Are displaced distal clavicle fractures associated with inferior clinical outcomes following nonoperative management? A systematic review.

BACKGROUND: Management of displaced distal clavicle fractures remains a topic of discussion because of notoriously high nonunion rates, but there is little documented in the literature as to what effect this may have on patient-reported function. The aim of this systematic review was to look at nonoperative management following displaced distal clavicle fractures to determine union rates, complications, and patient-reported outcome measures. METHODS: A review of the online databases MEDLINE and Embase was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Clinical studies that included a cohort of nonoperatively managed displaced distal clavicle fractures and reported on union rate, complications, and patient-reported functional scores were included. RESULTS: Eleven studies were eligible for inclusion (2 randomized controlled trials, 1 prospective noncomparative cohort study, 5 retrospective comparative cohort studies, and 3 case series) with a total of 779 patients included in this review. Average union rate was 63.2% (22.2%-94.4%) in nonoperatively managed patients, compared with 96.3% (87.9%-100%) in operatively managed patients. The Constant-Murley score and Disabilities of the Arm, Shoulder, and Hand questionnaire were the most frequently used outcome measure tools. No study demonstrated any significant difference in any outcome measure when comparing nonoperative with operative treatment. Complication rate (including nonunion) in nonoperatively managed patients was 45.1%, with 11.1% requiring delayed surgery. Average complication rate in the operatively managed groups was 41.2%, with 40.1% requiring a second operation. CONCLUSION: Nonoperative management of displaced distal clavicle fractures results in higher nonunion rates, but shoulder function remains excellent, and risk of complications and delayed surgery are low. Decision making must take into account patient factors and expectations to provide high-quality, individualized care.

Supraspinatus muscle atrophy in relation to aging with or without shoulder pathology: A radiographic study.

Introduction: Supraspinatus muscle atrophy is commonly associated with shoulder disease, but the effect of ageing on atrophy is not well understood. It was the aim of this study to investigate this effect using MRI scans in older patients. Methods and materials: A retrospective review of MRI scans in patients aged >70 years was performed between Jan 2016-Dec 2018.Both normal and abnormal scans were included in the analysis which included quantifying muscle atrophy of the supraspinatus using Thomazeu's occupation ratio. Results: There were 39 normal shoulder MRI scans with a mean age of 75 years (range: 70-88) and 163 abnormal scans with a mean age of 77 years (range: 70-93). The mean supraspinatus occupation ratio for normal MRI scans was 0.57 (range: 0.33-0.86) and abnormal scans 0.35 (range: 0.17-0.90). Occupation ratio was maintained with advancing until the age of 85 years before undergoing a significant declin following this. Conclusion: This study has shown that the occupation ratio is significantly reduced with shoulder disease, but normal shoulders do not undergo significant atrophy of supraspinatus tendon with increasing age. An occupation ratio of <0.32 is unlikely to occur in normal shoulders and this awareness may be useful when planning shoulder surgery, specifically shoulder arthroplasty.

Mid- to long-term outcomes of a cemented, all-polyethylene pegged glenoid component in anatomic total shoulder arthroplasty.

BACKGROUND: The primary aim of this study was to evaluate mid- to long-term survival of an all-polyethylene pegged glenoid component used in anatomic total shoulder arthroplasty (TSA). The secondary aim was to review clinical and radiologic outcomes. METHODS: A retrospective analysis of a prospectively collected local arthroplasty register of consecutive patients undergoing TSA with an all-polyethylene pegged glenoid between January 2009 and December 2018 was undertaken. In total, 108 TSAs using this implant were performed in our unit in 98 patients (18 men and 80 women), with 10 patients undergoing bilateral TSA. The mean age at the time of the operation was 71.3 years (range, 44-87 years). The mean follow-up period was 5.1 years (range, 2-10.6 years). In addition to survival analysis, clinical evaluation included the postoperative Oxford Shoulder Score, Constant score, and visual analog scale (VAS) pain score, as well as range-of-motion assessment. Radiologic outcomes included an assessment of radiolucency based on the Lazarus grade. RESULTS: Kaplan-Meier survival analysis revealed a 6-year survival estimate of 94.1% for all-cause revision. Revision was required in 6 patients: 4 for cuff failure and 2 for instability. At follow-up, the mean Oxford Shoulder Score was 38.2 (standard deviation [SD], 12.3); mean Constant score, 59.3 (SD, 17.0); and mean VAS pain score, 1.8 (SD, 2.5). Mean forward elevation at final follow-up was 111° (SD, 26.6°); mean abduction, 102° (SD, 34.0°). Clinical outcomes were maintained at long-term follow-up (>8 years), with the exception of the VAS pain score, which increased by 2.1 points (P = .034). Radiologic assessment revealed that 28 patients had radiolucency consistent with Lazarus grade ≥ 3 with clinical outcomes not being affected. CONCLUSIONS: Mid- to long-term follow-up indicates a low revision rate and good clinical survivorship for cemented, all-polyethylene glenoid components. No patients, so far, have undergone revision for glenoid loosening, but radiographic follow-up has shown that 36% of these implants have signs of radiolucency. Further follow-up is required to determine longer-term survivorship.

Radiological and Long-Term Functional Outcomes of Displaced Distal Clavicle Fractures.

OBJECTIVES: To investigate radiological and long-term functional outcomes in modified Neer 2a, 2b, and 5 distal clavicle fractures. DESIGN: Retrospective cohort study. SETTING: A single university teaching hospital. PATIENTS/PARTICIPANTS: One hundred fifteen patients sustaining displaced distal clavicle fractures between January 01, 2010 and December 12, 2017. INTERVENTION: Operative versus nonoperative management. MAIN OUTCOME MEASUREMENTS: Radiographs were reviewed for fracture management and union. A customised questionnaire consisting of QuickDASH (Disabilities of the Arm, Shoulder and Hand), work, sports/performing arts, global satisfaction, and complication modules was used to determine functional outcome. RESULTS: One hundred fifteen patients were included [mean age of 49 (18-89) years]. Thirty-three (29%) underwent early fixation (<6 weeks from injury) and were younger (37 vs. 53 years, P < 0.0001). Radiographs were available for 96 patients. Nonunion rate was 55% (53/96), and majority had undergone initial nonoperative management (49 vs. 4, P < 0.00001). Eleven patients with symptomatic nonunion were deemed appropriate for delayed fixation with all cases uniting. Of the operatively managed patients, 27% (12/44) underwent metalwork removal. There were no differences in functional outcome between operative versus nonoperative and union versus nonunion patient groups at a mean follow-up of 79 months ( P > 0.05). CONCLUSION: Functional outcome and patient satisfaction at long-term follow-up were similar regardless of operative fixation or radiological union. Nonunion in displaced distal clavicle fractures seemed to cause minimal functional deficit in most elderly sedentary individuals, or the outcome measures were not sensitive enough to capture these differences. An individualized approach should be adopted, with less active, comorbid, and elderly patients counseled regarding the minimal functional improvement of surgery and risk of reoperation. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

The management of displaced humeral shaft fractures - A survey of UK shoulder and elbow surgeons.

Introduction: Indications for surgical management of displaced humeral shaft fractures are not clearly established, leading to variations in practice. The aim of this study was to determine the scale of these variations in the UK practice to help design a future national trial. Methods: An online survey was sent to all surgeon members of British Elbow and Shoulder Society to help define humeral shaft fractures, fracture displacement as well as indications for operative and non-operative management. Patient and injury related factors considered important when managing humeral shaft fractures were investigated. Results: The survey achieved a response rate of 32% (104/327). There was a lack of consensus on definitions for humeral shaft fractures and fracture displacement. A functional brace was the most common form of non-operative treatment (63%). Majority immobilise humeral shaft fractures for 4-8 weeks or until callus are visible (62%) with a similar number considering operative treatment if adequate signs of healing are not present at around 12-16 weeks. Around half of our respondents exclusively use plates with variations in preference of approach and a minority (2%) exclusively use intra-medullary nails. Conclusion: The significant variation in management of displaced humeral shaft fractures in the UK suggests a clear need to evaluate clinical and cost effectiveness through a multi-centre randomised trial.

Interposition GraftJacket allografts for irreparable rotator cuff tears.

AIMS: Long-term outcomes following the use of human dermal allografts in the treatment of symptomatic irreparable rotator cuff tears are not known. The aim of this study was to evaluate these outcomes, and to investigate whether this would be a good form of treatment in young patients in whom a reverse shoulder arthroplasty should ideally be avoided. METHODS: This prospective study included 47 shoulders in 45 patients who underwent an open reconstruction of the rotator cuff using an interposition GraftJacket allograft to bridge irreparable cuff tears, between January 2007 and November 2011. The Oxford Shoulder Score (OSS), pain score, and range of motion (ROM) were recorded preoperatively and at one year and a mean of 9.1 years (7.0 to 12.5) postoperatively. RESULTS: There was significant improvement in the mean OSS from 24.7 (SD 5.4) preoperatively to 42.0 (SD 6.3) at one year, and this improvement was maintained at 9.1 years (p < 0.001), with a score of 42.8 (SD 6.8). Similar significant improvements in the pain score were seen and maintained at the final follow-up from 6.1 (SD 1.6) to 2.1 (SD 2.3) (p < 0.001). There were also significant improvements in the ROM of the shoulder, and patient satisfaction was high. CONCLUSION: The use of an interposition human dermal allograft in patients with an irreparable rotator cuff tear leads to good outcomes that are maintained at a mean of nine years postoperatively. Cite this article: Bone Joint J 2022;104-B(1):91-96.

Use of Suture Tapes Versus Conventional Sutures for Arthroscopic Rotator Cuff Repairs: A Systematic Review and Meta-analysis.

BACKGROUND: Various suture materials are available for arthroscopic rotator cuff repair. More recently, suture tapes have become popular as they are perceived to be easier to use with less soft tissue irritation. However, little is known about their biomechanical and clinical properties compared with conventional sutures in rotator cuff repairs. PURPOSE: To perform a systematic review and meta-analysis on whether suture tapes are biomechanically superior to conventional sutures in arthroscopic rotator cuff repairs and whether this translates to superior functional outcomes and a lower incidence of retears. STUDY DESIGN: Meta-analysis. METHODS: The Cochrane Controlled Register of Trials, PubMed, Medline, and Embase were used to perform a systematic review and meta-analysis using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria with the following search terms: (rotator cuff repair OR arthroscopic rotator cuff repair) AND ("tape" OR "wire" OR "cord" OR "suture"). Data pertaining to certain biomechanical properties (contact area, contact pressure, gap formation, load to failure, and stiffness), retears, and patient-reported outcome measures (PROMs) were extracted. The pooled outcome data were analyzed by random- and fixed-effects models. RESULTS: After abstract and full-text screening, 7 biomechanical and 6 clinical studies were included. All biomechanical studies were on animals, with 91 suture tapes and 91 conventional sutures compared. Suture tapes had higher contact pressure (mean difference [MD], 0.04 MPa; 95% CI, 0.01-0.08; P = .02), higher load to failure (MD, 52.62 N; 95% CI, 27.34-77.90; P < .0001), greater stiffness (MD, 4.47 N/mm; 95% CI, 0.57-8.38; P = .02), and smaller gap formation (MD, -0.30 mm; 95% CI, -0.45 to -0.15; P < .0001) compared with conventional sutures. From the clinical analysis of the 681 rotator cuff repairs treated with a suture tape (n = 380) or conventional suture (n = 301), there were no differences in retear rates between the groups (16% vs 20% suture tape and wire, respectively; P = .26) at a mean of 11.2 months. Qualitatively, there were no differences in PROMs between the groups at a mean of 36.8 months. CONCLUSION: Although biomechanically superior, suture tapes showed similar retear rates and postoperative function to conventional sutures. However, higher-quality clinical studies are required to investigate whether there are no true differences.

Floor and ceiling effects in the Oxford Shoulder Score : an analysis from the National Joint Registry.

AIMS: The main objective of this study was to examine whether the Oxford Shoulder Score (OSS) demonstrated floor or ceiling effects when used to measure outcomes following shoulder arthroplasty in a large national cohort. Secondary objectives were to assess its pain and function subscales, and to identify independent predictors for patients achieving a postoperative ceiling score following shoulder arthroplasty. METHODS: Secondary database analysis of the National Joint Registry (NJR), which included 48,270 patients undergoing shoulder arthroplasty, was conducted. The primary outcome measure was the OSS. Secondary outcome measures were the OSS-Function Component Subscale and OSS-Pain Component Subscale. Floor and ceiling effects were considered to be present if > 15% of patients scored either the lowest or highest possible score. Logistic regression analysis was used to identify independent predictors for scoring the highest possible OSS score postoperatively. RESULTS: Preoperatively, 1% of patients achieved the lowest possible OSS score (0) and 0.4% of patients achieved the highest possible score (48). Postoperatively, < 1% of patients achieved the lowest score at all timepoints, but the percentage achieving the highest score at six months was 8.3%, at three years 16.9%, and at five years 17%. Male patients, those aged between 60 and 89 years, and those undergoing an anatomical total shoulder arthroplasty (ATSA) were more likely to contribute to the ceiling effect seen in the OSS questionnaire. Pain and function subscales exhibited greater ceiling effects at three years and five years when compared with the overall OSS questionnaire. Logistic regression analysis showed that sex, procedure type, and preoperative OSS score were independent predictors for scoring the highest possible OSS at years. CONCLUSION: Based on NJR patient-reported outcome measures data, the OSS does not exhibit a ceiling effect at six months, but does at three years and five years, in part due to outcome scores of ATSA. Preoperative OSS, age, male sex, and ATSA are independent predictors of achieving a ceiling score. Cite this article: Bone Joint J 2021;103-B(11):1717-1724.

Treatment of massive irreparable rotator cuff tears using dermal allograft bridging reconstruction.

AIMS: Various options are available for treating massive irreparable rotator cuff tears, but all have their own limitations and no gold standard currently exists. Our aim was to report on outcomes of bridging repair with a dermal allograft for symptomatic massive irreparable rotator cuff tears where primary or partial repair was not possible. PATIENTS AND METHODS: We prospectively reviewed 22 patients who underwent an open interposition bridging repair with an allograft (GraftJacket) sutured medially to the residual rotator cuff stump and laterally to the footprint with suture anchors. Mean age at time of surgery was 59 years (range 53-66 years). The Oxford Shoulder Score, pain visual analogue scale and range of motion were compared pre-operatively and at mean follow up of 2.8 years. All patients had a postoperative MRI scan. RESULTS: There was a significant improvement in mean Oxford Shoulder Score from a pre-operative score of 14.2-34.3 points (p < 0.01) at final follow up. Pain VAS score improved from 6.6 points to 2.8 points (p < 0.05). Significant improvements in range of motion were also seen. Postoperative MRI scans showed a retear in 8 patients (36%), but the retear size was smaller and an improvement in outcomes maintained at final follow up. CONCLUSION: Open dermal allograft bridging repair for massive irreparable rotator cuff tears can lead to satisfactory outcomes and delay the need for a reverse shoulder arthroplasty.

Interposition grafting for irreparable rotator cuff tears: Systematic review and specialist practice report.

The treatment of symptomatic irreparable rotator cuff tears poses significant challenges to both patients and shoulder surgeons. Although reverse shoulder arthroplasty provides reliably good outcomes in the elderly, it is not a good option in younger patients. Various surgical techniques have been proposed for the treatment of irreparable rotator cuff tears; however, no gold standard currently exists. Interposition grafting is used when the rotator cuff cannot be fully repaired onto its footprint, and the remaining defect is bridged with either an allograft, autograft, xenograft or a synthetic graft. This review aims to present the literature on the use of various interposition grafts and techniques to treat large or massive irreparable rotator cuff tears and provide a specialist practice report.

Venous thromboembolic events in hand surgery.

The risks of venous thromboembolism (VTE) following total hip and knee arthroplasty have been widely published. Our aim was to investigate the recorded incidence of VTE events at the time of elective and trauma hand surgery. The UK National Hospital Episode Statistics (HES) data linking VTE events with hand surgery for the financial years 2010-2012 were analysed. The local VTE rates following hand surgical procedures were also analysed. Finally, a cost assessment of VTE thromboprophylaxis was performed according to the British Society for Surgery of the Hand (BSSH) guidelines. 334,211 hand surgical procedures were performed throughout England of which there were 13 DVT and 27 PE events. These events were seen in patients with pre-existing comorbidities. The annual incidence of VTE is 0.006% at most in hand surgical patients in England. The cost of implementing mechanical VTE thromboprophylaxis to all patients having hand surgery would amount to £6,336,641 over 2 years. The cost of treatment for all VTE events would amount to £20,418. VTE prophylaxis is probably not necessary in patients undergoing isolated elective or trauma hand surgical procedures.

Mortality following combined fractures of the hip and proximal humerus.

BACKGROUND: Hip fractures and proximal humerus fractures are known to be associated with increased mortality, but the impact on mortality of combining these two common injuries is not well known. AIM: To compare mortality, inpatient stay and discharge destination for patients with combined hip and proximal humerus fractures with those sustaining isolated hip fractures. METHODS: Using the United Kingdom national hip fracture database, we identified all hip fracture patients over the age of 60 admitted to a single trauma unit from 2010-2016. Patients sustaining a proximal humerus fracture in addition to their hip fracture were identified using hospital coding data. We calculated the 30-d and one-year mortality for both the hip fracture cohort and the combined hip and proximal humerus fracture cohort. Other variables recorded included age, gender and whether the proximal humerus was treated with or without an operation. RESULTS: We identified 4131 patients with hip fractures within the study period and out of those 40 had sustained both a hip and a proximal humerus fracture. Mean age in the hip fracture cohort was 80.9 years and in the combined fracture group 80.3 years. Out of the 40 patients in the combined group four were treated operatively. The 30-d mortality for our hip fracture cohort was 7.2% compared to the mortality of our combined cohort of 12.5% (P = 0.163). The one-year mortality for our hip fracture cohort was 26.4% compared to 40% for the combined fracture cohort (P = 0.038). We also found patients with combined injuries were less likely to return to their own home. CONCLUSION: The 30-d and one-year mortality is higher for those patients who have sustained a combined hip and proximal humerus fracture when compared to those with a hip fracture alone.

A systematic review of displaced paediatric distal radius fracture management: Plaster cast versus Kirschner wiring.

Displaced distal radius fractures involving the metaphysis are common childhood injuries requiring intervention. Patients frequently undergo operative treatment for these injuries. The aim of our study was to systematically review the literature comparing manipulation under anaesthesia (MUA) and Kirschner wire fixation(K wire). PRISMA guidelines were followed throughout. Medline and Cochrane databases were searched for comparative randomised controlled trials (RCTs) and cohort studies. Quality assessment was undertaken using the Jadad score, Cochrane assessment of bias tool and the Newcastle-Ottawa Scale. Data extraction was performed with customised forms. 2 RCTs and 4 cohort studies were included. There was significant variation in their methodologies, which included their inclusion criteria and threshold for remanipiulation. Re-operation rates for MUA varied from 14% to 91%. There were no recorded re-operations following K-wiring. There was a 2.2% infection rate and 4.5% rate of wire migration. There were no adverse long-term sequelae reported. All studies showed a higher re-operation rate with MUA alone. Further studies are required to identify which fracture subtypes are most susceptible to re-displacement. Current evidence suggests the use of a k-wire to stabIlise these fractures following manipulation.

Does structural integrity following rotator cuff repair affect functional outcomes and pain scores? A meta-analysis.

BACKGROUND: To assess whether the integrity of rotator cuff repairs has an impact on functional outcomes, as well as pain scores, after surgery. METHODS: Systematic review and meta-analyses performed for Level Ι, ΙΙ and ΙΙΙ studies that presented functional outcome scores and radiological assessment of integrity following rotator cuff repair. Extracted data included patient demographics, functional outcome scores [Constant Score, University of California at Los Angeles (UCLA) shoulder score, American Shoulder and Elbow Surgeons (ASES) shoulder score, visual analogue scale (VAS) Pain score], as well as assessment of repair integrity on radiological investigations. A meta-analysis was performed using weighted means and a random effects model. RESULTS: Twelve studies were included in the final analysis. Average re-tear rate for the 800 included patients was 22% at a mean follow-up of 27.5 months after surgery. Patients with intact repairs had a significantly higher Constant Score (8.61 points, p < 0.00001), UCLA shoulder score (2.96 points, p < 0.0001) and ASES shoulder score (9.49 points, p < 0.0006). Patients with intact repairs also reported lower pain VAS Pain scores by 0.62 points (p < 0.0004). CONCLUSIONS: Our results show better functional outcome and pain scores in patients with intact rotator cuffs at follow-up when compared to those that have re-torn. This difference is equivalent to the published Minimal Clinically Important Difference for the ASES but not Constant Scores. This review has also highlighted that shoulder strength in patients with intact cuff repairs is likely to be greater than in patients with a failed repair.

Reslip of a previously fixed slipped upper femoral epiphysis with an associated vitamin d deficiency.

Slipped upper femoral epiphysis (SUFE) is a relatively common adolescent hip disorder that represents a biomechanical instability of the proximal femoral growth plate. A link between vitamin D deficiency and SUFE has emerged in recent years; however, we present a unique case of a 10-year-old girl who presented with a reslip of a previously fixed SUFE with an associated vitamin D deficiency.

Mechanistic analysis of acute, Ni-induced respiratory toxicity in the rainbow trout (Oncorhynchus mykiss): an exclusively branchial phenomenon.

In moderately hard Lake Ontario water (approximately 140 mg L(-1) as CaCO3) waterborne Ni (9.7-10.7 mg Ni L(-1)) is acutely toxic to adult rainbow trout (Oncorhynchus mykiss) exclusively via branchial mechanisms. Ventilation in resting trout (evaluated using a ventilatory masking technique) was adversely affected, as ventilation rate (VR), ventilation volume (VG), opercular stroke volume (VSV) and resting oxygen consumption (MO2) were all increased, and oxygen extraction efficiency (U%) decreased over 48 h of Ni exposure. Extensive gill Ni accumulation (41-fold over control levels) during 82 h of waterborne Ni exposure resulted in marked ultrastructural damage to the respiratory epithelium of the gill, including swelling of the secondary lamellae evidenced by changes to both the lamellar region (increased secondary lamellar tissue volume (VSL/V(LR), and to the secondary lamellae themselves (increased volume of tissue lying outside the pillar system (VOPS/VSL). Additionally, decreased lamellar height and increased lamellar width indicated a reduction in lamellar surface area available for gas diffusion. The relative diffusing capacity of experimental fish was only 59% of that of control fish. Infusion of Ni into the blood, achieving a similar time course and magnitude of plasma [Ni] elevation to that during waterborne exposure, failed to elicit any signs of respiratory toxicity typically diagnostic of acute, high level waterborne Ni exposure. Infusion of Ni into the blood for 96 h resulted in only minor accumulation of Ni in the gill, suggesting that acute Ni-induced respiratory toxicity is related to accumulation of high levels of Ni in the gill from the water. Additionally, infusion of Ni into the bloodstream led to significant extrabranchial Ni accumulation only in the kidney. White muscle, heart, liver, stomach, and intestine did not significantly accumulate Ni following infusion into the bloodstream and trapped plasma analysis revealed that, with the exception of the kidney, a substantial portion of Ni accumulated in tissues following infusion could be accounted for by extracellular (blood-bound) Ni.

The physiological consequences of exposure to chronic, sublethal waterborne nickel in rainbow trout (Oncorhynchus mykiss): exercise vs resting physiology.

In rainbow trout (Oncorhynchus mykiss), following chronic (42 day) exposure to both 384 microg Ni l(-1) and 2034 microg Ni l(-1), Ni accumulation was greatest in the gill, kidney and plasma, with the plasma as the main sink for Ni. Indeed, trapped plasma analysis revealed that extensive loading of Ni in the plasma accounted for substantial percentages of accumulated Ni in several tissues including the liver and heart. Accumulated Ni in the gill and kidney was less dependent on plasma Ni concentration, suggesting a more intracellular accumulation of Ni in these tissues. We present evidence for a clear, persistent cost of acclimation to chronic, sublethal Ni exposure. Chronic (40-99 day) exposure to sublethal waterborne Ni (243-394 microg Ni l(-1); approximately 1% of the 96 h LC(50)) impaired the exercise physiology, but not the resting physiology, of rainbow trout. Ni acted as a limiting stressor, decreasing maximal rates of oxygen consumption (MO2,max) during strenuous exercise in trout exposed for 34 days to sublethal Ni. This drop in high-performance gas exchange was attributed mainly to a reduction in relative branchial diffusing capacity (D(rel)) caused by thickening of secondary lamellae. Morphometric analysis of the gills of chronically exposed fish revealed overall swelling of secondary lamellae, as well as hypertrophic respiratory epithelia within secondary lamellae. Additionally, contraction of the lamellar blood pillar system and narrowing of interlamellar water channels occurred, possibly contributing to decreased high-performance gas exchange. Decreased aerobic capacity persisted in fish previously exposed to nickel despite a clean-water exposure period of 38 days and an almost complete depuration of gill Ni, suggesting that extrabranchial mechanisms of chronic Ni toxicity may also be important. Chronic impairment of such a dynamically active and critical organ as the gill may depress the overall fitness of a fish by impairing predator avoidance, prey capture and migration success with obvious environmental implications.