 45% ± 14%, d = 2.3, 95% CI [1.5, 3.1] and versus 41% ± 12%, d = 2.3, 95% CI [1.5, 3.1], respectively; p < 0.001 in all cases). The mean percentage of memory B cells was also lower in patients with a failed MoM hip implant with a pseudotumor than in patients with a well-functioning implant without a pseudotumor (12% ± 8% versus 29% ± 16%, d = 1.3, 95% CI [0.7, 1.8], p = 0.025). In addition, patients with a failed MoM hip implant with a pseudotumor had overall lower percentages of type 1 Th cells than both patients with a failed implant without a pseudotumor and patients with a well-functioning implant without a pseudotumor (5.5% [4.9%–5.8%] [median with interquartile range] versus 8.7% [6.5%–10.2%], d = 1.4, 95% CI [0.8, 2.0] and versus 9.6% [6.4%–11.1%], d = 1.6, 95% CI [1.0, 2.2], respectively; p ≤ 0.010 in both cases). Finally, serum cobalt concentrations in patients with a failed MoM hip implant with a pseudotumor were overall higher than those in patients with a well-functioning implant without a pseudotumor (5.8 µg/L [2.9–17.0 µg/L] versus 0.9 µg/L [0.6–1.3 µg/L], d = 2.2, 95% CI [1.4, 2.9], p < 0.001).

Conclusions

Overall, results suggest the presence of a type IV hypersensitivity reaction, with a predominance of type 1 Th cells, in patients with a failed MoM hip implant with a pseudotumor.

Clinical Relevance

The lower percentages of memory T cells (specifically Th and Tc) as well as type 1 Th cells in peripheral blood of patients with a failed MoM hip implant with a pseudotumor could potentially become diagnostic biomarkers for the detection of pseudotumors. Although implant design (hip resurfacing or THA) did not seem to affect the results, as suggested by the scatter of the data with respect to this parameter, future studies with additional patients could include the analysis of implant design in addition to correlations with histological analyses of specific Th subsets in periprosthetic tissues.     

Deltoid Tuberosity Index: A Simple Radiographic Tool to Assess Local Bone Quality in Proximal Humerus Fractures

Background

Osteoporosis may complicate surgical fixation and healing of proximal humerus fractures and should be assessed preoperatively. Peripheral quantitative CT (pQCT) and the Tingart measurement are helpful methods, but both have limitations in clinical use because of limited availability (pQCT) or fracture lines crossing the area of interest (Tingart measurement). The aim of our study was to introduce and validate a simple cortical index to assess the quality of bone in proximal humerus fractures using AP radiographs.

Questions/purposes

We asked: (1) How do the deltoid tuberosity index and Tingart measurement correlate with each other, with patient age, and local bone mineral density (BMD) of the humeral head, measured by pQCT? (2) Which threshold values for the deltoid tuberosity index and Tingart measurement optimally discriminate poor local bone quality of the proximal humerus? (3) Are the deltoid tuberosity index and Tingart measurement clinically applicable and reproducible in patients with proximal humerus fractures?

Methods

The deltoid tuberosity index was measured immediately above the upper end of the deltoid tuberosity. At this position, where the outer cortical borders become parallel, the deltoid tuberosity index equals the ratio between the outer cortical and inner endosteal diameter. In the first part of our study, we retrospectively measured the deltoid tuberosity index on 31 patients (16 women, 15 men; mean age, 65 years; range, 22–83 years) who were scheduled for elective surgery other than fracture repair. Inclusion criteria were available native pQCT scans, AP shoulder radiographs taken in internal rotation, and no previous shoulder surgery. The deltoid tuberosity index and the Tingart measurement were measured on the preoperative internal rotation AP radiograph. The second part of our study was performed by reviewing 40 radiographs of patients with proximal humerus fractures (31 women, nine men; median age, 65 years; range, 22–88 years). Interrater (two surgeons) and intrarater (two readings) reliabilities, applicability, and diagnostic accuracy were assessed.

Results

The correlations between radiograph measurements and local BMD (pQCT) were strong for the deltoid tuberosity index (r = 0.80; 95% CI, 0.63–0.90; p < 0.001) and moderate for the Tingart measurement (r = 0.67; 95% CI, 0.42–0.83; p < 0.001). There was moderate correlation between patient age and the deltoid tuberosity index (r = 0.65; p < 0.001), patient age and the Tingart measurement (r = 0.69; p < 0.001), and patient age and pQCT (r = 0.73; p < 0.001). The correlation between the deltoid tuberosity index and the Tingart measurement was strong (r = 0.84; p < 0.001). We determined the cutoff value for the deltoid tuberosity index to be 1.44, with the area under the curve = 0.87 (95% CI, 0.74–0.99). This provided a sensitivity of 0.88 and specificity of 0.80. For the Tingart measurement, we determined the cutoff value to be 5.3 mm, with the area under the curve = 0.83 (95% CI, 0.67–0.98), which resulted in a sensitivity of 0.81 and specificity of 0.85. The intraobserver reliability was high and not different between the Tingart measurement (intraclass correlation coefficients [ICC] = 0.75 and 0.88) and deltoid tuberosity index (ICC = 0.88 and 0.82). However, interobserver reliability was higher for the deltoid tuberosity index (ICC = 0.96; 95% CI, 0.93–0.98) than for the Tingart measurement (ICC = 0.85; 95% CI, 0.69–0.93).The clinical applicability on AP radiographs of fractures was better for the deltoid tuberosity index (p = 0.025) because it was measureable on more of the radiographs (77/80; 96%) than the Tingart measurement (69/80; 86%).

Conclusions

The deltoid tuberosity index correlated strongly with local BMD measured on pQCT and our study evidence shows that it is a reliable, simple, and applicable tool to assess local bone quality in the proximal humerus. We found that deltoid tuberosity index values consistently lower than 1.4 indicated low local BMD of the proximal humerus. Furthermore, the use of the deltoid tuberosity index has important advantages over the Tingart measurement regarding clinical applicability in patients with proximal humerus fractures, when fracture lines obscure the Tingart measurement landmarks. However, further studies are needed to assess the effect of the deltoid tuberosity index measurement and osteoporosis on treatment and outcome in patients with proximal humerus fractures.

Level of Evidence

Level IV, diagnostic study.     

Are There Sex Differences in Knee Cartilage Composition and Walking Mechanics in Healthy and Osteoarthritis Populations?

Background

Women are at a greater risk for knee osteoarthritis (OA), but reasons for this greater risk in women are not well understood. It may be possible that differences in cartilage composition and walking mechanics are related to greater OA risk in women.

Questions/purposes

(1) Do women have higher knee cartilage and meniscus T_1ρ than men in young healthy, middle-aged non-OA and OA populations? (2) Do women exhibit greater static and dynamic (during walking) knee loading than men in young healthy, middle-aged non-OA and OA populations?

Methods

Data were collected from three cohorts: (1) young active (< 35 years) (20 men, 13 women); (2) middle-aged (≥ 35 years) without OA (Kellgren-Lawrence [KL] grade < 2) (43 men, 65 women); and (3) middle-aged with OA (KL > 1) (18 men, 25 women). T_1ρ and T₂ relaxation times for cartilage in the medial knee, lateral knee, and patellofemoral compartments and medial and lateral menisci were quantified with 3.0-T MRI. A subset of the participants underwent three-dimensional motion capture during walking for calculation of peak knee flexion and adduction moments, flexion and adduction impulses, and peak adduction angle. Differences in MR, radiograph, and gait parameters between men and women were compared in the three groups separately using multivariate analysis of variance.

Results

Women had higher lateral articular cartilage T_1ρ (men = 40.5 [95% confidence interval {CI}, 38.8–42.3] ms; women = 43.3 [95% CI, 41.9–44.7] ms; p = 0.017) and patellofemoral T_1ρ (men = 44.4 [95% CI, 42.6–46.3] ms; women = 48.4 [95% CI, 46.9–50.0] ms; p = 0.002) in the OA group; and higher lateral meniscus T_1ρ in the young group (men = 15.3 [95% CI, 14.7–16.0] ms; women = 16.4 [95% CI, 15.6–17.2] ms; p = 0.045). The peak adduction moment in the second half of stance was lower in women in the middle-aged (men = 2.05 [95% CI, 1.76–2.34] %BW*Ht; women = 1.66 [95% CI, 1.44–1.89] %BW*Ht; p = 0.037) and OA (men = 2.34 [95% CI, 1.76–2.91] %BW*Ht; women = 1.42 [95% CI, 0.89–1.94] %BW*Ht; p = 0.022) groups. Static varus from radiographs was lower in women in the middle-aged (men = 178° [95% CI, 177°–179°]; women = 180° [95% CI, 179°–181°]; p = 0.002) and OA (men = 176° [95% CI, 175°–178°]; women = 180° [95% CI, 179°–181°]; p < 0.001) groups. Women had lower varus during walking in all three groups (young: men = 4° [95% CI, 3°–6°]; women = 2° [95% CI, 0°–3°]; p = 0.013; middle-aged: men = 2° [95% CI, 1°–3°]; women = 0° [95% CI, −1° to 1°]; p = 0.015; OA: men = 4° [95% CI, 2°–6°]; women = 0° [95% CI, −2° to 2°]; p = 0.011). Women had a higher knee flexion moment (men = 4.24 [95% CI, 3.58–4.91] %BW*Ht; women 5.40 [95% CI, 4.58–6.21] %BW*Ht; p = 0.032) in the young group.

Conclusions

These data demonstrate differences in cartilage composition and gait mechanics between men and women in young healthy, middle-aged healthy, and OA cohorts. Considering the cross-sectional nature of the study, longitudinal research is needed to investigate if these differences in cartilage composition and walking mechanics are associated with a greater risk of lateral tibiofemoral or patellofemoral OA in women. Future studies should also investigate the relative risk of lateral versus medial patellofemoral cartilage degeneration risk in women compared with men.

Level of Evidence

Level III, retrospective study.     

Latissimus Dorsi and Teres Major Transfer With Reverse Shoulder Arthroplasty Restores Active Motion and Reduces Pain for Posterosuperior Cuff Dysfunction

Background

In patients with rotator cuff dysfunction, reverse shoulder arthroplasty can restore active forward flexion, but it does not provide a solution for the lack of active external rotation because of infraspinatus and the teres minor dysfunction. A modified L’Episcopo procedure can be performed in the same setting wherein the latissimus dorsi and teres major tendons are transferred to the lateral aspect of proximal humerus in an attempt to restore active external rotation.

Questions/purposes

(1) Do latissimus dorsi and teres major tendon transfers with reverse shoulder arthroplasty improve external rotation function in patients with posterosuperior rotator cuff dysfunction? (2) Do patients experience less pain and have improved outcome scores after surgery? (3) What are the complications associated with reverse shoulder arthroplasty with latissimus dorsi and teres major transfer?

Methods

Between 2007 and 2010, we treated all patients undergoing shoulder arthroplasty who had a profound external rotation lag sign and advanced fatty degeneration of the posterosuperior rotator cuff (infraspinatus plus teres minor) with this approach. A total of 21 patients (mean age 66 years; range, 58–82 years) were treated this way and followed for a minimum of 2 years (range, 26–81 months); none was lost to followup, and all have been seen in the last 5 years. We compared pre- and postoperative ranges of motion, pain, and functional status; scores were drawn from chart review. We also categorized major and minor complications.

Results

Active forward flexion improved from 56° ± 36° to 120° ± 38° (mean difference: 64° [95% confidence interval {CI}, 45°–83°], p < 0.001). Active external rotation with the arm adducted improved from 6° ± 16° to 38° ± 14° (mean difference: 30° [95% CI, 21°–39°], p < 0.001); active external rotation with the arm abducted improved from 19° ± 25° to 74° ± 22° (mean difference: 44° [95% CI, 22°–65°], p < 0.001). Pain visual analog score improved from 8.4 ± 2.3 to 1.7 ± 2.1 (mean difference: −6.9 [95% CI, −8.7 to −5.2], p < 0.001), and Single Assessment Numeric Evaluation score improved from 28% ± 21% to 80% ± 24% (mean difference: 46% [95% CI, 28%–64%], p < 0.001). There were six major complications, five of which were treated operatively. Overall, three patients’ latissimus and teres major transfer failed based on persistent lack of external rotation.

Conclusions

In patients with posterior and superior cuff deficiency, reverse shoulder arthroplasty combined with latissimus dorsi and teres major transfer through a single deltopectoral incision can reliably increase active forward flexion and external rotation. Patients experience pain relief and functional improvement but have a high rate of complications; therefore, we recommend the procedure be limited to patients indicated for reverse who have profound external rotation loss and a high grade of infraspinatus/teres minor fatty atrophy.

Level of Evidence

Level IV, therapeutic study.     

Does Patient Sex Affect the Anatomic Relationships Between the Sternoclavicular Joint and Posterior Vascular Structures?

Background

Despite increased concern for injury during surgical reconstruction of the sternoclavicular joint, to our knowledge there are few studies detailing the vascular relationships adjacent to the joint.

Questions/purposes

We investigated sex differences in the following relationships for sternoclavicular joint reconstruction: (1) safe distance from the posterior surface of the medial clavicle’s medial and lateral segments to the major vessels, (2) length of the first costal cartilage and safe distance from the first rib to the internal mammary artery, (3) minimum distance medial to the sternoclavicular joint for optimal hole placement, and (4) safe distance from the manubrium to the great vessels.

Methods

Fifty normal postcontrast CT scans of the chest were reviewed. Means, standard deviations, and 95% CI were calculated for each aforementioned measurement. A t-test was used to determine if a sex difference exists (p ≤ 0.05).

Results

At the medial end of the clavicle, the safe distance from the medial segment (first 10 mm) to the major vessels was greater in males than in females (3.5 mm versus 2.4 mm, respectively; 95% CI, 3 mm–4 mm versus 1.7 mm–3 mm, respectively; p = 0.014). For the lateral segment (next 10 mm), the distance also was safer in males than in females (3.3 mm versus 1.7 mm, respectively; 95% CI, 2.7 mm–4 mm versus 1.1 mm–2.3 mm, respectively; p < 0.001). The mean length of the first costal cartilage also was greater in males (35.8 mm versus 30.1 mm, respectively; 95% CI, 33.8 mm–37.8 mm versus 28.5 mm–31.9 mm, respectively; p < 0.001); the distance from the first costochondral joint to the internal mammary artery was safer in males than in females (19.1 mm versus 15.4 mm, respectively; 95% CI, 16.5 mm–21.8 mm versus 13 mm–17.9 mm, respectively; p = 0.05). The minimum distance to avoid inadvertent penetration of the sternoclavicular joint was greater in males than in females (16 mm versus 12.3 mm, respectively; 95% CI, 14.6 mm–17.5 mm versus 11 mm–13.6 mm, respectively; p < 0.001). The distance to vessels after penetration of the manubrium was not different between males and females (5.6 mm versus 3.9, respectively; 95% CI, 4.4 mm–6.8 mm versus 2.6 mm–5.2 mm, respectively; p = 0.06).

Conclusions

This study makes apparent the intimate relationships between vessels and the musculoskeletal structures associated with sternoclavicular reconstruction. Based on our findings, we recommend considering the sex of the patient, using caution when drilling, and protecting essential structures posterior to the joint.     

How Are Dysplastic Hips Different? A Three-dimensional CT Study

Background

Surgical correction of acetabular dysplasia can postpone or prevent joint degeneration. The specific abnormalities that make up the dysplastic hip are controversial.

Questions/purposes

(1) What are the relative size, shape, and orientations of the typical nondysplastic hip? (2) How do these variables differ in the developmentally dysplastic hip? (3) Are there version differences between the acetabuli of dysplastic and nondysplastic hips? (4) Are there pairs of variables in which the change in one is always accompanied by a change in the other for both nondysplastic and dysplastic acetabuli?

Methods

Of 117 consecutive three-dimensional (3-D) CT scans performed for hip dysplasia between March 1988 and October 1995, 48 met criteria of developmentally dysplastic hips by plain radiography. These were retrospectively compared with 55 pelvic 3-D CT scans culled from 81 consecutive scans performed for reasons other than hip dysplasia (ie, hip pain, trauma, infection) that did not affect the hip or pelvic landmarks. The 3-D reconstructions were orientated anatomically for standardization of the measurements to be compared. Representative 3-D volumes of the acetabular space were constructed from which we could measure anatomic positions and dimensional information. One author performed all image orientation and measurements.

Results

Nondysplastic acetabuli are essentially hemispheric with height equal to width and twice the depth. The dysplastic acetabuli were elongated in females (52.4 ± 6.2 mm for dysplastic versus 46.5 ± 4.6 mm for nondysplastic (mean difference, 5.0; 95% confidence interval [CI], 1.9–8.0; p = 0.002) and shallower in both females (18.7 ± 4.9 mm for dysplastic versus 23.6 ± 4.0 mm for nondysplastic; mean difference, 6.5; 95% CI, 4.4–8.5; p < 0.0001) and males (21.1 ± 4.8 mm for dysplastic versus 25.0 ± 4.3 mm for nondysplastic, mean difference, 5.3; 95% CI, 2.6–8.1; p = 0.0002); width was similar to that of nondysplastic hips. Acetabular openings were slightly more vertical than nondysplastic hips in females (5°; 95% CI, 1.9–8.1; p = 0.002) but not in male subjects. The dysplastic acetabuli were smaller in volume (18% in females, p = 0.002, and 19% in males, p = 0.0012) and had less space occupied by the femoral head compared with nondysplastic hips (p < 0.0001 for females, p < 0.0001 for males). Dysplastic hip midacetabulum was 4° more anteverted in females (95% CI, 0.5–6.8; p = 0.022) but not for males (p = 0.538). The upper dysplastic acetabulum was more retroverted in females and males (10.2°; 95% CI, 5.5–15; p < 0.0001, and 7.0°; 95% CI, 0.6–13.4; p = 0.032, respectively). Acetabular volumes in nondysplastic and dysplastic hips were related to acetabular width but not to length.

Conclusions

Developmentally dysplastic acetabuli are not deficient in merely a single dimension but are globally deficient. The subluxated femoral head lies in the elongated and retroverted superior acetabulum, which becomes progressively shallower as the acetabulum increases in length. Focally deficient anterior or posterior femoral head coverage is uncommon. Current procedures that redirect the acetabulum, no matter how technically successful, cannot fully compensate for the incongruence of a spherical femoral head within a shallow and elongated acetabulum unless corrected at an early age when acetabular remodeling is possible. Early detection and treatment of acetabular dysplasia should be emphasized.

Level of Evidence

Level III, prognostic study.     

Acetate Templating on Digital Images Is More Accurate Than Computer-based Templating for Total Hip Arthroplasty

Background

Templating is an important aspect of preoperative planning for total hip arthroplasty and can help determine the size and positioning of the prosthesis. Historically, templating has been performed using acetate templates over printed radiographs. As a result of the increasing use of digital imaging, surgeons now either obtain additional printed radiographs solely for templating purposes or use specialized digital templating software, both of which carry additional cost.

Questions/purposes

The purposes of this study was to compare acetate templating of digitally calibrated images on an LCD monitor to digital templating in terms of (1) accuracy; (2) reproducibility; and (3) time efficiency.

Methods

Acetate onlay templating was performed directly over digital radiographs on an LCD monitor and was compared with digital templating. Five separate observers participated in this study templating on 52 total hip arthroplasties. For the acetate templating, the digital images were magnified to the scaled reference on the templates provided by the manufacturer (ratio 1.2:1) before templating using a 25-mm marker as a reference. Both the acetate and digital templating results were then compared with the actual implanted components to determine accuracy. Interobserver and intraobserver variability was determined by an intraclass correlation coefficient. Observers recorded time to complete templating from the time of complete upload of patients’ imaging onto the system to completion of templating.

Results

Both acetate and digital templates demonstrated moderate accuracy in predicting within one size of the eventual implanted acetabular cup (77% [199 of 260]; 70% [181 of 260], respectively; p = 0.050; 95% confidence interval [CI], 0.058–0.32), whereas acetate templating was better at predicting the femoral stem compared to digital templating (75% [195 of 260]; 60% [155 of 260], respectively; p < 0.001; 95% CI, 0.084–0.32). Acetate templating showed moderate to substantial interobserver agreement (cup intraclass correlation coefficient [ICC] = 0.55; 95% CI, 0.14–0.86; femoral ICC = 0.75; 95% CI, 0.39–0.95) and both methods showed almost perfect intraobserver agreement in reproducibility (acetate cup ICC = 0.82; 95% CI, 0.66–0.97; acetate femoral ICC = 0.86; 95% CI, 0.74–0.97; digital cup ICC = 0.82; 95% CI, 0.68–0.97; digital femoral ICC = 0.88; 95% CI, 0.77–1.0). Acetate templating could be performed more quickly (acetate mean 119 seconds; range, 37–220 seconds versus 154 seconds; range, 73–343 seconds; p < 0.001).

Conclusions

Acetate onlay templating on digitally calibrated images can be a reliable substitute for digital templating using specialized software. It is quicker to perform and much less expensive. Hospitals and practices need not purchase expensive software, particularly at lower volume centers.

Level of Evidence

Level III, diagnostic study.     

A Comparison of the Efficacy of Various Antioxidants on the Oxidative Stability of Irradiated Polyethylene

Background

Ultrahigh-molecular-weight polyethylene (UHMWPE) is subjected to radiation crosslinking to form highly crosslinked polyethylene (HXLPE), which has improved wear resistance. First-generation HXLPE was subjected to thermal treatment to reduce or quench free radicals that can induce long-term oxidative degeneration. Most recently, antioxidants have been added to HXLPE to induce oxidative resistance rather than by thermal treatment. However, antioxidants can interfere with the efficiency of radiation crosslinking.

Questions/purposes

We sought to identify (1) which antioxidant from among those tested (vitamin E, β-carotene, butylated hydroxytoluene, or pentaerythritol tetrakis [methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate]) causes the least reduction of crosslinking; (2) which promotes the greatest oxidative stability; and (3) which had the lowest ratio of oxidation index to crosslink density.

Methods

Medical-grade polyethylene (PE) resin was blended with 0.1 weight % of the following stabilizers: alpha tocopherol (vitamin E), β-carotene, butylated hydroxytoluene (BHT), and pentaerythritol tetrakis [methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (a hindered phenol antioxidant [HPAO]). These blends were compression-molded into sheets and subjected to electron beam irradiation to a dose of 100 kGy. Equilibrium swelling experiments were conducted to calculate crosslink density. Each PE was subjected to accelerated aging for a period of 2 weeks and Fourier transform infrared spectroscopy was used to measure the maximum oxidation. Statistical analysis was conducted using analysis of variance with Fisher’s protected least significant difference in which a p value of < 0.05 was used to define a significant difference.

Results

The least reduction of crosslinking in antioxidant-containing HXLPE was observed with HPAO, which had a crosslink density (n = 6) of 0.167 (effect size [ES] = 0.87; 95% confidence interval [CI], 0.162–0.173) mol/dm³ compared with 0.139 (ES = 1.57; 95% CI, 0.132–0.146) mol/dm³ (p = 0.020) for BHT, 0.131 (ES = 1.77; 95% CI, 0.123–0.139) mol/dm³ (p = 0.004) for β-carotene, and 0.130 (ES = 1.79; 95% CI, 0.124–0.136) mol/dm³ (p = 0.003) for vitamin E, whereas pure HXLPE had a crosslink density of 0.203 (95% CI, 0.170–0.235) mol/dm³ (p = 0.005). BHT-PE had an oxidation index of 0.21 (ES = 13.14; 95% CI, 0.19–0.22) followed by HPAO-PE, vitamin E-PE and β-carotene-PE, which had oxidation indices of 0.28 (ES = 9.68; 95% CI, 0.28–0.29), 0.29 (ES = 9.59; 95% CI, 0.27–0.30), and 0.35 (ES = 6.68; 95% CI, 0.34–0.37), respectively (p < 0.001 for all groups). BHT-PE had the lowest ratio of oxidation index to crosslink density of the materials tested (1.49, ES = 1.94; 95% CI, 1.32–1.66) followed by HPAO-PE (1.70, ES = 1.52; 95% CI, 1.61–1.80), vitamin E-PE (2.21, ES = 0.52; 95% CI, 2.05–2.38), and β-carotene-PE (2.69, ES = -0.43; 95% CI, 2.46–2.93) compared with control PE (2.47, 95% CI, 2.07–2.88) with β-carotene (p = 0.208) and vitamin E (p = 0.129) not being different from the control.

Conclusions

BHT-modified HXLPE was found in this study to have the lowest oxidation index as well as the lowest ratio of oxidation index to crosslink density compared with vitamin E, HPAO, and β-carotene-modified HXLPEs. More comprehensive studies are required such as wear testing using joint simulators as well as biocompatibility studies before BHT-modified HXLPE can be considered for clinical use.

Clinical Relevance

BHT is a synthetic antioxidant commonly used in the polymer industry to prevent long-term oxidative degradation and has been approved by the FDA for use in cosmetics and foodstuffs. It may be an attractive potential stabilizer for HXLPE in total joint replacements.     

A History of Treated Periprosthetic Joint Infection Increases the Risk of Subsequent Different Site Infection

Background

After the successful treatment of periprosthetic joint infection (PJI), patients may present with degenerative joint disease in another joint with symptoms severe enough to warrant arthroplasty. However, it is not known whether patients with a history of treated PJI at one site will have an increased risk of PJI in the second arthroplasty site.

Questions/purposes

The primary objective of this study is to determine if there is a difference in the risk of developing a PJI after a second total hip arthroplasty (THA) or total knee arthroplasty (TKA) in patients who have had a previous PJI at another anatomic site compared with patients who have had no history of PJI. The secondary objective is to determine other potential risk factors that may predict PJI at the site of the second arthroplasty.

Methods

A retrospective matched cohort study was performed to identify all patients at four academic institutions successfully treated for PJI who subsequently underwent a second primary THA or TKA (n = 90), constituting our study group. Patients were matched (one-to-one) to control subjects who had no history of PJI after their first arthroplasty (n = 90); they were matched based on age, sex, diabetic status, BMI, American Society of Anesthesiologists, institution, joint of interest, and year of surgery (± 2 years). We compared the case and control groups to determine whether a prior infection increased the relative risk of a subsequent PJI at another anatomic site. To identify other potential risk factors for subsequent PJI, a subgroup univariate analysis of our study group (n = 90) was performed. To identify other potential risk factors for subsequent PJI, a subgroup univariate analysis of our study group (n = 90) was performed.

Results

Patients with a history of PJI had a greater risk of developing PJI in a subsequent THA or TKA (10 of 90 versus zero of 90 in the control group; relative risk, 21.00; 95% confidence interval [CI], 1.25–353.08; p = 0.035). Excluding PJI, we identified no other factors associated with a second joint infection. In patients with a history of PJI, a second PJI occurred more frequently in female patients (female: nine of 10 [90%] versus female: 40 of 80 [50%]; odds ratio [OR], 8.83; 95% CI, 1.13–403.33; p = 0.02) and in those whose initial infection was a staphylococcal species (subsequent PJI seven of 10 [70%] versus no subsequent PJI 28 of 80 [35%]; OR, 4.26; 95% CI, 0.89–27.50; p = 0.04).

Conclusions

A history of PJI predisposes patients to subsequent PJI in primary THA or THA. Patients and surgeons must be aware of the higher risk of this devastating complication before proceeding with a second arthroplasty.

Level of Evidence

Level III, prognostic study.     

What Is the Impact of Comorbidities on Self-rated Hand Function in Patients With Symptomatic Trapeziometacarpal Arthritis?

Background

The thumb trapeziometacarpal joint is one of the most common sites of arthritic degeneration prompting specialty care. Surgical treatment algorithms are based on radiographic arthritic progression. However, the pain and disability attributable to trapeziometacarpal arthritis do not correlate with arthritic stage, and depression has independently predicted poorer self-rated hand function both at baseline and after treatment in patients’ atraumatic hand conditions.

Questions/purposes

(1) Does thumb trapeziometacarpal osteoarthritis impact both self-perceived general health and hand function? (2) Do depression and other comorbid conditions differentially impact patient-rated hand function based on the presence or absence of symptomatic trapeziometacarpal arthritis? (3) How do disease-specific, patient demographics and comorbid conditions impact self-reported hand function in patients with trapeziometacarpal osteoarthritis?

Methods

This cross-sectional study compared patients with symptomatic trapeziometacarpal osteoarthritis (n = 47) with matched control subjects without a symptomatic hand condition (n = 47). All participants self-reported medical (including depression) and musculoskeletal comorbidities and completed the SF-36 and the Michigan Hand Questionnaire (MHQ). Bivariate statistical analyses contrasted the patients with trapeziometacarpal osteoarthritis to control subjects. Linear regression modeling determined the impact of subject demographic data, comorbidity burden, and examination findings on total MHQ scores in patients with trapeziometacarpal arthritis.

Results

Patients with scored trapeziometacarpal osteoarthritis indicated poorer perceived general health on the SF-36 categories of limitations resulting from physical health (52 ± 29 versus 71 ± 31, mean difference 19 [95% confidence interval {CI}, 7–31], p = 0.003) and limitations resulting from emotional problems (50 ± 27 versus 67 ± 50, mean difference 17 [95% CI, 3–33], p = 0.022) compared with control subjects. Self-reported depression was associated with worse hand function (total MHQ score) in patients with trapeziometacarpal arthritis (69 ± 20 versus 49 ± 22: mean difference −20 [95% CI, −5 to−36], p = 0.012) but not in control patients (90 ± 13 versus 84 ± 20: mean difference −5 [95% CI, −8 to 19], p = 0.404). In multivariate modeling, depression (β −20, [95% CI, −5 to −34], p = 0.009) and upper extremity comorbidities (β −25, [95% CI, −10 to −40], p = 0.002) were both associated with reduced total MHQ scores in patients with trapeziometacarpal osteoarthritis, and those factors accounted for 34% of the variance in the MHQ score.

Conclusions

When interpreting patient-rated hand disability in patients presenting with symptomatic trapeziometacarpal osteoarthritis, scores should be interpreted after accounting for the presence of depression and upper extremity comorbidities.

Level of Evidence

Level III, prognostic study.     

Can the Ream and Run Procedure Improve Glenohumeral Relationships and Function for Shoulders With the Arthritic Triad?

Background

The arthritic triad of glenoid biconcavity, glenoid retroversion, and posterior displacement of the humeral head on the glenoid is associated with an increased risk of failure of total shoulder joint replacement. Although a number of glenohumeral arthroplasty techniques are being used to manage this complex pathology, problems with glenoid component failure remain. In that the ream and run procedure manages arthritic pathoanatomy without a glenoid component, we sought evidence that this procedure can be effective in improving the centering of the humeral head contact on the glenoid and in improving the comfort and function of shoulders with the arthritic triad without the risk of glenoid component failure.

Questions/purposes

We asked, for shoulders with the arthritic triad, whether the ream and run procedure could improve glenohumeral relationships as measured on standardized axillary radiographs and patient-reported shoulder comfort and function as recorded by the Simple Shoulder Test.

Methods

Between January 1, 2006 and December 14, 2011, we performed 531 primary anatomic glenohumeral arthroplasties for arthritis, of which 221 (42%) were ream and run procedures. Of these, 30 shoulders in 30 patients had the ream and run procedure for the arthritic triad and had two years of clinical and radiographic follow-up. These 30 shoulders formed the basis for this case series. The average age of the patients was 56 ± 8 years; all but one were male. Two of the 30 patients requested revision to total shoulder arthroplasty within the first year after their ream and run procedure because of their dissatisfaction with their rehabilitation progress. For the 28 shoulders not having had a revision, we determined on the standardized axillary views before and after surgery the glenoid type, glenoid version (90° minus the angle between the plane of the glenoid face and the plane of the body of the scapula), and location of the humeral contact point with respect to the anteroposterio dimension of the glenoid (the ratio of the distance from the anterior glenoid lip to the contact point divided by the distance between the anterior and posterior glenoid lips). We also recorded the patient’s self-assessed shoulder comfort and function before and after surgery using the 12 questions of the Simple Shoulder Test.

Results

For the 28 unrevised shoulders the mean followup was 3.0 years (range, 2–9.2 years). In these patients, the ream and run procedure resulted in improved centering of the humeral head on the face of the glenoid (preoperative: 75% ± 7% posterior; postoperative: 59% ± 10% posterior; mean difference 16% [95% CI, 13%–19%]; p < 0.001), notably this improved centering was achieved without a significant change in the glenoid version. Patient-reported function was improved (preoperative Simple Shoulder Test: 5 ± 3, postoperative Simple Shoulder Test: 10 ± 4, mean difference 5 [95% CI, 4–6], p < 0.001).

Conclusions

For shoulders with the arthritic triad, the ream and run procedure can provide improvement in humeral centering on the glenoid and in patient-reported shoulder comfort and function without the risk of glenoid component failure. In that ream and run is a new procedure, substantial additional clinical research with long-term follow-up is needed to define specifically the shoulder characteristics, the patient characteristics and the technical details that are most likely to lead to durable improvements in the comfort and function of shoulders with the challenging pathology known as the arthritic triad.

Level of Evidence

Level IV, therapeutic study.