Does the Subtalar Joint Compensate for Ankle Malalignment in End-stage Ankle Arthritis?

BackgroundPatients with ankle arthritis often present with concomitant hindfoot deformity, which may involve the tibiotalar and subtalar joints. However, the possible compensatory mechanisms of these two mechanically linked joints are not well known.Questions/purposesIn this study we sought to (1) compare ankle and hindfoot alignment of our study cohort with end-stage ankle arthritis with that of a control group; (2) explore the frequency of compensated malalignment between the tibiotalar and subtalar joints in our study cohort; and (3) assess the intraobserver and interobserver reliability of classification methods of hindfoot alignment used in this study.MethodsBetween March 2006 and September 2013, we performed 419 ankle arthrodesis and ankle replacements (380 patients). In this study, we evaluated radiographs for 233 (56%) ankles (226 patients) which met the following inclusion criteria: (1) no prior subtalar arthrodesis; (2) no previously failed total ankle replacement or ankle arthrodesis; (3) with complete conventional radiographs (all three ankle views were required: mortise, lateral, and hindfoot alignment view). Ankle and hindfoot alignment was assessed by measurement of the medial distal tibial angle, tibial talar surface angle, talar tilting angle, tibiocalcaneal axis angle, and moment arm of calcaneus. The obtained values were compared with those observed in the control group of 60 ankles from 60 people. Only those without obvious degenerative changes of the tibiotalar and subtalar joints and without previous surgeries of the ankle or hindfoot were included in the control group. Demographic data for the patients with arthritis and the control group were comparable (sex, p = 0.321; age, p = 0.087). The frequency of compensated malalignment between the tibiotalar and subtalar joints, defined as tibiocalcaneal angle or moment arm of the calcaneus being greater or smaller than the same 95% CI statistical cutoffs from the control group, was tallied. All ankle radiographs were independently measured by two observers to determine the interobserver reliability. One of the observers evaluated all images twice to determine the intraobserver reliability.ResultsThere were differences in medial distal tibial surface angle (86.6° ± 7.3° [95% CI, 66.3°–123.7°) versus 89.1° ± 2.9° [95% CI, 83.0°–96.3°], p < 0.001), tibiotalar surface angle (84.9° ± 14.4° [95% CI, 45.3°–122.7°] versus 89.1° ± 2.9° [95% CI, 83.0°–96.3°], p < 0.001), talar tilting angle (−1.7° ± 12.5° [95% CI, −41.3°–30.3°) versus 0.0° ± 0.0° [95% CI, 0.0°–0.0°], p = 0.003), and tibiocalcaneal axis angle (−7.2° ± 13.1° [95% CI, −57°–33°) versus −2.7° ± 5.2° [95% CI, −13.3°–9.0°], p < 0.001) between patients with ankle arthritis and the control group. Using the classification system based on the tibiocalcaneal angle, there were 62 (53%) and 22 (39%) compensated ankles in the varus and valgus groups, respectively. Using the classification system based on the moment arm of the calcaneus, there were 68 (58%) and 20 (35%) compensated ankles in the varus and valgus groups, respectively. For all conditions or methods of measurement, patients with no or mild degenerative change of the subtalar joint have a greater likelihood of compensating coronal plane deformity of the ankle with arthritis (p < 0.001–p = 0.032). The interobserver and intraobserver reliability for all radiographic measurements was good to excellent (the correlation coefficients range from 0.820 to 0.943).ConclusionsSubstantial ankle malalignment, mostly varus deformity, is common in ankles with end-stage osteoarthritis. The subtalar joint often compensates for the malaligned ankle in static weightbearing.

Level of Evidence

Level III, diagnostic study.     

How Do Different Anterior Tibial Tendon Transfer Techniques Influence Forefoot and Hindfoot Motion?

Background

Idiopathic clubfoot correction is commonly performed using the Ponseti method and is widely reported to provide reliable results. However, a relapsed deformity may occur and often is treated in children older than 2.5 years with repeat casting, followed by an anterior tibial tendon transfer. Several techniques have been described, including a whole tendon transfer using a two-incision technique or a three-incision technique, and a split transfer, but little is known regarding the biomechanical effects of these transfers on forefoot and hindfoot motion.

Questions/purpose

We used a cadaveric foot model to test the effects of three tibialis anterior tendon transfer techniques on forefoot positioning and production of hindfoot valgus.

Methods

Ten fresh-frozen cadaveric lower legs were used. We applied 150 N tension to the anterior tibial tendon, causing the ankle to dorsiflex. Three-dimensional motions of the first metatarsal, calcaneus, and talus relative to the tibia were measured in intact specimens, and then repeated after each of the three surgical techniques.

Results

Under maximum dorsiflexion, the intact specimens showed 6° (95% CI, 2.2°–9.4°) forefoot supination and less than 3° (95% CI, 0.4°–5.3°) hindfoot valgus motion. All three transfers provided increased forefoot pronation and hindfoot valgus motion compared with intact specimens: the three-incision whole transfer provided 38° (95% CI, 33°–43°; p < 0.01) forefoot pronation and 10° (95% CI, 8.5°–12°; p < 0.01) hindfoot valgus; the split transfer, 28° (95% CI, 24°–32°; p < 0.01) pronation, 9° (95% CI, 7.5°–11°; p < 0.01) valgus; and the two-incision transfer, 25° (95% CI, 20°–31°; p < 0.01) pronation, 6° (95% CI, 4.2°–7.8°; p < 0.01) valgus.

Conclusion

All three techniques may be useful and deliver varying degrees of increased forefoot pronation, with the three-incision whole transfer providing the most forefoot pronation. Changes in hindfoot motion were small.

Clinical Relevance

Our study results show that the amount of forefoot pronation varied for different transfer methods. Supple dynamic forefoot supination may be treated with a whole transfer using a two-incision technique to avoid overcorrection, while a three-incision technique or a split transfer may be useful for more resistant feet. Confirmation of these findings awaits further clinical trials.     

Open posterior approach for tibiotalar arthrodesis

Traumatic injury to the ankle and hindfoot often results in tibiotalar or subtalar arthritis. The associated joint pain, stiffness, and deformity may be difficult to treat with conservative measures. For such problems, arthrodesis of the ankle or hindfoot joints is the mainstay of treatment. This article discusses the application of the posterior approach to complete a tibiotalar and tibiotalocalcaneal arthrodesis as well as its use for converting a failed total ankle arthroplasty to an arthrodesis.     

Implant Design Variations in Reverse Total Shoulder Arthroplasty Influence the Required Deltoid Force and Resultant Joint Load

Background

Reverse total shoulder arthroplasty (RTSA) is widely used; however, the effects of RTSA geometric parameters on joint and muscle loading, which strongly influence implant survivorship and long-term function, are not well understood. By investigating these parameters, it should be possible to objectively optimize RTSA design and implantation technique.

Questions/purposes

The purposes of this study were to evaluate the effect of RTSA implant design parameters on (1) the deltoid muscle forces required to produce abduction, and (2) the magnitude of joint load and (3) the loading angle throughout this motion. We also sought to determine how these parameters interacted.

Methods

Seven cadaveric shoulders were tested using a muscle load-driven in vitro simulator to achieve repeatable motions. The effects of three implant parameters—humeral lateralization (0, 5, 10 mm), polyethylene thickness (3, 6, 9 mm), and glenosphere lateralization (0, 5, 10 mm)—were assessed for the three outcomes: deltoid muscle force required to produce abduction, magnitude of joint load, and joint loading angle throughout abduction.

Results

Increasing humeral lateralization decreased deltoid forces required for active abduction (0 mm: 68% ± 8% [95% CI, 60%–76% body weight (BW)]; 10 mm: 65% ± 8% [95% CI, 58%–72 % BW]; p = 0.022). Increasing glenosphere lateralization increased deltoid force (0 mm: 61% ± 8% [95% CI, 55%–68% BW]; 10 mm: 70% ± 11% [95% CI, 60%–81% BW]; p = 0.007) and joint loads (0 mm: 53% ± 8% [95% CI, 46%–61% BW]; 10 mm: 70% ± 10% [95% CI, 61%–79% BW]; p < 0.001). Increasing polyethylene cup thickness increased deltoid force (3 mm: 65% ± 8% [95% CI, 56%–73% BW]; 9 mm: 68% ± 8% [95% CI, 61%–75% BW]; p = 0.03) and joint load (3 mm: 60% ± 8% [95% CI, 53%–67% BW]; 9 mm: 64% ± 10% [95% CI, 56%–72% BW]; p = 0.034).

Conclusions

Humeral lateralization was the only parameter that improved joint and muscle loading, whereas glenosphere lateralization resulted in increased loads. Humeral lateralization may be a useful implant parameter in countering some of the negative effects of glenosphere lateralization, but this should not be considered the sole solution for the negative effects of glenosphere lateralization. Overstuffing the articulation with progressively thicker humeral polyethylene inserts produced some adverse effects on deltoid muscle and joint loading.

Clinical Relevance

This systematic evaluation has determined that glenosphere lateralization produces marked negative effects on loading outcomes; however, the importance of avoiding scapular notching may outweigh these effects. Humeral lateralization’s ability to decrease the effects of glenosphere lateralization was promising but further investigations are required to determine the effects of combined lateralization on functional outcomes including range of motion.     

What Are the Biomechanical Effects of Half-pin and Fine-wire Configurations on Fracture Site Movement in Circular Frames?

Background

Fine-wire circular frame (Ilizarov) fixators are hypothesized to generate favorable biomechanical conditions for fracture healing, allowing axial micromotion while limiting interfragmentary shear. Use of half-pins increases fixation options and may improve patient comfort by reducing muscle irritation, but they are thought to induce interfragmentary shear, converting beam-to-cantilever loading. Little evidence exists regarding the magnitude and type of strain in such constructs during weightbearing.

Questions/purposes

This biomechanical study was designed to investigate the levels of interfragmentary strain occurring during physiologic loading of an Ilizarov frame and the effect on this of substituting half-pins for fine-wires.

Methods

The “control” construct was comprised of a four-ring all fine-wire construct with plain wires at 90°-crossing angles in an entirely unstable acrylic pipe synthetic fracture model. Various configurations, substituting half-pins for wires, were tested under levels of axial compression, cantilever bending, and rotational torque simulating loading during gait. In total three frames were tested for each of five constructs, from all fine-wire to all half-pin.

Results

Substitution of half-pins for wires was associated with increased overall construct rigidity and reduced planar interfragmentary motion, most markedly between all-wire and all-pin frames (axial: 5.9 mm ± 0.7 vs 4.2 mm ± 0.1, mean difference, 1.7 mm, 95% CI, 0.8–2.6 mm, p < 0.001; torsional: 1.4% ± 0.1 vs 1.1% ± 0.0 rotational shear, mean difference, 0.3%, 95% CI, 0.1%–0.5%, p = 0.011; bending: 7.5° ± 0.1 vs 3.4° ± 0.1, mean difference, −4.1°, 95% CI, −4.4° to −3.8°, p < 0.001). Although greater transverse shear strain was observed during axial loading (0.4% ± 0.2 vs 1.9% ± 0.1, mean difference, 1.4%, 95% CI, 1.0%–1.9%, p < 0.001), this increase is unlikely to be of clinical relevance given the current body of evidence showing bone healing under shear strains of up to 25%. The greatest transverse shear was observed under bending loads in all fine-wire frames, approaching 30% (29% ± 1.9). This was reduced to 8% (±0.2) by incorporation of sagittal plane half-pins and 7% (±0.2) in all half-pin frames (mean difference, −13.2% and −14.0%, 95% CI, −16.6% to 9.7% and −17.5% to −10.6%, both p < 0.001).

Conclusions

Appropriate use of half-pins may reduce levels of shear strain on physiologic loading of circular frames without otherwise altering the fracture site mechanical environment at levels likely to be clinically important. Given the limitations of a biomechanical study using a symmetric and uniform synthetic bone model, further clinical studies are needed to confirm these conclusions in vivo.

Clinical Relevance

The findings of this study add to the overall understanding of the mechanics of circular frame fixation and, if replicated in the clinical setting, may be applied to the preoperative planning of frame treatment, particularly in unstable fractures or bone transport where control of shear strain is a priority.     

A radiographic and clinical comparison of reamer–irrigator–aspirator versus iliac crest bone graft in ankle arthrodesis

Purpose

We evaluated radiographic fusion at follow-up and complication rates in patients who had either iliac crest (ICBG) or femoral reamer–irrigator–aspirator (RIA) bone graft for tibiotalar fusion.

Methods

We retrospectively reviewed charts and radiographs of all patients who had a tibiotalar fusion from August 2007 to February 2011. Records were analysed for patient demographics, complications, and clinical symptoms. Radiographs were reviewed in sequential order by two fellowship-trained foot and ankle surgeons and one orthopaedic surgeon who specialises in foot and ankle surgery to determine radiographic fusion at routine follow-up. Patients were contacted to determine current visual analog scores (VAS) at their graft site.

Results

Mean patient age was 49.4 ± 12.1 years in the RIA group and 49.3 ± 15.4 years in the ICBG group (p = .97). Pre-operative characteristics showed no significant differences between groups. The ICBG group had significantly more nonunions than the RIA group (six vs. one, p = 0.04). Two patients in the ICBG had chronic pain at their graft site based on their VAS score; there were none in the RIA group. Radiographic fusion at follow-up was similar between groups, with no significant difference (12.48 ± 3.85 weeks vs.12.21 ± 3.19 weeks, p = .80).

Conclusions

There was a significantly higher nonunion rate in the ICBG group, but both groups had a solid radiographic bony fusion at similar follow-up time points. Our results suggest RIA bone graft is a viable alternative to ICBG for tibiotalar fusion.     

Does Preparation of the Subtalar Joint for Primary Union Affect Clinical Outcome in Patients Undergoing Intramedullary Nail for Rheumatoid Arthritis of the Hindfoot and Ankle?

This study aimed to evaluate whether preparation of the subtalar joint affects the clinical outcomes after tibiotalocalcaneal arthrodesis using an intramedullary nail with fins for rheumatoid ankle/hindfoot deformity. Fifty-three joints in 51 patients who underwent tibiotalocalcaneal arthrodesis using an intramedullary nail with fins for rheumatoid arthritis at 2 institutions were included. Ten patients were male and 41 were female, with a mean age at surgery and follow-up period of 61.3 years and 71.6 months, respectively. Radiographic bone union was evaluated at the most recent visit. Univariate and multivariable analyses were performed to determine the risk factors associated with nonunion. The mean postoperative Japanese Society for Surgery of the Foot ankle/hindfoot scale was 65.3 (range, 5–84). The tibiotalar nonunion rate was 0%, whereas the subtalar nonunion rate was 43.3% (23 joints). Revision surgery was performed in 5, all of which were due to painful subtalar nonunion. Absence of subtalar curettage and earlier postoperative weightbearing were significantly associated with subtalar nonunion (p = .0451 and p = .0438, respectively). Subtalar nonunion after tibiotalocalcaneal arthrodesis for rheumatoid hindfoot is associated with higher revision rate. To decrease the risk of subtalar nonunion after tibiotalocalcaneal arthrodesis with an intramedullary nail in rheumatoid patients, curettage for the subtalar joint should be performed, and full weightbearing should be delayed until at least 26 days postoperatively.     

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.     

Expanding Indications of Primary Arthrodesis in Selected Individuals for Managing Complex Hindfoot Trauma During COVID-19 Pandemic

BackgroundDuring the COVID-19 pandemic, public health measures to encourage social distancing have been implemented, including cancellation of outdoor activities, organized sports, and schools/colleges. Neglected hindfoot fractures have emerged as a consequence with increased frequency. Similarly, complex ankle and pilon fractures that require staged management, prolonged hospital stay, and soft-tissue care have emerged as a potential concern as prolonged exposure to healthcare setting adds to risk of acquiring as well as transmitting COVID-19 infection. The authors present their experience with expanding these indications for hindfoot arthrodesis as they encounter a greater number of neglected ankle and hindfoot trauma.MethodsThis was a retrospective observational study of collected data from the trauma unit of our hospital. Inclusion criteria included all trauma classified by the AO/OTA as occurring at locations 43, and who underwent subtalar and ankle arthrodesis. This included distal tibia, malleolar, talus, and calcaneus fractures. These patients were followed up to at least 6 months till complete fracture union.ResultsA total of 18 patients underwent arthrodesis of either the ankle or subtalar joint between March and October 2020. Mean age of patients undergoing arthrodesis of the hindfoot was 69.2 years (43–84 years). Indications for the procedure included Displaced and comminuted intra-articular distal tibia fractures in elderly (6 patients), Malunited ankle fractures (2 patients), Neglected Ankle fractures managed conservatively (3 patients), Calcaneus fractures (5 patients), and neglected Talus body fracture (2 patients). All patients were followed up to at least 6 months and everyone went onto successful painless union between 3 and 6 months of the arthrodesis procedure without any significant complications.ConclusionIn summary, COVID-19 pandemic has led to a change in paradigm of trauma management and foot and ankle management is no different than other musculoskeletal trauma systems. The authors propose an expansion of indications for hindfoot arthrodesis in managing complex hindfoot trauma in pandemic situation.     

Global Rating Scales and Motion Analysis Are Valid Proficiency Metrics in Virtual and Benchtop Knee Arthroscopy Simulators

Background

Work-hour restrictions and fatigue management strategies in surgical training programs continue to evolve in an effort to improve the learning environment and promote safer patient care. In response, training programs must reevaluate how various teaching modalities such as simulation can augment the development of surgical competence in trainees. For surgical simulators to be most useful, it is important to determine whether surgical proficiency can be reliably differentiated using them. To our knowledge, performance on both virtual and benchtop arthroscopy simulators has not been concurrently assessed in the same subjects.

Questions/purposes

(1) Do global rating scales and procedure time differentiate arthroscopic expertise in virtual and benchtop knee models? (2) Can commercially available built-in motion analysis metrics differentiate arthroscopic expertise? (3) How well are performance measures on virtual and benchtop simulators correlated? (4) Are these metrics sensitive enough to differentiate by year of training?

Methods

A cross-sectional study of 19 subjects (four medical students, 12 residents, and three staff) were recruited and divided into 11 novice arthroscopists (student to Postgraduate Year [PGY] 3) and eight proficient arthroscopists (PGY 4 to staff) who completed a diagnostic arthroscopy and loose-body retrieval in both virtual and benchtop knee models. Global rating scales (GRS), procedure times, and motion analysis metrics were used to evaluate performance.

Results

The proficient group scored higher on virtual (14 ± 6 [95% confidence interval {CI}, 10–18] versus 36 ± 5 [95% CI, 32–40], p < 0.001) and benchtop (16 ± 8 [95% CI, 11–21] versus 36 ± 5 [95% CI, 31–40], p < 0.001) GRS scales. The proficient subjects completed nearly all tasks faster than novice subjects, including the virtual scope (579 ±169 [95% CI, 466–692] versus 358 ± 178 [95% CI, 210–507] seconds, p = 0.02) and benchtop knee scope + probe (480 ± 160 [95% CI, 373–588] versus 277 ± 64 [95% CI, 224–330] seconds, p = 0.002). The built-in motion analysis metrics also distinguished novices from proficient arthroscopists using the self-generated virtual loose body retrieval task scores (4 ± 1 [95% CI, 3–5] versus 6 ± 1 [95% CI, 5–7], p = 0.001). GRS scores between virtual and benchtop models were very strongly correlated (ρ = 0.93, p < 0.001). There was strong correlation between year of training and virtual GRS (ρ = 0.8, p < 0.001) and benchtop GRS (ρ = 0.87, p < 0.001) scores.

Conclusions

To our knowledge, this is the first study to evaluate performance on both virtual and benchtop knee simulators. We have shown that subjective GRS scores and objective motion analysis metrics and procedure time are valid measures to distinguish arthroscopic skill on both virtual and benchtop modalities. Performance on both modalities is well correlated. We believe that training on artificial models allows acquisition of skills in a safe environment. Future work should compare different modalities in the efficiency of skill acquisition, retention, and transferability to the operating room.     

Total ankle arthroplasty versus ankle arthrodesis. Comparison of sports, recreational activities and functional outcome

Purpose

Ankle arthrodesis (AAD) and total ankle replacement (TAR) are the major surgical treatment options for severe ankle arthritis. There is an ongoing discussion in the orthopaedic community whether ankle arthrodesis or ankle fusion should be the treatment of choice for end stage osteoarthritis. The purpose of this study was to compare the participation in sports and recreational activities in patients who underwent either AAD or TAR for end-stage osteoarthritis of the ankle.

Methods

A total of 41 patients (21 ankle arthrodesis /20 TAR) were examined at 34.5 (SD18.0) months after surgery. At follow-up, pre- and postoperative participation in sports and recreational activities has been assessed. Activity levels were determined using the ankle activity score according to Halasi et al. and the University of California at Los Angeles (UCLA) activity scale. Clinical and functional outcome was assessed using the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score. The percentage of patients participating in sports and recreational activities, UCLA score and AOFAS score were compared between both treatment groups.

Results

In the AAD group 86% were active in sports preoperatively and in the TAR group this number was 76%. Postoperatively in both groups 76% were active in sports (AAD, p = 0.08). The UCLA score was 7.0 (± 1.9) in the AAD group and 6.8 (± 1.8) in the TAR group (p = 0.78). The AOFAS score reached 75.6 (± 14) in the AAD group and 75.6 (± 16) in the TAR group (p = 0.97). The ankle activity score decrease was statistically significant for both groups (p = 0.047).

Conclusions

Our study revealed no significant difference between the groups concerning activity levels, participation in sports activities, UCLA and AOFAS score. After AAD the number of patients participating in sports decreased. However, this change was not statistically significant.     

Patients Undergoing Total Shoulder Arthroplasty on the Dominant Extremity Attain Greater Postoperative ROM

Background

Total shoulder arthroplasty (TSA) provides excellent functional outcomes and pain relief in appropriately selected patients. Although it is known to affect other shoulder conditions, the role of hand dominance after TSA has not been reported, to our knowledge.

Questions/Purposes

We asked: (1) Does TSA of the dominant arm result in greater postoperative ROM compared with TSA of the nondominant arm? (2) Does hand dominance affect validated outcome scores after TSA?

Methods

We performed a review of all patients who underwent primary TSAs between 2008 and 2011 with a minimum of 12 months followup. During that time, one surgeon performed 156 primary TSAs. One hundred twenty-seven patients met the minimum followup requirement for this analysis (81%), whereas 29 (19%) were lost to followup. Seven patients were excluded for surgical indications other than glenohumeral osteoarthritis. A total of 58 patients underwent TSA of the dominant upper extremity and 62 underwent TSA of the nondominant upper extremity. Patient demographics, preoperative and postoperative ROM, and preoperative and postoperative outcome scores, were collected from the medical records. Student’s t-tests and chi-square tests were used for analysis. Demographics and preoperative ROM did not differ between patients undergoing TSA on the dominant or the nondominant upper extremity.

Results

Dominant-arm TSAs showed greater postoperative forward elevation and external rotation. Postoperative active forward elevation in the dominant group was 151° versus 141° in the nondominant group (mean difference, 10°; 95% CI, 1°–18°; p = 0.033). Postoperative active external rotation was 61° in the dominant group, versus 51° in the nondominant group (mean difference, 10°; 95% CI, 5°–15°; p < 0.001). Active internal rotation did not differ (dominant, 52°, nondominant, 50°; mean difference, 2°; 95% CI, −3° to 7°; p = 0.419). There were no differences in postoperative VAS (dominant, 0.9, nondominant, 1.4; mean difference, 0.5; 95% CI, −0.1 to 1.1; p = 0.129), simple shoulder test (dominant, 9.8, nondominant, 9.2; mean difference, 0.5; 95% CI, −0.5 to 1.5; p = 0.278), and American Shoulder and Elbow Surgeons scores (dominant, 84, nondominant, 80; mean difference, 4; 95% CI, −2 to 10; p = 0.211).

Conclusions

Patients who underwent TSA of their dominant upper extremity had greater postoperative active forward elevation and active external rotation compared with patients who had TSA of their nondominant upper extremity. This average difference of 10° active forward elevation and active external rotation could be useful for preoperative and postoperative counseling of patients. Regardless of hand dominance, similar functional outcomes were achieved.

Level of Evidence

Level III, therapeutic study.     

Radiographic quantification of dynamic hip screw migration

Purpose

This study aimed to propose a technique to quantify dynamic hip screw (DHS®) migration on serial anteroposterior (AP) radiographs by accounting for femoral rotation and flexion.

Methods

Femoral rotation and flexion were estimated using radiographic projections of the DHS® plate thickness and length, respectively. The method accuracy was evaluated using a synthetic femur fixed with a DHS® and positioned at pre-defined rotation and flexion settings. Standardised measurements of DHS® migration were trigonometrically adjusted for femoral rotation and flexion, and compared with unadjusted estimates in 34 patients.

Results

The mean difference between the estimated and true femoral rotation and flexion values was 1.3° (95 % CI 0.9–1.7°) and −3.0° (95 % CI – 4.2° to −1.9°), respectively. Adjusted measurements of DHS® migration were significantly larger than unadjusted measurements (p = 0.045).

Conclusion

The presented method allows quantification of DHS® migration with adequate bias correction due to femoral rotation and flexion.

Electronic supplementary material

The online version of this article (doi:10.1007/s00264-013-2146-4) contains supplementary material, which is available to authorised users.     

Poorer survival after a primary implant during revision total knee arthroplasty

Purpose

Revision total knee arthroplasty (rTKA) is a complex procedure. Depending on the degree of ligament and bone damage, either primary or revision implants are used. The purpose of this study was to compare survival rates of primary implants with revision implants when used during rTKA.

Methods

A retrospective comparative study was conducted between 1998 and 2009 during which 69 rTKAs were performed on 65 patients. Most common indications for revision were infection (30 %), aseptic loosening (25 %) and wear/osteolysis (25 %). During rTKA, a primary implant was used in nine knees and a revision implant in 60.

Results

Survival of primary implants was 100 % at one year, 73 % [95 % confidence interval (CI) 41–100] at two years and 44 % (95 % CI 7–81) at five years. Survival of revision implants was 95 % (95 % CI 89–100) at one year, 92 % (95 % CI 84–99) at two years and 92 % (95 % CI 84–99) at five years. Primary implants had a significantly worse survival rate than revision implants when implanted during rTKA [P = 0.039 (hazard ratio = 4.56, 95 % CI 1.08–19.27)].

Conclusions

Based on these results, it has to be considered whether primary implants are even an option during rTKA.