Non-Labeled, Stable Labeled, or Radiolabelled Approaches for Provision of Intravenous Pharmacokinetics in Humans: A Discussion Piece

A review of the use of microdoses and isotopic microtracers for clinical intravenous pharmacokinetic (i.v. PK) data provision is presented. The extent of application of the varied approaches available and the relative merits of each are highlighted with the aim of assisting practitioners in making informed decisions on the most scientifically appropriate design to adopt for any given new drug in development. It is envisaged that significant efficiencies will be realized as i.v. PK data in humans becomes more routinely available for suitable assets in early development, than has been the case prior to the last decade.

Metabolite Bioanalysis in Drug Development: Recommendations from the IQ Consortium Metabolite Bioanalysis Working Group

The intent of this perspective is to share the recommendations of the International Consortium for Innovation and Quality in Pharmaceutical Development Metabolite Bioanalysis Working Group on the fit-for-purpose metabolite bioanalysis in support of drug development and registration. This report summarizes the considerations for the trigger, timing, and rigor of bioanalysis in the various assessments to address unique challenges due to metabolites, with respect to efficacy and safety, which may arise during drug development from investigational new drug (IND) enabling studies, and phase I, phase II, and phase III clinical trials to regulatory submission. The recommended approaches ensure that important drug metabolites are identified in a timely manner and properly characterized for efficient drug development.

Recommendations on the Use of Multiple Labels in Human Mass Balance Studies

The administration of radiolabeled drug candidates is considered the gold standard in absorption, distribution, metabolism, and excretion studies for small-molecule drugs since it allows facile and accurate quantification of parent drug, metabolites, and total drug-related material independent of the compound structure. The choice of the position of the radiolabel, typically 14C or 3H, is critical to obtain relevant information. Sometimes, a biotransformation reaction may lead to cleavage of a part of the molecule. As a result, only the radiolabeled portion can be followed, and information on the fate of the nonlabeled metabolite may be lost. Synthesis and administration of two or more radiolabeled versions of the parent drug as a mixture or in separate studies may resolve this issue but comes with additional challenges. In this paper, we address the questions that may be considered to help make the right choice whether to use a single or multiple radiolabel approach and discuss the pros and cons of different multiple-labeling strategies that can be taken as well as alternative methods that allow the nonlabeled part of the molecule to be followed. SIGNIFICANCE STATEMENT: Radiolabeled studies are the gold standard in drug metabolism research, but molecules can undergo cleavage with loss of the label. This often results in discussions around potential use of multiple labels, which seem to be occurring with increased frequency since an increasing proportion of the small-molecule drugs are tending towards larger molecular weights. This review provides insight and decision criteria in considering a multiple-label approach as well as pros and cons of different strategies that can be followed.

Evaluation of the drug disposition of RO7049389 with in vitro data and human mass balance supported by physiologically based pharmacokinetic modelling

AIMS

RO7049389 (linvencorvir) is a developmental oral treatment for chronic hepatitis B virus infection. The aim of this work was to conduct mass balance (MB) and absolute bioavailability (BA) analyses in healthy volunteers, alongside in vitro evaluations of the metabolism of RO7049389 and a major circulating active metabolite M5 in human hepatocytes, and physiologically based pharmacokinetic (PBPK) modelling to refine the underlying drug disposition paradigm.

METHODS

Participants in the clinical study (MB: Caucasian, male, n = 6; BA: Caucasian and Asian, male and female, n = 16, 8 in each ethnic groups) received oral [14 C] or unlabelled RO7049389 (600/1000 mg) followed by 100 μg intravenous [13 C]RO7049389. Metabolic pathways with fractions metabolized-obtained from the in vitro incubation results of 10 μM [14 C]RO7049389 and 1 μM M5 with (long-term cocultured) human hepatocytes in the absence and presence of the cytochrome P450 3A4 (CYP3A4) inhibitor itraconazole-were used to complement the PBPK models, alongside the clinical MB and BA data.

RESULTS

The model performance in predicting the pharmacokinetic profiles of RO7049389 and M5 aligned with clinical observations in Caucasians and was also successfully applied to Asians. Accordingly, the drug disposition pathways for RO7049389 were postulated with newly characterized estimates of the fractions: biliary excretion by P-glycoprotein (~41%), direct glucuronidation via uridine 5'-diphosphoglucuronosyltransferase 1A3 (~11%), hexose conjugation (~6%), oxidation by CYP3A4 (~28%) and other oxidation reactions (~9%).

CONCLUSION

These results support the ongoing clinical development program for RO7049389 and highlight the broader value of PBPK and MB analyses in drug development.

Absorption, distribution, metabolism, and excretion of [14C]iptacopan in healthy male volunteers and in in vivo and in vitro studies

Iptacopan (LNP023) is an oral, small-molecule, first-in-class, highly potent proximal complement inhibitor that specifically binds factor B and inhibits the alternative complement pathway. Iptacopan is currently in development as a targeted treatment for PNH and multiple other complement-mediated diseases. In this study, the absorption, distribution, metabolism, and excretion (ADME) of iptacopan was characterized in six healthy volunteers after a single 100 mg oral dose of [¹⁴C]iptacopan. This was supplemented with an in vivo rat ADME study and metabolite exposure comparisons between human, rat and dog, in addition to in vitro assays, to better understand the clearance pathways and enzymes involved in the metabolism of iptacopan. The fraction of [¹⁴C]iptacopan absorbed was estimated to be about 71%, with a time to maximum concentration (T_max) of 1.5 h and elimination half-life from plasma of 12.3 h. Following a single dose of [¹⁴C]iptacopan, 71.5% of the radioactivity was recovered in feces and 24.8% in urine. [¹⁴C]iptacopan was primarily eliminated by hepatic metabolism. The main biotransformation pathways were oxidative metabolism via CYP2C8, with M2 being the major oxidative metabolite, and acyl glucuronidation via UGT1A1. The two acyl glucuronide metabolites in human plasma, M8 and M9, each accounted for {less than or equal to}10% of the total circulating drug-related material; systemic exposure was also observed in toxicology studies in rat and dog, suggesting a low risk associated with these metabolites. Binding of iptacopan to its target, factor B, in the bloodstream led to a concentration-dependent blood:plasma distribution and plasma protein binding of [¹⁴C]iptacopan. Significance Statement We characterized the pharmacokinetics, excretion, metabolism and elimination of [¹⁴C]iptacopan (an oral, selective small-molecule inhibitor of factor B) - in healthy human subjects. [¹⁴C]iptacopan was primarily eliminated by metabolism. The primary biotransformation pathways were oxidative metabolism via CYP2C8 and acyl glucuronidation via UGT1A1. Direct secretion of iptacopan into urine and potentially bile represented additional elimination mechanisms. Binding of iptacopan to its target, factor B, in the bloodstream led to a concentration-dependent blood:plasma distribution and plasma protein binding of [¹⁴C]iptacopan.

Considerations for Human ADME Strategy and Design Paradigm Shift(s) - An Industry White Paper

The human absorption, distribution, metabolism, and excretion (hADME) study is the cornerstone of the clinical pharmacology package for small molecule drugs, providing comprehensive information on the rates and routes of disposition and elimination of drug-related material in humans through the use of 14 C-labeled drug. Significant changes have already been made in the design of the hADME study for many companies, but opportunity exists to continue to re-think both the design and timing of the hADME study in light of the potential offered by newer technologies, that enable flexibility in particular to reducing the magnitude of the radioactive dose used. This paper provides considerations on the variety of current strategies that exist across a number of pharmaceutical companies and on some of the ongoing debates around a potential move to the so called "human first/human only" approach, already adopted by at least one company. The paper also provides a framework for continuing the discussion in the application of further shifts in the paradigm.

Exploration and application of a liver-on-a-chip device in combination with modelling and simulation for quantitative drug metabolism studies

Microphysiological systems (MPS) are complex and more physiologically realistic cellular in vitro tools that aim to provide more relevant human in vitro data for quantitative prediction of clinical pharmacokinetics while also reducing the need for animal testing. The PhysioMimix liver-on-a-chip integrates medium flow with hepatocyte culture and has the potential to be adopted for in vitro studies investigating the hepatic disposition characteristics of drug candidates. The current study focusses on liver-on-a-chip system exploration for multiple drug metabolism applications. Characterization of cytochrome P450 (CYP), UDP-glucuronosyl transferase (UGT) and aldehyde oxidase (AO) activities was performed using 15 drugs and in vitro to in vivo extrapolation (IVIVE) was assessed for 12 of them. Next, the utility of the liver-on-a-chip for estimation of the fraction metabolized (f_m) via specific biotransformation pathways of quinidine and diclofenac was established. Finally, the metabolite identification opportunities were also explored using efavirenz as an example drug with complex primary and secondary metabolism involving a combination of CYP, UGT and sulfotransferase enzymes. A key aspect of these investigations was the application of mathematical modelling for improved parameter calculation. Such approaches will be required for quantitative assessment of metabolism and/or transporter processes in systems where medium flow and system compartments result in non-homogeneous drug concentrations. In particular, modelling was used to explore the effect of evaporation from the medium and it was found that the intrinsic clearance (CL_int) might be underestimated by up to 40% for low clearance compounds if evaporation is not accounted for. Modelling of liver-on-a-chip in vitro data also enhanced the approach to f_m estimation allowing objective assessment of metabolism models of different complexity. The resultant diclofenac f_m,UGT of 0.64 was highly comparable with values reported previously in the literature. The current study demonstrates the integration of mathematical modelling with experimental liver-on-a-chip studies and illustrates how this approach supports generation of high quality of data from complex in vitro cellular systems.

Arthroscopic soft tissue reconstruction in anterior shoulder instability

Anterior glenohumeral instability remains a difficult problem in the athletic and working patient populations. Treatment strategies are variable and range from nonoperative approaches incorporating immobilization and rehabilitation to surgical management. Surgical decision-making can be challenging, especially with a high-level patient who wishes to return to high-demand activities. Operative options range from open soft tissue stabilization to arthroscopic soft tissue stabilization, with both open and arthroscopic options for bony reconstruction in the setting of clinically significant anterior glenoid bone loss. In all cases, understanding appropriate indications and utilizing sound surgical techniques are critical for achieving a successful result. For the majority of patients with anterior shoulder instability, arthroscopic soft tissue reconstruction with suture anchors is a successful, minimally invasive approach that results in a stable shoulder with excellent outcomes and low complication rates.

Comparative outcomes of outpatient and inpatient total shoulder arthroplasty: an analysis of the Medicare dataset

AIMS

The aim of the present study was to compare the 30- and 90-day re-admission rates and complication rates of outpatient and inpatient total shoulder arthroplasty (TSA).

PATIENTS AND METHODS

The United States Medicare Standard Analytical Files database was questioned to identify patients who had undergone outpatient or inpatient TSA between 2005 and 2012. Patient characteristics were compared between the two groups using chi-squared analysis. Multivariate logistic regression analysis was used to control for differences in baseline patient characteristics and to compare the two groups in terms of post-operative complications within 90 days and re-admission within 30 days and 90 days.

RESULTS

A total of 123 347 Medicare subscribers underwent TSA between 2005 and 2012; 3493 (2.8%) had the procedure performed as an outpatient. A significantly greater proportion of patients who underwent TSA as inpatients were women, had a history of smoking, and had a greater incidence of medical comorbidity including diabetes, coronary artery disease, congestive heart failure, and chronic kidney disease (p < 0.05 for all). Re-admission rates were significantly higher for inpatients at both 30 days (0.83% versus 0.60%, p = 0.016, odds ratio 1.8) and 90 days (2.87% versus 2.04%, p < 0.001, odds ratio 1.8). Complications, including thromboembolic events (p < 0.001) and surgical site infection (p = 0.002), were significantly higher in inpatients.

CONCLUSION

Patients who underwent TSA on an outpatient basis were overall younger and healthier than those who had inpatient surgery, which suggests that patient selection was taking place. After controlling for age, gender, and medical conditions, patients who underwent TSA as outpatients had lower rates of 30- and 90-day re-admission and a lower rate of complications than inpatients. Cite this article: Bone Joint J 2017;99-B:934-8.

Biomechanical testing of the reconstructed ulnar collateral ligament: a systematic review of the literature

PURPOSE

The purpose was to perform a systematic review of the literature investigating biomechanical studies of ulnar collateral ligament reconstruction (UCLR) techniques to summarize the most commonly analyzed methods of fixation (at both the ulna and humerus), the degree of elbow flexion at the time of fixation, graft characteristics, and modes of failure with these techniques.

MATERIALS AND METHODS

A systematic review was performed. All cadaveric biomechanical studies that tested a reconstruction method for UCLR were included. Descriptive statistics were calculated for each study and parameter/variable analyzed.

RESULTS

Twenty-three studies were included with a total of 397 elbows in 242 cadavers (mean age 54.8 ± 20 years, range 16-96). The majority of studies (65 %) used a palmaris longus graft. The docking technique (37.2 %) was the most commonly tested reconstruction method. Significant heterogeneity between studies precluded assimilation of specific techniques (each of the 23 studies utilized a unique technique). Fixation was performed at 30°-90° of elbow flexion. The most common mode of failure was suture failure (51 %), followed by midsubstance rupture (27.00 %), and bone tunnel fracture (14.00 %). No significant differences were observed amongst techniques for all measures analyzed.

CONCLUSION

This study found the docking technique to be the most commonly tested technique, while the mode of reconstruction failure was most commonly at the suture interface. If the graft failed at the bone interface, it was most likely to occur at the ulna. Surgeon preference and comfort level with a specific technique should dictate choice.

Clinical outcomes of revision biceps tenodesis

Purpose:

Biceps tenotomy and tenodesis are effective treatment options for biceps pathology, but outcomes of revision surgery are not known. This study examines the clinical outcomes of patients who have undergone a revision biceps tenodesis.

Materials and Methods:

A retrospective review of all patients since 2004 (N = 21) who had undergone a revision biceps tenodesis with greater than 6-month follow-up was completed. A follow-up survey was carried out, and the visual analog scale (VAS), Single Assessment Numeric Evaluation (SANE), Simple Shoulder Test (SST), American Shoulder and Elbow Surgeons (ASES), and University of California – Los Angeles (UCLA) scores were obtained, along with SF-12 Mental (MCS-12) and Physical Component Summaries (PCS-12).

Results:

Indications for revision surgery were continued pain (14) and ruptured biceps (7). Complete follow-up examinations were performed in 15 of 21 patients (71.4%). Average follow-up was 33.4 ± 23.5 months. The mean postoperative scores were 1.9 out of 10, VAS; 79 out of 100, SANE; 10.2 out of 12, SST; 83 out of 100, ASES; 29 out of 35, UCLA; 44, PCS- 12; and 47.1, MCS- 12. Five patients were considered failures with a UCLA score below 27. Seventeen of twenty-one patient underwent concomitant procedures. Complete preoperative and postoperative data were collected for 14 patients. All scores demonstrated highly significant improvement from preoperative levels (P < 0.005), except for the MCS-12. There was no statistically significant difference in the outcomes of revision due to rupture and revision due to persistent pain.

Conclusions:

The results suggest that revision subpectoral biceps tenodesis provides significant pain relief and improvement in functional outcomes at a mean follow-up of 33.4 months.

Level of Evidence:

Case Series, Level 4.

Treatment of locked chronic posterior dislocation of the shoulder by reconstruction of the defect in the humeral head with an allograft

The treatment of a chronic posterior dislocation of the shoulder is often determined by the size of the associated impression fracture of the humeral head. Our hypothesis was that patients with a chronic unreduced posterior dislocation of the shoulder and a defect in the humeral head involving between 25% to 50% of the articular surface, would do better if reconstructed with an allograft from the femoral head rather than treated by a non-anatomical reconstruction. We reviewed ten men and three women with a mean age of 42 years (36 to 51) at a mean follow-up of 54 months (41 to 64) who had this procedure. At follow-up, nine had no pain or restriction of activities of daily living. Their mean Constant-Murley shoulder score was 86.8 (43 to 98). No patient had symptoms of instability of the shoulder. Reconstruction of the defect in the humeral head with an allograft provides good pain relief, stability and function for patients with a locked, chronic posterior dislocation where the defect involves between 25% and 50% of the circumference of the articular surface.

Superoxide Dismutase Targets NO from GSNO to Cysβ93 of Oxyhemoglobin in Concentrated but Not Dilute Solutions of the Protein

The role of hemoglobin (Hb) in transmitting the vasodilatory property of NO throughout the vascular system is of much current interest. NO exchange between Hb and low-molecular-weight nitrosothiols such as S-nitrosoglutathione (GSNO) has been speculated and reported in vitro. Previously, we reported that NO delivery from GSNO to Cysbeta93 of human oxyHb is prevented in the presence of the Cu chelators, neocuproine, and DTPA.(1) In the present work, 5 mM solutions of commercial human Hb were found by ICP-MS to contain approximately 20 microM Cu and Zn, suggesting the presence of Cu,Zn-superoxide dismutase (CuZnSOD), which was confirmed by Western blotting. SOD activity measurements were consistent with the presence of approximately 20 microM CuZnSOD monomer in 5 mM Hb solutions, which is the physiological concentrations of these proteins in the red blood cell. Incubation of 3.75 mM oxyHb (15 mM heme; 7.5 mM Cysbeta93) with 3.75 or 7.5 mM GSNO gave rise to 50% or 100% S-nitrosation, respectively, of Cysbeta93 as monitored by FTIR nu(SH) absorption, whereas excess GSNO over Cysbeta93 converted oxyHb to metHb due to the reaction, oxyHb + NO<==>metHb + NO(3)(-). Removal of CuZnSOD by anion-exchange chromatography yielded an oxyHb sample that was unreactive toward GSNO, and replacement with bovine CuZnSOD restored reactivity. Addition of 1 microM GSNO (Cysbeta93/GSNO = 1) to solutions diluted 10(4)-fold from physiological concentrations of oxyHb and CuZnSOD resulted largely in metHb formation. Thus, this work reports the following key findings: CuZnSOD is an efficient catalyst of NO transfer between GSNO and Cysbeta93 of oxyHb; metHb is not detected in oxyHb/GSNO incubates containing close to the physiological concentration (5 mM) of Hb and CuZnSOD when the Cysbeta93/GSNO molar ratio is 0.5 to 1.0, but metHb is detected when the total Hb concentration is low micromolar. These results suggest that erythrocyte CuZnSOD may play a critical role in preserving the biological activity of NO by targeting it from GSNO to Cysbeta93 of oxyHb rather than to its oxyheme.

Heme nitrosylation of deoxyhemoglobin by s-nitrosoglutathione requires copper

NO reactions with hemoglobin (Hb) likely play a role in blood pressure regulation. For example, NO exchange between Hb and S-nitrosoglutathione (GSNO) has been reported in vitro. Here we examine the reaction between GSNO and deoxyHb (HbFe(II)) in the presence of both Cu(I) (2,9-dimethyl-1, 10-phenanthroline (neocuproine)) and Cu(II) (diethylenetriamine-N,N,N',N",N"-pentaacetic acid) chelators using a copper-depleted Hb solution. Spectroscopic analysis of deoxyHb (HbFe(II))/GSNO incubates shows prompt formation (<5 min) of approximately 100% heme-nitrosylated Hb (HbFe(II)NO) in the absence of chelators, 46% in the presence of diethylenetriamine-N,N,N',N",N"-pentaacetic acid, and 25% in the presence of neocuproine. Negligible (<2%) HbFe(II)NO was detected when neocuproine was added to copper-depleted HbFe(II)/GSNO incubates. Thus, HbFe(II)NO formation via a mechanism involving free NO generated by Cu(I) catalysis of GSNO breakdown is proposed. GSH is a source of reducing equivalents because extensive GSSG was detected in HbFe(II)/GSNO incubates in the absence of metal chelators. No S-nitrosation of HbFe(II) was detected under any conditions. In contrast, the NO released from GSNO is directed to Cysbeta(93) of oxyHb in the absence of chelators, but only metHb formation is observed in the presence of chelators. Our findings reveal that the reactions of GSNO and Hb are controlled by copper and that metal chelators do not fully inhibit NO release from GSNO in Hb-containing solutions.

Arthroscopic shoulder stabilization with suture anchors: technique, technology, and pitfalls

Arthroscopic treatment of anterior shoulder instability has evolved significantly during the past decade. Currently, most techniques include the use of suture and suture anchors. A successful outcome is highly dependent on accurate patient selection. Preoperative evaluation, examination with the patient under anesthesia, and defining the pathoanatomy by a thorough arthroscopic examination determine the most effective treatment strategy. Technical skills include the surgeon's ability to accomplish anchor placement, suture passage, and arthroscopic knot tying. Various instruments and techniques are available to facilitate arthroscopic reconstruction. In properly selected patients and with good surgical technique, outcomes should approximate or exceed traditional open stabilization techniques.

Arthroscopic Bankart repair with the Suretac device for traumatic anterior shoulder instability in athletes

Arthroscopic treatment of anterior shoulder instability in the athlete has evolved tremendously over the past decade. Currently, most techniques include the use of suture and suture anchors. However, the variety of arthroscopic instruments and techniques that are available shows the complexity of intra-articular tissue fixation, which includes anchor placement, suture passing, and knot tying. Stabilization using the Suretac device (Acufex Microsurgical, Mansfield, MA) simplifies tissue fixation by eliminating the need for arthroscopic suture passing and intra-articular knot tying. However, a successful outcome is highly dependent on accurate patient selection. Preoperative evaluation, examination under anesthesia, and the pathoanatomy defined by a thorough arthroscopic examination suggest the most effective treatment strategy. The ideal candidate for shoulder stabilization using the Suretac device is an athlete with a relatively pure traumatic anterior instability pattern with detachment pathology (e.g., Bankart lesion) and minimal capsular deformation.

Suprascapular neuropathy

Suprascapular neuropathy is an uncommon cause of shoulder pain and weakness and therefore may be overlooked as an etiologic factor. The suprascapular nerve is vulnerable to compression at the suprascapular notch as well as at the spinoglenoid notch. Other causes of suprascapular neuropathy include traction injury at the level of the transverse scapular ligament or the spinoglenoid ligament and direct trauma to the nerve. Sports involving overhead motion, such as tennis, swimming, and weight lifting, may result in traction injury to the suprascapular nerve, leading to dysfunction. The diagnosis of suprascapular neuropathy is based on clinical findings and abnormal electrodiagnostic test results, after the exclusion of other causes of shoulder pain and weakness. Magnetic resonance imaging may provide an anatomic demonstration of nerve entrapment and muscle atrophy. With this modality, ganglion cysts are recognized with increasing frequency as a source of external compression of the suprascapular nerve. Without evidence of a discrete lesion compressing the nerve, nonoperative treatment should include physical therapy and avoidance of precipitating activities. When nonoperative treatment fails to alleviate symptoms or when a discrete lesion such as a ganglion cyst is present, surgical decompression is warranted. Decompression gives reliable pain relief, but recovery of shoulder function and restoration of atrophied muscle tissue may be incomplete.

Repair of full thickness rotator cuff tears. Gender, age, and other factors affecting outcome

Seventy-two full thickness rotator cuff tears (72 patients) were treated with an open rotator cuff repair between 1986 and 1993. The average postoperative followup was 54 months (range, 24-102 months; standard deviation, 22 months). Fifty-three (74%) patients had no pain, 16 (22%) patients had slight pain without restriction of activities, and three (4%) patients had moderate pain with activity compromise. Women with an associated biceps tendon rupture tended to have worse results. Women had a negative, statistically significant relationship between age and shoulder scoring scales, but age at the time of surgery was not related to any outcome variables for men. A rotator cuff tear greater than or equal to 5 cm2 as determined at the time of surgery was associated with a poorer outcome. The average University of California at Los Angeles score was 32 points (range, 7-35 points; standard deviation, 5 points). The average Constant-Murley score was 78 of 100 points (range, 12-95 points; standard deviation, 15 points). A yes response was given for an average of 10 of 12 questions on the Simple Shoulder Test (range, 0-12 questions; standard deviation, 3 questions). More than 4 years after open rotator cuff repair, patients had a 94% patient satisfaction rate with lasting relief of pain and improved function.

Glenohumeral motion after complete capsular release

The range of glenohumeral motion is primarily limited by the joint capsule. If the capsule is contracted, greater restriction in glenohumeral motion is exhibited. Release of a tight capsule has been an effective means of managing refractory stiffness of the glenohumeral joint. The effect of a complete capsular release on glenohumeral kinematics has not been previously studied in a cadaver model. Elevation, rotation, and translation of eight cadaveric glenohumeral preparations were studied before and after complete capsular release. As the intact joint was positioned near the limits of motion, glenohumeral torque rose rapidly with relatively small concomitant increases in elevation and rotational angles. Notable torque, due to tension in the capsule or cuff, ensued only after glenohumeral elevation reached approximately 80% of maximal range. After complete capsular release, maximal elevation increased on average 15%, yet retained definitive endpoints due to residual tension in the rotator cuff. Axial humeral rotation with an intact capsule decreased as maximum elevation approached, especially at elevation angles greater than 60 degrees. Maximum internal rotation was less than external, for all planes except +90 degrees. After complete capsular release, the greatest net gains for external rotation tended to be in the posterior scapular planes, whereas gains for internal rotation tended to be in the anterior scapular planes. Maximal translation in an intact vented capsule was 21 mm, 14 mm, and 15 mm in the anterior, posterior, and inferior directions, respectively. After complete capsular release, translation increased in all positions with maximal anterior, posterior, and inferior translations of 28 mm, 25 mm, and 28 mm, respectively. In general, relative gains in translation were greater in planes posterior to the scapula and at extremes of the range of motion. Although large glenohumeral translations were measured, no preparation could be dislocated before or after complete capsular release. Complete capsular release significantly increased glenohumeral range of motion and translation. The intact rotator cuff myotendinous units serves to limit the range of motion and translation after all capsuloligamentous attachments are rendered incompetent by complete capsular release.

Arthroscopic treatment of infrapatellar tendonitis

Infrapatellar tendonitis is a chronic overload lesion in the patellar ligament at the attachment to the lower pole of the patella. This lesion is found primarily in athletes who participate in jumping sports. Magnetic resonance imaging or ultrasound can show the extent of tendon pathology. Patellar tendonitis is treated with modification of activities, medications, and therapy. When conservative measures fail, operative debridement has been recommended. Previous reports have described a technique of open debridement of the patellar tendon, followed by an extended period of rehabilitation before returning to sports. Two athletes with persistent infrapatellar tendonitis were treated with an arthroscopic debridement. Both athletes returned to full activities without restrictions within 8 weeks of surgery. Arthroscopic treatment of infrapatellar tendonitis has not been previously described. This technical note describes the technique and two case reports of the arthroscopic treatment of infrapatellar tendonitis.

Understanding shoulder arthroplasty

This article discusses the vital role of the professional nurse when caring for patients who have shoulder replacement surgery. The indications for surgery, recent advances in the surgical procedure, postoperative management, and potential complications are reviewed.

The humeroscapular motion interface

Motion between the humerus and scapula commonly is described as glenohumeral motion. However, humeroscapular motion occurs at two distinct sites. In addition to the motion at the diarthrodial glenohumeral joint, movement occurs between the proximal humerus and related structures and the surrounding sleeve of structures, including the acromion, deltoid, coracoid, coracoacromial ligament, and the muscles attached to the coracoid. This site of nonarticular shoulder motion is defined as the humeroscapular motion interface. Nonarticular humeroscapular motion can be documented and measured using standard magnetic resonance imaging techniques. The maximum average interfacial motion using axial images was 29.1 mm, which occurred at the level of the maximum diameter of the humeral head. Interfacial motion varied depending on the site measured. If pathologic conditions such as adhesions secondary to trauma or surgery interfere with or obliterate this space at sites of significant sliding motion, overall shoulder motion will be limited. Successful treatment of shoulder stiffness related to humeroscapular restraints is likely to require restoration of the normal sliding motion at the humeroscapular motion interface, in addition to resolving restraints affecting the glenohumeral joint motion.

Scoring systems for shoulder conditions

We evaluated the comparability of four commonly used shoulder scoring systems in the United States. Fifty-two patients had 53 shoulder stabilization procedures. Surgical procedures included 34 open Bankart-type repairs, 15 capsular shifts, and 4 arthroscopic stabilizations. Results were assessed using the following scales: 1) Rowe, 2) modified-Rowe, 3) University of California at Los Angeles, and 4) the pre-1994 American Shoulder and Elbow Surgeons scale. No consensus has been reached on the relative value of these systems. We observed significant variations using these systems. A majority of our patients (85%) had excellent results when the University of California at Los Angeles scoring system was used. However, only 38% of the patients had excellent results when the modified-Rowe scale was used. Overall, good or excellent results were observed in 89% to 95% of the patients using these four scoring systems. The University of California at Los Angeles score correlated poorly with the other systems. Interrater reliability between the four systems was poor. Generalized results of an investigation can be biased based on the selection of a scoring system. The lack of a widely accepted scoring system for the shoulder limits comparison of management for shoulder conditions. Thus, a widely accepted shoulder scoring system is needed.

Total shoulder arthoplasty: pearls and pitfalls in surgical technique

Total should arthroplasty is recommended for the treatment of shoulder arthritis that causes severe pain and loss of function. Successful shoulder arthroplasty is a technically demanding procedure because of lack of intrinsic stability of the glenohumeral joint. The tension of the rotator cuff and glenohumeral capsule must be balanced for mobility and stability. Attention to important anatomic landmarks and glenohumeral relationships ("pearls") minimizes the risk of complications ("pitfalls").

Surgical resection of the distal clavicle

Distal clavicle resection is frequently performed for persistent acromioclavicular pain. However, patient outcome after this procedure has not been well described. The results of subjective and objective retrospective analysis of 23 open distal clavicle resections in 21 patients are reported. Patients were evaluated with a questionnaire, roentgenographs, physical examination, and isokinetic muscle strength testing at an average of 30 months after surgery. Eighteen of 23 shoulders had good or excellent postoperative ratings. All patients had normal motion. No significant weakness of the operated shoulder was seen on objective muscle testing when compared with the unoperated shoulder. The average preoperative Hospital for Special Surgery score was 34, and the average postoperative score was 84. Age and hand dominance were unrelated to postoperative outcomes. Less predictable results were obtained in patients with workmen's compensation and in those patients involved in litigation. Open distal clavicle resection yields good to excellent results in properly selected patients and does not create significant subjective or objective weakness.

Total shoulder arthroplasty: Some considerations related to glenoid surface contact

The area of prosthetic surface contact is an important surgeon-controlled variable in total shoulder arthroplasty and is related to the geometry of the glenoid and humeral articular surfaces and their relative positions. This study explores some of the factors that affect joint surface contact area. We measured the humeral and the glenoid articular surface angles in the superior-inferior and anteroposterior planes for two prosthesis systems representative of those in common clinical use. On the basis of these data we determined the range of glenohumeral positions providing full glenoid surface contact, a condition in which all of the articular surface of the glenoid component is in contact with the articular surface of the humeral component. We found a wide variability in the range of glenohumeral positions providing full glenoid contact with different prosthetic combinations. Some combinations do not even offer full glenoid surface contact with the joint in the centered position, for example, when the center of the humeral head articular surface is opposed to the center of the glenoid articular surface. The maximal range of glenohumeral positions providing full glenoid surface contact was 117° for a combination with a small radius of head curvature and a large articular surface angle. The relative positions of the humeral and glenoid articular surfaces also have a major influence on the joint contact area. Some combinations offer full glenoid surface contact only in a position of humeral abduction with respect to the scapula. Loss of full glenoid surface contact between the glenoid and humerus may allow for unwanted translations of the humeral head on the glenoid in the direction where contact is lacking. Furthermore, in positions where full surface contact is lacking, humeral bone or soft tissue may make unwanted contact with the glenoid. These results suggest that the design of the humeral articular surface and the surgical procedure should maximize full glenoid surface contact in functionally important positions.

Prospective reimbursement and the diffusion of new technologies in hospitals

This paper presents new evidence on the effects of prospective hospital reimbursement on the diffusion of new medical technologies in American hospitals. The probability, speed, and extent of adoption of five specific new technologies in six states, three with prospective reimbursement and three without, are examined using the results of a hospital survey conducted by the American Hospital Association for this study in 1980. The analysis demonstrates the influence of prospective reimbursement on the diffusion of new technologies. It is clear as well that these effects depend upon the specific attributes of the prospective reimbursement program and the characteristics of the technologies themselves.