Characteristics of unsatisfactory shoulder arthroplasties

Three-dimensional imaging and templating improve glenoid implant positioning

BACKGROUND

Preoperative quantitative assessment of glenoid bone loss, selection of the glenoid component, and definition of its desired location can be challenging. Placement of the glenoid component in the desired location at the time of surgery is difficult, especially with severe glenoid pathological conditions.

METHODS

Forty-six patients were randomly assigned to three-dimensional computed tomographic preoperative templating with either standard instrumentation or with patient-specific instrumentation and were compared with a nonrandomized group of seventeen patients with two-dimensional imaging and standard instrumentation used as historical controls. All patients had postoperative three-dimensional computed tomographic metal artifact reduction imaging to measure and to compare implant position with the preoperative plan.

RESULTS

Using three-dimensional imaging and templating with or without patient-specific instrumentation, there was a significant improvement achieving the desired implant position within 5° of inclination or 10° of version when compared with two-dimensional imaging and standard instrumentation.

CONCLUSION

Three-dimensional assessment of glenoid anatomy and implant templating and the use of these images at the time of surgery improve the surgeon's ability to place the glenoid implant in the desired location.

Wear and damage of articular cartilage with friction against orthopedic implant materials

The objective of this study was to measure the wear response of immature bovine articular cartilage tested against glass or alloys used in hemiarthroplasties. Two cobalt chromium alloys and a stainless steel alloy were selected for these investigations. The surface roughness of one of the cobalt chromium alloys was also varied within the range considered acceptable by regulatory agencies. Cartilage disks were tested in a configuration that promoted loss of interstitial fluid pressurization to accelerate conditions believed to occur in hemiarthroplasties. Results showed that considerably more damage occurred in cartilage samples tested against stainless steel (10 nm roughness) and low carbon cobalt chromium alloy (27 nm roughness) compared to glass (10 nm) and smoother low or high carbon cobalt chromium (10 nm). The two materials producing the greatest damage also exhibited higher equilibrium friction coefficients. Cartilage damage occurred primarily in the form of delamination at the interface between the superficial tangential zone and the transitional middle zone, with much less evidence of abrasive wear at the articular surface. These results suggest that cartilage damage from frictional loading occurs as a result of subsurface fatigue failure leading to the delamination. Surface chemistry and surface roughness of implant materials can have a significant influence on tissue damage, even when using materials and roughness values that satisfy regulatory requirements.

Conversion of stemmed hemi- or total to reverse total shoulder arthroplasty: advantages of a modular stem design

BACKGROUND

If revision of a failed anatomic hemiarthroplasty or total shoulder arthroplasty is uncertain to preserve or restore satisfactory rotator cuff function, conversion to a reverse total shoulder arthroplasty has become the preferred treatment, at least for elderly patients. However, revision of a well-fixed humeral stem has the potential risk of loss of humeral bone stock, nerve injury, periprosthetic fracture, and malunion or nonunion of a humeral osteotomy with later humeral component loosening.

QUESTIONS/PURPOSES

The purposes of this study were to determine whether preservation of a modular stem is associated with (1) less blood loss and operative time; (2) fewer perioperative and postoperative complications, including reoperations and revisions; and/or (3) improved Constant and Murley scores and subjective shoulder values for conversion to a reverse total shoulder arthroplasty compared with stem revision.

METHODS

Between 2005 and 2011, 48 hemiarthroplasties and eight total shoulder arthroplasties (total=56 shoulders; 54 patients) were converted to an Anatomical™ reverse total shoulder arthroplasty system without (n=13) or with (n=43) stem exchange. Complications and revisions for all patients were tallied through review of medical and surgical records. The outcomes scores included the Constant and Murley score and the subjective shoulder value. Complete clinical followup was available on 80% of shoulders (43 patients; 45 of 56 procedures, 32 with and 13 without stem exchange) at a minimum of 12 months (mean, 37 months; range, 12-83 months).

RESULTS

Blood loss averaged 485 mL (range, 300-700 mL; SD, 151 mL) and surgical time averaged 118 minutes (range, 90-160 minutes; SD, 21 minutes) without stem exchange and 831 mL (range, 350-2000 mL; SD, 400 mL) and 176 minutes (range, 120-300 minutes; SD, 42 minutes) with stem exchange (p=0.001). Intraoperative complications (8% versus 30%; odds ratio [OR], 5.2) and reinterventions (8% versus 14%; OR, 1.9) were substantially fewer in patients without stem exchange. The complication rate leading to dropout from the study was substantial in the stem revision group (six patients; 43 shoulders [14%]), but there were no complication-related dropouts in the stem-retaining group. If, however, such complications could be avoided, with the numbers available we detected no difference in the functional outcome between the two groups.

CONCLUSIONS

Patients undergoing revision of stemmed hemiarthroplasty or total to reverse total shoulder arthroplasty without stem exchange had less intraoperative blood loss and operative time, fewer intraoperative complications, and fewer revisions than did patients whose index revision procedures included a full stem exchange. Therefore modularity of a shoulder arthroplasty system has substantial advantages if conversion to reverse total shoulder arthroplasty becomes necessary and should be considered as prerequisite for stemmed shoulder arthroplasty systems.

LEVEL OF EVIDENCE

Level III, therapeutic study.

A novel osteotomy in shoulder joint replacement based on analysis of the cartilage/metaphyseal interface

BACKGROUND

The accuracy of reconstruction is thought to impact on functional outcome following glenohumeral joint arthroplasty. The objective of this study was to define an area of minimal anatomic variation at the cartilage/metaphyseal interface of the proximal humerus to optimize the osteotomy of the humeral head, enabling accurate reconstruction with a prosthetic component.

METHODS

Hand held digitization and 3D surface laser scanning techniques were used to digitize 24 cadaveric arms and determine the normal geometry. Each humeral head was then examined to identify the most consistent anatomical landmarks for the ideal osteotomy plane to optimize humeral component positioning.

FINDINGS

The novel, posterior referencing, osteotomy resulted in a mean increase in retroversion of only 0.4° when compared to the original geometry. A traditional anterior referencing osteotomy, by comparison, produced a mean increase in retroversion of 11°. In addition, the novel osteotomy only increased axial diameter by 0.71mm and head height by 0.02mm compared to an anterior referencing osteotomy (3.0mm and 2.7mm respectively).

INTERPRETATION

The traditional osteotomy, referencing the anterior border of the cartilage/metaphyseal interface potentially resulted in an increase in prosthetic head size and retroversion. The novel osteotomy, referencing from the posterior cartilage/metaphyseal interface enabled a more accurate recovery of head geometry. Importantly, the increase in retroversion created by the traditional osteotomy was not replicated with the novel technique. Referencing from the posterior cartilage/metaphyseal interface produced a more reliable osteotomy, more closely matching the original humeral geometry.

LEVEL OF EVIDENCE

Basic Science, Anatomic study, Computer model.

Propionibacterium persists in the skin despite standard surgical preparation

BACKGROUND

Propionibacterium acnes, which normally resides in the skin, is known to play a role in surgical site infection in orthopaedic surgery. Studies have suggested a persistence of propionibacteria on the skin surface, with rates of positive cultures ranging from 7% to 29% after surgical preparation. However, as Propionibacterium organisms normally reside in the dermal layer, these studies may underestimate the true prevalence of propionibacteria after surgical skin preparation. We hypothesized that, after surgical skin preparation, viable Propionibacterium remains in the dermis at a much higher rate than previously reported.

METHODS

Ten healthy male volunteers underwent skin preparation of the upper back with ChloraPrep (2% chlorhexidine gluconate and 70% isopropyl alcohol). Two 3-mm dermal punch biopsy specimens were obtained through the prepared skin and specifically cultured for P. acnes.

RESULTS

Seven volunteers had positive findings for Propionibacterium on dermal cultures after ChloraPrep skin preparation. The average time to positive cultures was 6.78 days.

CONCLUSIONS

This study found that Propionibacterium persists in the dermal tissue even after surface skin preparation with ChloraPrep. The 70% rate of persistence of propionibacteria after skin preparation is substantially higher than previously reported.

CLINICAL RELEVANCE

Propionibacteria are increasingly discussed as having an association with infection, implant failure, and degenerative disease. This study confirms the possibility that the dermal layer of skin may be the source of the bacteria.

Treatment of proximal humeral fractures with reverse shoulder arthroplasty in elderly patients

BACKGROUND

Proximal humeral fractures in four or even only three parts, with metaphyseal hinge distances of <8 mm, represent a serious and widely debated problem. Reduction is complex and plating is often instable, especially in elderly patients. Failures, sometimes involving necrosis of the head, are frequent. Hemiarthroplasty has long been used for 3- or 4-part complex fractures, even in young patients, although often with sub-optimal results, due to reabsorption of tuberosities. This complication has partly been overcome with reverse shoulder prostheses which, although more invasive than partial ones, may lead to less disappointing results, even in cases of reabsorption of tuberosities. We have data on a homogeneous series of patients treated with reverse shoulder arthroplasty for proximal fractures, with a maximum follow-up of 10 years. The aim of this study was mainly to identify which cases can be selected for effective treatment and which technical aspects are best to adopt.

MATERIALS AND METHODS

There were 33 patients in this study, mean age 76.6 years (range 54-85). Fractures were classified according to Neer. Surgery was undertaken on average 4.4 days after trauma. The deltopectoral approach was used. Sutures were hooked over the major and lesser tubercles for later reduction and fixation after the prosthesis had been applied. This passage was sometimes not possible in cases of serious degeneration of the rotator cuff. One day after surgery, a shoulder brace providing an abducted angle of 15° was applied for 30 days. Patients were re-assessed with DASH and Constant scores (CS), and the ratio between healthy and operated shoulders was calculated. Physical examination was followed by X-rays, mainly to evaluate and classify any infraglenoid scapular notching according to Nerot.

RESULTS

Mean follow-up was 42.3 months (range 10-121). According to the CS, mean pain was 12.6/15 (range 3-15/15), activities of daily living 16.3/20 (range 8-20/20), ROM 21.8 (range 8-32/40) and power 5.4/25 (range 2-12/25). Total mean CS was 56.4 (range 23-80/100). The mean DASH score was 49.7 (range 32-90). The ratio of the CS parameters between opposite and operated shoulders was on average 72.8 % (range 28-90 %). Long-term complications were eight cases of scapular notching (24.2 %) of which four of grade 2 (12.1 %) and four of grade 1 (12.1 %).

CONCLUSIONS

Total reverse prostheses are more invasive because they also compromise the glenoid surface of the scapula, but they do offer good stability, even in cases of damage to the rotator cuff. Reverse prostheses have great advantages as regards to ROM, allowing functional recovery, which is good in cases with re-insertion of tuberosities, and acceptable in cases when tuberosities are not re-inserted or resorbed. In our cases, the first 3 reverse prostheses lasted 10, 8.3 and 7.3 years, and we believe that they will become increasingly long-lived, so that applying them in cases of complex fractures becomes more feasible. We prefer the deltopectoral approach because it can reduce and stabilize possible intra-operative diaphyseal fractures. Possible scapular notching must be foreseen when inserting the glenosphere. We had eight cases (24.2 %), of which four were Nerot grade 1 and four were grade 2. Applying the Kirschner wire in an infero-anterior position allows the glenosphere to be lowered with a tilt of 10°. Reverse prostheses are suitable for 3- or 4-part complex proximal humeral fractures in patients over 65. Prolonged physiokinesitherapy is essential.

Three-dimensional humeral morphologic alterations and atrophy associated with obstetrical brachial plexus palsy

BACKGROUND

Obstetrical brachial plexus palsy (OBPP) is a common birth injury, resulting in severe functional losses. Yet, little is known about how OBPP affects the 3-dimensional (3D) humeral morphology. Thus, the purpose of this study was to measure the 3D humeral architecture in children with unilateral OBPP.

METHODS

Thirteen individuals (4 female and 9 male patients; mean age, 11.8 ± 3.3 years; mean Mallet score, 15.1 ± 3.0) participated in this institutional review board approved study. A 3D T1-weighted gradient-recalled echo magnetic resonance image set was acquired for both upper limbs (involved and noninvolved). Humeral size, version, and inclination were quantified from 3D humeral models derived from these images.

RESULTS

The involved humeral head was significantly less retroverted and in declination (medial humeral head pointed anteriorly and inferiorly) relative to the noninvolved side. Osseous atrophy was present in all 3 dimensions and affected the entire humerus. The inter-rater reliability was excellent (intraclass correlation coefficient, 0.96-1.00).

DISCUSSION

This study showed that both humeral atrophy and bone shape deformities associated with OBPP are not limited to the axial plane but are 3D phenomena. Incorporating information related to these multi-planar, 3D humeral deformities into surgical planning could potentially improve functional outcomes after surgery. The documented reduction in retroversion is an osseous adaptation, which may help maintain glenohumeral congruency by partially compensating for the internal rotation of the arm. The humeral head declination is a novel finding and may be an important factor to consider when one is developing OBPP management strategies because it has been shown to lead to significant supraspinatus inefficiencies and increased required elevation forces.

Soft tissue balancing in total shoulder replacement

Total shoulder arthroplasty is now capable of recreating near anatomic reproduction of native bony shoulder anatomy, but the function and longevity of anatomic shoulder replacement is dependent on a competent soft tissue envelope and adequate motoring of all musculo-tendinous units about the shoulder. Balancing the soft tissues requires understanding of the anatomy and pathology, as well as technical skills. The advent of reverse shoulder biomechanics has brought with it special requirements of understanding of the soft tissue elements still left in the shoulder despite major rotator cuff deficiency.

Increased-offset reverse shoulder arthroplasty for the treatment of failed post-traumatic humeral head replacement

BACKGROUND

Late complications after humeral head replacement (HHR) for comminuted proximal humeral fractures are common and may necessitate revision surgery. This study evaluated the outcome of revision surgery of failed post-traumatic HHR with a less medialized reverse shoulder prosthesis.

METHODS

Thirty-three patients with failed post-traumatic HHR due to rotator-cuff insufficiency and glenoid erosion, but with sufficient preservation of the glenoid bone stock to permit primary stability of an inverted glenoid implant, underwent revision using the Bayley-Walker reverse shoulder prosthesis (Stanmore Implants, Elstree, UK) and were monitored up for a mean of 31 months. Outcome measures included the Oxford Shoulder Score, subjective shoulder value, pain rating, active range of motion, and shoulder radiographs.

RESULTS

The average postrevision Oxford Shoulder Score and subjective shoulder value improved from 50 ± 6 to 29 ± 11 and from 23 ± 19 to 51 ± 23, respectively (P < .001). Pain level decreased from 6.2 ± 2.1 to 1.4 ± 2.0 (P < .001). Active forward flexion increased from 34° ± 22° to 63° ± 30° and external rotation from 11° ± 14° to 20° ± 16°(P < .01). More patients were able to use their affected arm to reach a functional triangle consisting the mouth, opposite armpit, and ipsilateral buttock after revision (24% vs 73%; P < .001). Seven patients (21%) had postrevision complications. No glenoid loosening or scapular notching occurred.

CONCLUSION

Revision of failed post-traumatic HHR with the Bayley-Walker shoulder offers reliable pain relief and improvement in shoulder function with a complication rate similar to other reverse prostheses. Nevertheless, revision shoulder arthroplasty remains challenging with a high rate of complications.

Management of failed metal-backed glenoid component in patients with bilateral total shoulder arthroplasty

Total shoulder arthroplasty (TSA) is successful in providing pain relief and functional improvements for patients with shoulder arthritis. Outcomes are directly correlated with implant position and fixation, which ultimately affects wear and longevity. Metal-backed glenoid components were introduced as an alternative to the standard cemented glenoid fixation. Early loosening and cavitary glenoid bone loss has been reported as a major complication associated with these metal-backed glenoids, which presents the surgeon with a challenging revision situation. Furthermore, failure of bilateral TSA in patients with metal-backed glenoids is extremely rare. We present two patients with early failure of bilateral TSA secondary to loosening of the metal-backed glenoids. Both patients had significant glenoid bone loss and were treated with four different types of revision techniques. A description of treatments and outcomes of both patients are reported along with the simple shoulder test and American Shoulder and Elbow Surgeons scores. One patient underwent revision to bilateral reverse prosthesis and experienced a much-improved outcome in comparison to the patient revised to a hemiarthroplasty and resection arthroplasty, for each shoulder respectively. In patients who present with failed TSA, revision to a reverse prosthesis with or without staged glenoid bone graft should be considered as an option of treatment. It is also important to rule out infection with intraoperative tissue biopsy before proceeding to revision surgery. However, in patients with catastrophic glenoid bone loss, both hemiarthroplasty and resection arthroplasty can provide an alternative treatment option, but they are associated with a poorer functional outcome and pain relief.

Short-term results of the global C.A.P. uncemented resurfacing shoulder prosthesis

The authors report the 2-year results of an uncemented resurfacing shoulder prosthesis in 47 patients with primary glenohumeral osteoarthritis who underwent a cementless humeral resurfacing arthroplasty between 2007 and 2009. Constant scores (corrected for sex and age), shoulder function, visual analog pain scales, Dutch Simple Shoulder Tests, and physical SF-12 scores improved significantly (P<.05) from preoperatively to 2 years postoperatively. Mental SF-12 scores remained the same. Complications included 1 traumatic lesser tuberosity avulsion fracture, 1 intra-articular loose body due to a fractured osteophyte, and 1 subscapularis tendon rupture. No patient required revision surgery for any reason. Cementless humeral resurfacing arthroplasty is a viable treatment option for primary glenohumeral arthritis.

Origin of propionibacterium in surgical wounds and evidence-based approach for culturing propionibacterium from surgical sites

BACKGROUND

To explore the origin of Propionibacterium in surgical wounds and to suggest an optimized strategy for culturing this organism at the time of revision surgery, we studied the presence of this organism on the skin and in the surgical wounds of patients who underwent revision arthroplasty for reasons other than apparent infection.

METHODS

Specimens were cultured in broth and on aerobic and anaerobic media. The presence and degree of positivity of Propionibacterium cultures were correlated with sex. The results of dermal and deep cultures were correlated. Times to positivity and the yields of each media type and specimen source were investigated.

RESULTS

Propionibacterium grew in twenty-three of thirty cultures of specimens obtained preoperatively from the unprepared epidermis over the area where a skin incision was going to be made for a shoulder arthroplasty; males had a greater average degree of positivity than females (p &lt; 0.002). Twelve of twenty-one male subjects and zero of twenty female subjects who had cultures of dermal specimens obtained during revision shoulder arthroplasty had positive findings for Propionibacterium (p = 0.0001). Twelve of twenty male subjects and only one of twenty female subjects had positive deep cultures (p = 0.0004). The positivity of dermal cultures for Propionibacterium was significantly associated with the positivity of deep cultures for this organism (p = 0.0001). If Propionibacterium was present in deep tissues, it was likely that it would be recovered by culture if four different specimens were obtained and cultured for a minimum of seventeen days on three different media: aerobic, anaerobic, and broth.

CONCLUSIONS

Because the surgical incision of dermal sebaceous glands may be a source of Propionibacterium in deep wounds, strategies for minimizing the risk of Propionibacterium infections may need to be directed at minimizing the contamination of surgical wounds from these bacteria residing in rather than on the skin. Obtaining at least four specimens, observing them for seventeen days, and using three types of culture media optimize the recovery of Propionibacterium at the time of revision surgery.

Humeral surface replacement for osteoarthritis

BACKGROUND AND PURPOSE

Humeral resurfacing has shown promising results for osteoarthritis, but revisions for glenoid erosion have been reported frequently. We investigated the hypothesis that preoperative glenoid wear and postoperative progress of glenoid erosion would influence the clinical outcome.

METHODS

We reviewed 61 resurfacing hemiarthroplasties (55 patients) for primary osteoarthritis. 6 patients were lost to follow-up and 5 had undergone revision arthroplasty. This left 50 shoulders in 44 patients (mean age 66 years) that were followed for mean 30 (12-44) months. Complications, revisions, and the age- and sex-related Constant score were assessed. Radiographs were evaluated for loosening and glenoid erosion according to Walch.

RESULTS

Of the 50 shoulders that were functionally assessed, the average age- and sex-related Constant score was 73%. In patients with preoperative type-B2 glenoids, at 49% it was lower than in type-A1 glenoids (81%, p = 0.03) and in type-B1 glenoids (84%, p = 0.02). The average age- and sex-related Constant score for patients with type-A2 glenoids (60%) was lower than for type-A1 and -B1 glenoids and higher than for type-B2 glenoids, but the differences were not statistically significant. In the total population of 61 shoulders, the radiographs showed postoperative glenoid erosion in 38 cases and no humeral prosthetic loosening. Revision arthroplasty was performed in 11 cases after 28 (7-69) months. The implant size had no statistically significant influence on the functional outcome. The size was considered to be adequate in 28 of the 50 functionally assessed shoulders. In 21 cases, the implant size was too large and in 1 case it was too small.

INTERPRETATION

We found frequent postoperative glenoid erosion and a high rate of revision arthroplasty after humeral resurfacing for primary osteoarthritis. Oversizing of the implants was common, but it had no statistically significant influence on the functional outcome. Inferior results were found in the presence of increased eccentric preoperative glenoid wear. Total shoulder arthroplasty should be considered in these patients.

Revision to reverse shoulder arthroplasty with retention of the humeral component

BACKGROUND

Revision in failed shoulder arthroplasty often requires removal of the humeral component with a significant risk of fracture and bone loss. Newer modular systems allow conversion from anatomic to reverse shoulder arthroplasty with retention of a well-fixed humeral stem. We report on a prospectively evaluated series of conversions from hemiarthroplasty to reverse shoulder arthroplasty.

METHODS

In 14 cases of failed hemiarthroplasty due to rotator cuff deficiency and painful pseudoparalysis (in 13 women), revision to reverse shoulder arthroplasty was performed between October 2006 and 2010, with retention of the humeral component using modular systems. Mean age at the time of operation was 70 (56-80) years. Pre- and postoperative evaluation followed a standardized protocol including Constant score, range of motion, and radiographic analysis. Mean follow-up time was 2.5 (2-5.5) years.

RESULTS

Mean Constant score improved from 9 (2-16) to 41 (17-74) points. Mean lengthening of the arm was 2.6 (0.9-4.7) cm without any neurological complications. One patient required revision due to infection.

INTERPRETATION

Modular systems allow retainment of a well-fixed humeral stem with good outcome. There is a risk of excessive humeral lengthening.

Is premorbid glenoid anatomy altered in patients with glenohumeral osteoarthritis?

BACKGROUND

Restoration of native, premorbid glenoid anatomy may be a goal in component placement during total shoulder arthroplasty. However, if patients with unilateral glenohumeral osteoarthritis are predisposed to the development of arthritis owing to abnormal native glenoid anatomy, this recommendation may be inappropriate.

QUESTIONS/PURPOSES

The purpose of this study was to determine if patients with glenohumeral osteoarthritis have abnormal premorbid glenoid version or inclination, thereby predisposing them to subsequent glenoid disorders. We specifically tested whether: (1) premorbid glenoid version or inclination in the pathologic shoulder of patients with unilateral osteoarthritis, as determined by the glenoid vault model, is different from glenoid version or inclination in the contralateral nonpathologic shoulder of these patients; (2) there are differences between glenoid version or inclination in normal cadaver shoulders and the nonpathologic side of patients with unilateral osteoarthritis; and (3) there are differences between glenoid version or inclination in normal cadaver shoulders and the premorbid glenoid version and inclination in the pathologic shoulder of patients with unilateral osteoarthritis, as determined by the glenoid vault model.

METHODS

Bilateral CT scans were obtained in 27 patients with unilateral glenohumeral osteoarthritis. Thirty normal cadaver control shoulders also underwent CT scans. Premorbid glenoid version and inclination in the pathologic shoulder, as measured by the glenoid vault model, were compared with the contralateral nonpathologic shoulder and the normal cadaver control shoulders. Glenoid version and inclination of the normal shoulders were compared with the nonpathologic side from patients with unilateral osteoarthritis. Measurements were made by two different methods using three-dimensional surgical simulation software: (1) a direct measurement technique and (2) measurements derived from placement of a glenoid vault model. Mean differences in these parameters were compared between shoulder groups using paired and unpaired Student's t-tests.

RESULTS

Premorbid glenoid version and inclination in the pathologic shoulder as measured by the vault model averaged -7° (SD, 5) and 10° (SD, 6), respectively, compared with -7° (SD, 5) and 12° (SD, 6) as directly measured on the nonpathologic side, and -7° (SD, 4) and 12° (SD, 5) as directly measured in the normal cadaver control shoulders. There were no differences in glenoid version or inclination between the normal shoulders and the nonpathologic side of patients with unilateral osteoarthritis or between these shoulders and the premorbid version and inclination of the arthritic shoulder as measured by the vault model.

CONCLUSIONS

Patients with glenohumeral osteoarthritis do not appear to have abnormal premorbid glenoid retroversion or inclination. The glenoid vault model can be used to determine premorbid glenoid version and inclination.

CLINICAL RELEVANCE

The glenoid vault model may be a clinically useful tool to estimate patient-specific premorbid glenoid anatomy, which may help in preoperative or intraoperative surgical planning for total shoulder arthroplasty.

Addressing glenoid bone deficiency and asymmetric posterior erosion in shoulder arthroplasty

Glenoid bone deficiency and eccentric posterior wear are difficult problems faced by shoulder arthroplasty surgeons. Numerous options and techniques exist for addressing these issues. Hemiarthroplasty with concentric glenoid reaming may be a viable alternative in motivated patients in whom glenoid component failure is a concern. Total shoulder arthroplasty has been shown to provide durable pain relief and excellent function in patients, and numerous methods and techniques can assist in addressing bone loss and eccentric wear. However, the ideal amount of version correction in cases of severe retroversion has not yet been established. Asymmetric reaming is a commonly used technique to address glenoid version, but correction of severe retroversion may compromise bone stock and component fixation. Bone grafting is a technically demanding alternative for uncontained defects and has mixed clinical results. Specialized glenoid implants with posterior augmentation have been created to assist the surgeon in correcting glenoid version without compromising bone stock, but clinical data on these implants are still pending. Custom implants or instruments based on each patient's unique glenoid anatomy may hold promise. In elderly, sedentary patients in whom bone stock and soft-tissue balance are concerns, reverse total shoulder arthroplasty may be less technically demanding while still providing satisfactory pain relief and functional improvements.

Magnetic resonance scanning vs axillary radiography in the assessment of glenoid version for osteoarthritis

BACKGROUND

Osteoarthritic shoulders are mainly associated with glenoid retroversion. Total shoulder arthroplasty with the glenoid component implanted in retroversion predisposes to loosening of the glenoid prosthesis. Correction of glenoid retroversion through anterior eccentric reaming, before glenoid component implantation, is performed to restore normal joint biomechanics. Accurate preoperative assessment is required to ascertain the degree of retroversion and calculate the degree of reaming.

MATERIALS AND METHODS

We assessed the utility of magnetic resonance imaging (MRI) for the assessment of glenoid version in glenohumeral osteoarthritis compared with standard plain axillary radiography (AXR). Two independent observers reviewed both types of imaging in 48 primary osteoarthritic shoulders on 2 separate occasions.

RESULTS

The mean glenoid version measured was -14.3° on MRI and -21.6° on AXR (mean difference, -7.36°; P < .001). Intraobserver and interobserver reliability coefficients were 0.96 and 0.9, respectively, for MRI and 0.8 and 0.71, respectively, for AXR. Glenoid retroversion was greater in 73% of AXR.

CONCLUSION

We demonstrated that MRI is more reproducible in the assessment of glenoid version in osteoarthritis and provides excellent intraobserver and interobserver reliability. MRI is useful for preoperative osseous imaging for total shoulder arthroplasty because it offers a more precise method of determining glenoid version compared with x-ray imaging in addition to the standard assessment of rotator cuff integrity.

[Survival rate and complications of stemmed shoulder prostheses in primary osteoarthritis]

Survivorship and survival rate of shoulder prostheses can be affected by a large number of possible complications. An evaluation of the current literature and the prosthesis register, however, shows an overall low revision (1.39 revisions per 100 observation years) and loosening rates (implant-related 10-year survival rate up to 99%), comparable to that of hip and knee endoprostheses. It must be emphasized that cementless stems more often cause problems than cemented components (4.34 compared to 0.77 revisions per 100 observation years) and that secondary rotator cuff rupture (4.6%; functional deficit up to 30%) occurs more frequently than was generally assumed and is often not diagnosed or treated adequately. The infection rate amounts to approximately 1% and according to latest literature the dislocation rate is regressive and is estimated to be approximately 5%.The low complication and revision rates do not justify the replacement of stemmed prostheses by stemless implants and short stem prostheses and the preference given to the new implants is attributed more to the better revision possibilities and easier convertibility into inverse prostheses.

Conversion of shoulder arthroplasty to reverse implants: clinical and radiological results using a modular system

PURPOSE

Revision of a shoulder arthroplasty to a reverse arthroplasty is a highly demanding procedure. The aim of this study is to report the clinical results of hemi and total shoulder prosthesis revisions to reverse implants without removal of the humeral stem, using a modular shoulder replacement system (SMR Lima LTD). We retrospectively reviewed 26 patients who underwent an operation from 2004 to 2009.

METHODS

The patients were divided into two groups: in Group I, 18 patients underwent a revision of hemiarthroplasty implanted for fracture; in Group II, eight patients underwent a revision of anatomical total prosthesis. All patients were evaluated at a mean follow-up of 32.3 (±12.7) months using the Constant score rating scale and by range of motion evaluation, EQ-VAS, X-ray and CT scan.

RESULTS

The Constant score of each patient was 47.88 (±5.88) after the revision. The EQ-VAS improved from 40 (±20) to 70 (±10). All patients improved in terms of range of motion. The radiographs and CT scans obtained after revision showed good integration and no signs of loosening of the implant. The mean time of surgery was recorded as 62' (±8'), with a maximum blood loss of less than 300 ml in all cases.

CONCLUSIONS

Our study demonstrates that using a full modular system at the time of the first implant allows avoidance of the step to remove the humeral stem and metal back in cases of shoulder prosthesis revision to a reverse prosthesis, resulting in a short operative time, few intraoperative complications and a satisfactory clinical outcome at medium-term follow-up.

A biomechanical analysis of initial fixation options for porous-tantalum-backed glenoid components

BACKGROUND

Porous-tantalum (PT)-backed glenoid components have recently been developed to improve fixation and minimize the incidence of glenoid component loosening, which remains a key limiting factor in long-term survival in total shoulder arthroplasty. PT-backed glenoids promote bony ingrowth as a method of preventing glenoid loosening at the prosthesis-glenoid interface. The use of polymethyl-methacrylate (PMMA) cement for initial fixation may prevent osteointegration due to mechanical occlusion of the porous surface and the nonosteoconductive properties of PMMA. This study aims to investigate alternative fixation methods of PT-backed glenoids in a biomechanical investigation.

MATERIALS AND METHODS

Nine PT-backed monoblock glenoid components were implanted in a polyurethane bone substitute using either press-fit, PMMA cement, or calcium phosphate cement techniques. A control group of 3 all-polyethylene pegged glenoid components was implanted with PMMA. Glenoid and humeral head components were fixed to a biomechanical testing machine for testing according to ASTM Standard F-2028. The humeral head was translated ±1.5 mm along the superior-inferior axis for 50,000 cycles for characterization of glenoid rocking and inferior-superior translation.

RESULTS

Glenoid compression and glenoid distraction followed similar patterns for PT-backed glenoids. Overall, the all-polyethylene cemented glenoid demonstrated superior fixation compared to all PT-backed groups throughout the test. Glenoids fixed with PMMA cement displayed more favorable initial fixation and resistance to glenoid motion throughout cyclic testing.

CONCLUSION

This study showed that among PT-backed glenoids, PMMA fixation provided an increase in stability during initial and final cycles compared to press-fit and calcium-phosphate fixation techniques. This improved stability may enhance the osteointegration of the implant.

Incidence of early radiolucent lines after glenoid component insertion for total shoulder arthroplasty: a radiographic study comparing pressurized and unpressurized cementing techniques

BACKGROUND

Total shoulder arthroplasty (TSA) is commonly performed for arthritic conditions of the shoulder. The outcome after TSA is generally good, but there are several modes of failure, with one of the more common reasons being glenoid loosening. One possible cause for glenoid loosening is inadequate cementation technique. The purpose of this study was to evaluate the incidence of lucent lines on the first postoperative radiograph using 2 different cementation techniques.

MATERIALS AND METHODS

One hundred consecutive patients had a pegged glenoid placed with 1 of 2 different cementation techniques. In 26 consecutive patients, the pegged glenoid component was cemented with a traditional minimal manual pressurization technique, whereas 74 underwent a contemporary 3-step pressurization cementation technique before implant insertion. The first postoperative radiograph was evaluated using the system of Lazarus et al, looking at the frequency of lucent lines. The radiographs were deidentified and were randomized and evaluated by 2 independent observers on 3 separate occasions.

RESULTS

The Kruskal-Wallis test showed significant differences between grades of radiolucent lines for pressurized versus unpressurized cementation techniques. There were significantly (P < .05) fewer lucent lines identified in the group that underwent contemporary 3-step pressurization as opposed to the group that underwent minimal manual pressurization. Intraobserver reliability and interobserver reliability with Cronbach α coefficients were good.

CONCLUSION

The 3-step pressurized cementation technique resulted in a low incidence of radiolucent lines around the glenoid implant in patients undergoing TSA.

LEVEL OF EVIDENCE

Level II, Prospective Cohort, Treatment Study.

Intercellular adhesion molecule-1 (ICAM-1, CD54) is increased in adhesive capsulitis

BACKGROUND

The purpose of this study was to investigate the presence of intercellular adhesion molecule-1 (ICAM-1) in shoulders with adhesive capsulitis ("frozen shoulder").

METHODS

Glenohumeral capsular tissue was obtained from twenty-six patients (seventeen with adhesive capsulitis and nine controls), and ICAM-1 was evaluated with use of oligonucleotide arrays, real-time reverse transcription-polymerase chain reaction (RT-PCR), and immunohistochemistry. ICAM-1 was also evaluated in synovial fluid with use of western blotting (six patients with adhesive capsulitis and two controls) and in peripheral blood with use of an enzyme-linked immunosorbent assay (ELISA) (thirty-two patients with adhesive capsulitis, twenty with diabetes mellitus, and fourteen controls). The effect of ICAM-1 treatment on gene expression of cytokines related to inflammation and fibrosis was evaluated in cultured normal human synovial cells.

RESULTS

The level of ICAM-1 was significantly greater in capsular tissue from the glenohumeral joint of patients with adhesive capsulitis compared with controls as measured by oligonucleotide array analysis (0.12 ± 0.01 compared with 0.09 ± 0.00 arbitrary units) (p = 0.001), real-time RT-PCR (1.70 ± 0.19 compared with 0.67 ± 0.24 arbitrary units) (p < 0.05), and immunohistochemical staining. ICAM-1 was also significantly increased in the synovial fluid of patients with adhesive capsulitis (1.70 ± 0.18 arbitrary units) compared with normal controls (0.48 ± 0.17) (p < 0.05) and in serum of patients with adhesive capsulitis (633.22 ± 59.14 ng/mL) and patients with diabetes mellitus (671.25 ± 27.08 ng/mL) compared with controls (359.86 ± 44.29 ng/mL) (p < 0.05). Gene expression of cytokines related to inflammation and fibrosis in synoviocytes cultured in vitro was greater after three days of treatment with ICAM-1 and with ICAM-1 with glucose compared with untreated cells.

CONCLUSIONS

ICAM-1 was increased in patients with adhesive capsulitis, similar to the increase that has been reported in patients with diabetes mellitus.

Rates of radiolucency and loosening after total shoulder arthroplasty with pegged or keeled glenoid components

BACKGROUND

The objective of this study was to conduct a meta-analysis and cost-effectiveness analysis of the effect of glenoid design on radiolucency, loosening, and revision after total shoulder arthroplasty.

METHODS

We conducted a systematic review of PubMed, MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, and CINAHL with use of a search for the terms arthroplasty AND shoulder AND (peg OR keel). Data on study design and on the end points of radiolucency, loosening, and revision were extracted independently and in duplicate. Random-effect models were used to calculate the pooled risk ratio and risk difference. The risk difference was used to estimate the number needed to treat (the number of individuals who would have to receive a pegged component to avoid one loosening or revision).

RESULTS

Eight studies with a total of 1460 patients (mean age, sixty-seven years) were included. The mean study quality was 1.75 points (95% confidence interval [CI], 1.26 to 2.24) on the 3-point modified Jadad scale. There was no significant difference in the risk of any radiolucency (risk ratio, 0.42; 95% CI, 0.12 to 1.42) or in the risk of severe radiolucency (risk ratio, 0.65; 95% CI, 0.23 to 1.82) between pegged and keeled components. The pooled risk ratio for revision was 0.27 (95% CI, 0.08 to 0.88) in favor of pegged components (p = 0.028). At a cost-effectiveness threshold of $50,000 per quality-adjusted life year, pegged components can be between $2325 and $40,920 more expensive than keeled components and still be cost-effective.

CONCLUSIONS

Our study produced evidence that pegged glenoid components were associated with a lower revision risk compared with keeled components. However, the difference was rather small and will therefore be most meaningful to high-volume shoulder arthroplasty centers. Because of the similarity between primary and secondary costs, pegged glenoid designs were more cost-effective than keeled glenoid designs.

Humeral head arthroplasty and its ability to restore original humeral head geometry

BACKGROUND

Modern prosthetic components are designed to enable restoration of proximal humeral morphology, provided that a precise osteotomy of the humeral head at the level of the anatomic neck is performed. To determine whether a simulated osteotomy and replacement arthroplasty with an idealized implant were able to restore original head geometry.

MATERIALS AND METHODS

A handheld digitizer and surface laser scanner were used to digitize 24 humeri. Computer models were used to simulate an osteotomy, performed at the anterior cartilage-metaphyseal interface, and reconstruct the head with a spherical prosthetic head. The head diameter, radius of curvature, and inclination and retroversion angles were calculated for each specimen and compared with the original humeral head.

RESULTS

The simulated osteotomy resulted in a 4.8° decrease in inclination (P < .01) and 11.3° increase in retroversion (P < .001). The radius of curvature in the coronal plane was not significantly different (P = .284). However, in the axial plane, the prosthesis was significantly larger than the original head for both head diameter (P < .001) and radius of curvature (P < .05).

DISCUSSION

The study suggests that the humeral head is not a perfect segment of a sphere and an osteotomy along the anterior cartilage-metaphyseal interface does not remove only the proximal humeral articular surface. Even with a fully adaptable prosthetic implant, replacement arthroplasty is not able to restore original head geometry.

CONCLUSIONS

Alterations to head geometry with the osteotomy described may alter the line of force through the prosthetic joint, producing eccentric loading at the glenoid, and contribute to early failure.

Reverse shoulder arthroplasty in revision of failed shoulder arthroplasty-outcome and follow-up

PURPOSE

The number of shoulder arthroplasties has increased over the last decade, which can partly be explained by the increasing use of the reverse total shoulder arthroplasty technique. However, the options for revision surgery after primary arthroplasty are limited in cases of irreparable rotator cuff deficiency, and tuberosity malunion, nonunion, or resorption. Often, conversion to a reverse design is the only suitable solution. We analysed the functional outcome, complication rate and patient satisfaction after the revision of primary shoulder arthroplasty using an inverse design.

METHODS

Over a ten-year period 57 patients underwent revision surgery for failed primary shoulder arthroplasty using a reverse design. Of the 57 patients, 50 (mean age, 64.2 years) were available after an average follow-up of 51 months. Clinical evaluation included the Constant Murley Score, the UCLA score, and the Simple Shoulder Test, whereas radiological evaluation included plain radiographs in standard projections. Patients were also requested to rate their subjective satisfaction of the final outcome as excellent, good, satisfied or dissatisfied.

RESULTS

Compared to the preoperative status, the overall functional outcome measurements based on standardised outcome shoulder scores improved significantly at follow-up. The overall mean Constant Murley score improved from 18.5 to 49.3 points, the mean UCLA score improved from 7.1 to 21.6 points, and the mean simple shoulder test improved from 1.2 to 5.6 points. The average degree of abduction improved from 40 to 93° (p < 0.0001), and the average degree of anterior flexion improved from 47 to 98° (p < 0.0001). The median VAS pain score decreased from 7 to 1. Complications occurred in 12 cases (24 %).A total of 32 (64 %) patients rated their result as good or excellent, six (12 %) as satisfactory and 12 (24 %) as dissatisfied.

CONCLUSION

In revision shoulder arthroplasty after failed primary shoulder arthroplasty an inverse design can improve the functional outcome, and patient satisfaction is usually high. However, the complication rate of this procedure is also high, and patient selection and other treatment options should be carefully considered.

Results of anatomic nonconstrained prosthesis in primary osteoarthritis with biconcave glenoid

BACKGROUND

Biconcave glenoids in primary osteoarthritis represent a challenge because of the associated static posterior instability of the humeral head and secondary posterior glenoid erosion. This study evaluated the influence of different preoperative radiographic measurements on the outcome of total shoulder arthroplasty (TSA), particularly regarding the development of complications.

MATERIALS AND METHODS

We retrospectively evaluated 92 anatomic TSAs performed in 75 patients with primary osteoarthritis and a biconcave glenoid. All patients underwent preoperative imaging with an axial computed tomography arthrogram. Measurements were taken for posterior bone erosion depth and ratio as well as humeral head subluxation. Clinical outcomes were evaluated with the Constant score.

RESULTS

At an average follow up of 77 months (range, 14-180 months), 15 revisions (16.3%) were performed for glenoid loosening (6.5%), posterior instability (5.5%), or soft tissue problems (4.3%). At the final follow-up, the mean Constant score improved significantly from 32.4 to 68.8 points (P = .0001). Subjectively, 66.3% of patients were very satisfied or satisfied. Glenoid loosening was observed in 20.6% and was significantly associated with posterior bone erosion in depth (P = .005) and wear ratio (P = .02), humeral head subluxation (P = .01), and neoglenoid (P = .002) and intermediate glenoid retroversion (P = .001). Dislocation was correlated only with neoglenoid retroversion (P = .01).

CONCLUSIONS

Performing TSA in patients with osteoarthritis and biconcave glenoids resulted in acceptable clinical outcomes but a very high rate of complications. We found that the preoperative measurement of the neoglenoid retroversion was best for predicting postoperative complications in terms of glenoid loosening and dislocation.

Operative guidelines for the reconstruction of the native glenoid plane: an anatomic three-dimensional computed tomography-scan reconstruction study

BACKGROUND

Reconstruction of the native plane in biconcave eroded glenoids is difficult. Nevertheless, accurate reconstruction of this plane is imperative for successful total shoulder arthroplasty. This study aims to determine guidelines that can increase the accuracy of glenoid component positioning.

METHODS

Three different circular planes were determined on 3-dimensional computed tomography (CT) scans of 152 healthy shoulders. First, the circular max (CM) plane is formed with the superior tubercle and 2 points, 1 anterior and 1 posterior, at the rim of the inferior third of the glenoid. Second, the circular inferior (CI) plane is formed by 3 points at the inferior 2 quadrants of the glenoid rim. Third, the circular minima (Cm) plane is formed with 3 points situated at the noneroded sector of the anterior glenoid. The angulation of the spinal scapular axis (SSA), the line between the most medial point of the scapular spine and the center of the three different glenoid planes, and the correlation coefficient between the radius of the circle and the length of SSA are calculated.

RESULTS

Angle SSA in the x-axis were 94°, 93°, 93° and in the y-axis were 95°, 111°, and 111° for CM, CI, and Cm, respectively. Correlation coefficient between the radius of the circle and the length of SSA: r = 0.69 for CM, r = 0.75 for CI, and r = 0.75 for Cm.

CONCLUSION

Three points situated at the native anterior glenoid can reconstruct, within 2° accuracy (95% confidence interval, 1.8°-2.3°), the CI plane. A relationship exists between the radii of the 3 glenoid circles and the width of the scapula (SSA length).

Total shoulder arthroplasty does not correct the orientation of the eroded glenoid

BACKGROUND AND PURPOSE

Alignment of the glenoid component with the scapula during total shoulder arthroplasty (TSA) is challenging due to glenoid erosion and lack of both bone stock and guiding landmarks. We determined the extent to which the implant position is governed by the preoperative erosion of the glenoid. Also, we investigated whether excessive erosion of the glenoid is associated with perforation of the glenoid vault.

METHODS

We used preoperative and postoperative CT scans of 29 TSAs to assess version, inclination, rotation, and offset of the glenoid relative to the scapula plane. The position of the implant keel within the glenoid vault was classified into three types: centrally positioned, component touching vault cortex, and perforation of the cortex.

RESULTS

Preoperative glenoid erosion was statistically significantly linked to the postoperative placement of the implant regarding all position parameters. Retroversion of the eroded glenoid was on average 10° (SD10) and retroversion of the implant after surgery was 7° (SD11). The implant keel was centered within the vault in 7 of 29 patients and the glenoid vault was perforated in 5 patients. Anterior cortex perforation was most frequent and was associated with severe preoperative posterior erosion, causing implant retroversion.

INTERPRETATION

The position of the glenoid component reflected the preoperative erosion and "correction" was not a characteristic of the reconstructive surgery. Severe erosion appears to be linked to vault perforation. If malalignment and perforation are associated with loosening, our results suggest reorientation of the implant relative to the eroded surface.

A three-dimensional analysis of humeral head retroversion

INTRODUCTION

The anatomic neck of the humerus is used as a reference for the osteotomy in shoulder arthroplasty. Resection along the anterior portion of the cartilage/metaphyseal border is assumed to remove a cap of a sphere that can accurately be replaced with a spherical prosthetic implant oriented precisely to the original articular surface. The aim of this study was to determine the variability in retroversion of the cartilage/metaphyseal interface in the axial plane.

METHODS

Surface topography data for 24 arms from deceased donors were collected by using a hand-held digitizer and a surface laser scanner. Data were combined into the same coordinate system and graphically presented. The humeral head was divided into 6 sections in the axial plane and the retroversion angle measured at each level with reference to the transepicondylar axis at the elbow.

RESULTS

The mean retroversion of the humeral head at the midpoint between the superior and inferior margins was 18.6°. The angle increased as the position of the measurement moved superiorly to 22.5°. In contrast, the retroversion angle reduced as the position of measurement moved more inferiorly to 14.3°.

DISCUSSION

The results suggest that the cartilage/metaphyseal interface is not circular encompassing a spherical cap of a sphere. Furthermore, there appears to be a clockwise torsion of the cartilage/metaphyseal interface about the transverse axis from its medial to lateral aspect.

CONCLUSION

The cartilage/metaphyseal interface shows a degree of variability that makes it an unreliable landmark to perform an osteotomy when the anterior aspect of the interface is used.

Humeral component revision arthroplasty: outcomes of a split osteotomy technique

BACKGROUND

The purpose of our study was to report results on 13 patients who underwent shoulder revision surgery of a well-fixed cemented humeral component assisted by a longitudinal split osteotomy. Limited data have been published on humeral stem revision using an osteotomy to facilitate removal of a well-fixed humeral component.

MATERIALS AND METHODS

Between July 1996 and July 2004, 13 humeral component revisions of well-fixed cemented stems were performed for pain and functional limitation. The patients' preoperative and postoperative function and outcome were evaluated by physical examination, visual analog scale (VAS) for pain, Simple Shoulder Test (SST), American Shoulder and Elbow Surgeons (ASES) score, Short Form-12 (SF-12), and radiographic assessment.

RESULTS

At a mean follow-up of 30 months, from preoperatively to postoperatively, the VAS pain score improved from 7.8 to 2.3 (P = .012), the ASES score improved from 19.6 to 58.9 (P < .011), the SST score improved from 1.4 to 4.6 (P < .011), and significant changes were demonstrated on the mental component of the SF-12, with improvement from 49.8 to 59.4 (P < .025). Analysis of range of motion from preoperatively to postoperatively revealed that the mean external rotation improved from 24.4° to 40° (P < .042), and mean forward elevation improved from 60.6° to 89.4°, although this change was not significant (P = .067). There were no iatrogenic fractures. Radiographic follow-up demonstrated no evidence of humeral loosening or nonunion.

CONCLUSIONS

A longitudinal humeral split osteotomy is a safe and effective technique for revision of a well-fixed humeral stem.

Postoperative pain associated with orthopedic shoulder and elbow surgery: a prospective study

BACKGROUND

In the last 2 decades, extensive research in postoperative pain management has been undertaken to decrease morbidity. Orthopedic procedures tend to have increased pain compared with other procedures, but further research must be done to manage pain more efficiently. Postoperative pain morbidities and analgesic dependence continue to adversely affect health care.

MATERIALS AND METHODS

The study assessed the pain of 78 elbow and shoulder surgery patients preoperatively and postoperatively using the Short-Form McGill Pain Questionnaire (SF-MPQ). Preoperatively, each patient scored their preoperative pain (PP) and anticipated postoperative pain (APP). Postoperatively, they scored their 3-day (3dpp) and 6-week postoperative pain (6wpp). The pain intensities at these 4 intervals were then compared and analyzed using Pearson coefficients.

RESULTS

APP and PP were strong predictors of postoperative pain. The average APP was higher than the average postoperative pain. The 6wpp was significantly lower than the 3dpp. Sex, chronicity, and type of surgery were not significant factors; however, the group aged 18 to 39 years had a significant correlation with postoperative pain.

CONCLUSION

PP and APP were both independent predictors of increased postoperative pain. PP was also predictive of APP. Although, overall postoperative pain was lower than APP or PP due to pain management techniques, postoperative pain was still significantly higher in patients with increased APP or PP than their counterparts. Therefore, surgeons should factor patient's APP and PP to better manage their patient's postoperative pain to decrease comorbidities.

Mechanical characteristics of a novel posterior-step prosthesis for biconcave glenoid defects

BACKGROUND

Posterior glenoid defects increase the risk of glenoid component loosening after total shoulder arthroplasty (TSA). The goal of this work was to evaluate the mechanical performance of a novel posterior-step glenoid prosthesis, designed to compensate for biconcave (type B2) glenoid defects. Two prototypes ("Poly-step" and "Ti-step") were constructed by attaching polyethylene or titanium step-blocks onto standard (STD) glenoid prostheses. We hypothesized that the mechanical performance of the experimental prostheses in the presence of a B2 defect would be similar to that of an STD prosthesis in the absence of a defect.

METHODS

Fifteen normal shoulder specimens were consistently loaded under simulated muscle activity while peri-glenoid bone strains were measured. In 5 specimens, arthroplasty was performed with an STD glenoid prosthesis. In the remaining 10 specimens, a 20° B2 glenoid defect was created before arthroplasty was performed with the Poly-step or Ti-step prosthesis.

RESULTS

Load-induced peri-glenoid strains after TSA with either the STD or Poly-step prosthesis did not show statistical differences as compared with the native joints (P > .05). A posterior defect decreased superior glenoid strain as compared with the intact specimens (P < .05). The change in strains after Poly-step prosthesis implantation in the presence of a biconcave glenoid defect was not different than the change induced by STD prosthesis implantation in the absence of a defect. In contrast, strains after Ti-step prosthesis implantation were statistically different from those induced by the STD and Poly-step prostheses (P < .05).

CONCLUSIONS

The Poly-step prosthesis may be a viable option for treating posterior glenoid defects.

Effect of glenoid deformity on glenoid component placement in primary shoulder arthroplasty

BACKGROUND

Malposition of the glenoid component can result in premature component loosening or instability. This study was designed to test the ability of an experienced shoulder surgeon to position the glenoid component using standard preoperative planning and surgical bone preparation.

MATERIALS AND METHODS

Thirteen patients having primary total shoulder arthroplasty were evaluated using 3-dimensional surgical simulator. Ideal version was considered to have version as close to perpendicular to the plane of the scapula, with complete contact of the back side of the component on glenoid bone and maintenance of the center peg of the component within bone.

RESULTS

The average retroversion angle was 13° (mean, standard deviation [SD] 12°), with a range of 1-42°. In 7 of these 13 cases, preoperative glenoid retroversion was greater or equal to 10°. In 3 cases, the component was malpositioned with greater than 10° of ideal version. In cases with less than 10° of preoperative retroversion, the glenoid component was placed within 10° of ideal version in all cases.

CONCLUSION

Traditional methods to correct moderate to severe glenoid deformity and place the glenoid component within 5° of the ideal position are not consistent. Optimal glenoid component placement can be achieved when there is minimal bone deformity. Retroversion greater or equal to 20° makes it difficult to place a pegged glenoid component perpendicular to the plane of the scapula by asymmetric reaming without center peg perforation.

The vertical humeral osteotomy for stem removal in revision shoulder arthroplasty: results and technique

HYPOTHESIS

Revision shoulder arthroplasty represents a complex and difficult problem for the treating surgeon, with multiple potential complications. In the setting of a well-fixed humeral component, removal can lead to fractures and compromise the outcome of the revision. The current study describes and evaluates the results of a novel vertical humeral osteotomy (VHO) for stem extraction. We hypothesized that the VHO will enable successful stem extraction without perioperative or postoperative fractures.

MATERIALS AND METHODS

Twenty-seven patients were retrospectively identified who had a VHO for revision shoulder arthroplasty, with 23 patients available for final follow-up. Records and radiographs were reviewed for postoperative complications. Final follow-up was completed with the inclusion of shoulder scores.

RESULTS

There were no perioperative or postoperative fractures on clinical examination and radiographic review at an average follow-up of 41 months. Average American Shoulder and Elbow Surgeons (ASES) score was 64.7 (contralateral ASES, 76.9), average Simple Shoulder Test was 6.3, and the visual analog score pain average was 1.3. There were no instability events.

DISCUSSION

The glenoid is the more common site for failure in both hemiarthroplasty and total shoulder arthroplasty. This can lead to a difficult revision procedure if the ingrown or cemented humeral stem requires removal.

CONCLUSION

In the current study, we found the VHO was an effective tool for the removal of the humeral prosthesis with no perioperative or postoperative fractures.

The glenoid in total shoulder arthroplasty

Management of glenohumeral arthrosis with a total shoulder prosthesis is becoming increasingly common. However, failure of the glenoid component remains one of the most common causes for failure. Our understanding of this problem has evolved greatly since the first implants were placed in the 1970's. However glenoid failure remains a challenging problem to address and manage. This article reviews the current knowledge regarding the glenoid in total shoulder arthroplasty touching on anatomy, component design, implant fixation, causes of implant failure, management of glenoid failure and alternatives to glenoid replacement.

Review of fixation techniques for the four-part fractured proximal humerus in hemiarthroplasty

Introduction

The clinical outcome of hemiarthroplasty for proximal humeral fractures is not satisfactory. Secondary fragment dislocation may prevent bone integration; the primary stability by a fixation technique is therefore needed to accomplish tuberosity healing. Present technical comparison of surgical fixation techniques reveals the state-of-the-art approach and highlights promising techniques for enhanced stability.

Method

A classification of available fixation techniques for three- and four part fractures was done. The placement of sutures and cables was described on the basis of anatomical landmarks such as the rotator cuff tendon insertions, the bicipital groove and the surgical neck. Groups with similar properties were categorized.

Results

Materials used for fragment fixation include heavy braided sutures and/or metallic cables, which are passed through drilling holes in the bone fragments. The classification resulted in four distinct groups: A: both tuberosities and shaft are fixed together by one suture, B: single tuberosities are independently connected to the shaft and among each other, C: metallic cables are used in addition to the sutures and D: the fragments are connected by short stitches, close to the fragment borderlines.

Conclusions

A plurality of techniques for the reconstruction of a fractured proximal humerus is found. The categorisation into similar strategies provides a broad overview of present techniques and supports a further development of optimized techniques. Prospective studies are necessary to correlate the technique with the clinical outcome.

Long-term results and patient satisfaction after shoulder resurfacing

BACKGROUND

Shoulder resurfacing has regained popularity in recent years. This report presents the long-term (>20 years) results of this procedure with regard to patient satisfaction and implant survival.

MATERIALS AND METHODS

We followed up 61 patients who underwent shoulder resurfacing procedures (74 shoulders) for a minimum of 20 years or until death (7 additional patients were lost to follow-up). The mean patient age at the time of surgery was 58 years. There were 41 total resurfacing procedures and 33 hemi-resurfacing procedures. The humeral component consisted of a cup with a short central peg that was placed either with or without cement. The glenoid was resurfaced with a cemented polyethylene or polyurethane component.

RESULTS

Patient satisfaction was 95%, and the survivorship of the humeral prostheses was 96%. There were no periprosthetic fractures, dislocations, or infections. Two humeral components were revised to stemmed prostheses (one for loosening and one for unexplained pain), and one was revised from a cementless to a cemented resurfacing prosthesis. Twelve cemented polyethylene glenoid prostheses had radiolucencies, but only three produced symptoms requiring revision surgery; three polyurethane glenoid prostheses showed severe wear radiographically, but none was loose or required revision surgery. There were 7 revision procedures, 6 with good results.

CONCLUSIONS

Shoulder resurfacing is a successful procedure for the majority of patients, with high rates of patient satisfaction, long-term survivorship of the humeral prosthesis, and few complications.

Position of shoulder arthroplasty and clinical outcome in proximal humerus fractures

Four-part proximal humeral fractures are frequently treated with shoulder replacement. Outcome of this procedure has not been standardized, and there are controversy data on range of motion (ROM) and active function of the shoulder. The aim of this study is to compare shoulder prosthesis position (SPP) in terms of version of humeral head and height of stem with clinical subjective and objective outcome. Fifty patients were treated with shoulder hemiarthroplasty for four-part proximal humeral fracture or fracture-dislocation of the humeral head. Radiological examination and CT-scan were performed preoperatively and at follow-up. Clinical outcome evaluation included active and passive ROM, and subjective perspective collected through SF-36, OSQ, ASES, and DASH. No significant correlation between stem height and clinical outcome were found. The prosthesis version correlates with all subjective questionnaires. The ROM was not correlated with stem height and prosthesis version. SPP involves clinical outcome, with great relevance of implant version.

Comparison of standard two-dimensional and three-dimensional corrected glenoid version measurements

HYPOTHESIS

There is concern regarding the accuracy of 2-dimensional (2D) computed tomography (CT) for measuring glenoid version. Three-dimensional (3D) CT scan reconstructions can properly orient the glenoid to the plane of the scapula and have been reported to accurately measure glenoid version in cadaver models. We hypothesized that glenoid version measured by correcting 2D CT scans to the plane of the scapula by 3D reconstruction would be significantly different compared with standard 2D CT scan measurement of the glenoid in a clinical patient population.

MATERIALS AND METHODS

Thirty-four patients underwent dedicated axial 2D CT scan of the shoulder with 3D reconstruction. The 2D glenoid version was measured on unmodified midglenoid axial cuts, and the 3D glenoid version measurement was corrected to be perpendicular to the plane of the scapula and then measured in the axial plane. Three observers repeated each measurement on 2 different days.

RESULTS

The difference between the overall average 2D and 3D measurements was not statistically significant (P = .45). In individual scapulae, 35% of 2D measurements were 5° to 10° different and 12% were greater than 10° different from their corresponding 3D-corrected CT measurement (P < .001 to P = .045). Reproducibility of both 2D and 3D-corrected measurements was good.

DISCUSSION

Although 2D and 3D corrected methods showed a high degree of both intraobserver and interobserver reliability in this series, axial 2D images without correction were 5 to 15 degrees different than their 3D-corrected counterparts in 47% of all measurements. Correcting 2D glenoid version by 3D reconstruction to the transverse plane perpendicular to the scapular body allows for an accurate assessment of glenoid version in spite of positioning differences and results in increased accuracy while maintaining high reliability.

CONCLUSIONS

Owing to the variability in scapular position, the axial 2D CT scan measurement was significantly different from 3D-corrected measurement of glenoid version. Averaging the version measurements across patients did not reflect this finding.

Reverse shoulder prosthesis for acute four-part fracture: tuberosity fixation using a horseshoe graft

Results of hemiarthroplasty for complex four-part proximal humerus fractures in the elderly have been unreliable. Although patients often achieve pain relief, return of above-shoulder level function can be challenging, because tuberosity nonunion, malunion, and/or resorption is quite common. The reverse shoulder replacement has been advocated as a reliable alternative for these patients. Preliminary studies have suggested that tuberosity healing is critical for achieving external rotation strength after reverse shoulder arthroplasty. We describe a technique of tuberosity repair using a wedge horseshoe graft, which can provide improved surface area for tuberosity healing. A clinical series of seven patients treated with this technique is reported with a minimum follow-up of 12 months (range, 12-23 months). The tuberosity union rate was 86% (six of seven patients). Average active forward elevation was 117° (range, 95°-150°), and active external rotation was 19° (range 0°-30°). Visual analog scale pain scores averaged 0.6 (range, 0-1), visual analog scale function averaged 8.7 (range, 7-10), mean American Shoulder and Elbow Surgeons pain was 47.1 (range, 45-50), and mean American Shoulder and Elbow Surgeons function was 39.2 (range, 31-50). Subjective satisfaction ratings were excellent for four patients, and good for two, and satisfactory for one. No patients were unsatisfied with their outcomes. The horseshoe graft technique provides a reliable means for anatomic restoration of the tuberosities, facilitating the return of shoulder function in elderly patients with complex four-part proximal humerus fractures treated with a reverse total shoulder.

A quantitative method for determining medial migration of the humeral head after shoulder arthroplasty: preliminary results in assessing glenoid wear at a minimum of two years after hemiarthroplasty with concentric glenoid reaming

HYPOTHESIS

Glenoid erosion and medial migration of the humeral head prosthesis have been observed after most types of shoulder arthroplasty. A method of measuring the change in humeral head position with time after shoulder prosthetic arthroplasty was applied it to 14 shoulders that underwent humeral hemiarthroplasty with concentric glenoid reaming. We hypothesized that the measurement technique would be reproducible and that the rate of wear would be small in the series of shoulders studied.

MATERIALS AND METHODS

Standardized anteroposterior and axillary radiographs were obtained after surgery. Two examiners measured the position of the humeral head center in relation to scapular reference coordinates for the anteroposterior and axillary projections and plotted these values against time after surgery. The change in position was characterized as the slope of this plot. Shoulders were included if there were at least 3 sets of postoperative films, the last being at least 2 years after surgery.

RESULTS

The slopes measured by the 2 examiners agreed within 0.5 mm/y for the anteroposterior and the axillary projections. For the series of shoulder arthroplasties, the rate of movement of the head center toward the scapula was less than 0.4 mm/y for either examiner in either projection.

DISCUSSION

Medial migration is a concern after any type of shoulder arthroplasty, whether a hemiarthroplasty, a biological interpositional arthroplasty, or a total shoulder arthroplasty. Quantifying the rate of medial migration over time after shoulder arthroplasty is an important element of clinical follow-up.

CONCLUSIONS

This is an inexpensive, practical, and reproducible method that can be used to determine the rate of medial migration of the humeral head on plain radiographs after shoulder arthroplasty. The average rate of medial migration in the shoulders in this study was small.

Predicting normal glenoid version from the pathologic scapula: a comparison of 4 methods in 2- and 3-dimensional models

BACKGROUND

Correction of pathologic glenoid retroversion improves gleonhumeral mechanics and reduces glenoid component wear after total shoulder arthroplasty. Determining the amount of correction necessary can be difficult because of the wide range of normal glenoid version. We hypothesize that normal glenoid version can be predicted in a pathologic shoulder based on conserved relationships between the anterior glenoid wall, Resch angle, and the internal structures of the glenoid vault.

MATERIALS AND METHODS

Three-dimensional (3-D) computer tomography (CT) scan-based measurements of the anterior glenoid wall angle (AGWA), Resch angle (RA), and glenoid version were made in 58 scapulae from the Haeman-Todd Osteological Collection (Museum of Natural History in Cleveland, OH) and 19 paired scapulae from patients with unilateral osteoarthritis. Linear regression equations derived from the AGWA and RA and from a computer-generated vault model were used to predict native (nonpathologic) glenoid version as defined by the 19 nonpathologic scapula.

RESULTS

Linear regression equations based on the measured AGWA or RA, as well as the glenoid vault model in the 19 pathologic scapulae, were able to accurately predict native glenoid version in the contralateral nonpathologic shoulder.

DISCUSSION

This study demonstrates the ability to take 3-D CT scan-based measurements in a scapula with pathologic glenoid retroversion and predict the native (nonpathologic) glenoid version in the contralateral shoulder by using linear regression equations or a computer generated vault model. Such tools might assist in preoperative planning and intraoperative decision making to allow correction of pathologic glenoid retroversion.